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Background Methicillin-resistant Staphylococcus haemolyticus (MRSH) is an important pathogenic agent of bovine mastitis. Among the prominent clone lineages in dairy cows are MRSH sequence types ST3 and ST42. Little information is available on the complete characterization of SCC mec elements in MRSH. Objective In this study, two clinical isolates of MRSH ST3 and ST42 from bovine mastitis milk were selected, and their nontypable SCC mec structures were compared. Methods Two MRSH strains, MRSH-ST3 strain M62.3 and MRSH-ST42 strain M81.1, were identified from bovine mastitis milk in Thailand in 2022. Minimum inhibitory concentration was used to screen for antimicrobial resistance susceptibility. Oxford Nanopore Technologies and Illumina sequencing were performed in combination to complete the genome. Their gene organization and structure of SCC mec types were analysed and compared with the whole sequences of other strains in the same sequence types. Results Both MRSH-ST3 strain M62.3 and MRSH-ST42 strain M81.1 possessed the class C1 mec complex but lacked the ccr gene complex. Notably, MRSH-ST42 strain M81.1 contained a novel variant of C1 mec complex, which consisted of IS 431 - mecA -IS Sha1 - paaZ - upgQ -IS 431 , with IS 431 organized in the same orientation. Apart from class C1 mec and the heavy metal-resistant cluster, the gene composition and order of the SCC mec element varied. In ST3, variations in the SCC mec type, gene content and organization were observed. Conclusions The distinct evolution of the MRSH lineage was indicated by the various SCC mec elements. The insertion of IS Sha1 resulted in a unique variant of class C1 mec complex that demonstrated the important role of the insertion sequence in SCC mec diversification. [ABSTRACT FROM AUTHOR]

Background: The Staphylococcus haemolyticus and Staphylococcus warneri are coagulase-negative staphylococci (CoNS) as part of human skin’s natural flora. In recent years, CoNS has increased its visibility as opportunistic pathogens acquired in hospital patients. This study aims to isolate S. haemolyticus and S. warneri strains from patients with bloodstream infections and to analyze the antimicrobial profile of these bacteria by molecular detection of the mecA gene. Materials and Methods: Four hundred and twenty-three clinical blood samples were collected from patients admitted to general three hospitals in Hilla city, Iraq, during the period from September 2021 to July 2022. Blood samples were inoculated immediately into blood bottles containing 70 ml of Brain-Heart Infusion Broth. All isolates were identified by morphology, biochemical tests, and VITEK 2 automated system (bioMerieux, France). The Congo red agar plate test was used to detect biofilm production. The mecA gene was detected by conventional polymerase chain reaction. Results: S. haemolyticus (nine isolates) and S. warneri (six isolates) were detected out of 423 clinical blood samples. Molecular detection of the mecA gene was detected in all 15 isolates. As well 11 (73.3%) isolates were β-lactam resistant and biofilm production. The results of oxacillin-resistance minimum inhibitory concentration (MIC) (≥4 mg/ml) showed that 11 (73.3%) of the 15 isolates were oxacillin and methicillin-resistant CoNS (MR-CoNS). Susceptibility to various isolates (MICs µg/ml) using VITEK 2 system showed erythromycin (≥8 µg/ml), rifampin (≥4 µg/ml), clindamycin (≥4 µg/ml), and trimethoprim-sulfamethoxazole (≥4 µg/ml) resistance were (80%), (13.3%), (20%), and (53.3%), respectively. All isolates were (100%) sensitive to linezolid (≥8 µg/ml) and teicoplanin (≥32 µg/ml). Conclusions: The S. haemolyticus and S. warneri are serious infections associated with bacteremia and septicemia infections. Linezolid, teicoplanin, and rifampin are the drug of choice for the treatment of infections caused by MR-CoNS isolates. A high rate of the mecA gene and biofilm production is present in these bacteria.

In this case study, a 57-year-old diabetic patient was admitted to the intensive care unit (ICU) in a general hospital in Southwest Saudia Arabia following a road traffic accident (RTA). He subsequently developed a Central Line Associated Blood Stream Infection (CLABSI) with Staphylococcus haemolyticus (S. haemolyticus). Despite his fever and elevated inflammatory markers, the organism was initially dismissed as a contaminant, leading to delayed diagnosis and inadequate treatment with different antibiotics. Empirical antibiotic therapy was ineffective, prompting a change to Vancomycin following organism identification and a full susceptibility report. Communication gaps between the laboratory and clinicians, combined with the lack of rapid organism identification tools, contributed to the delay in appropriate therapy. The active surveillance of the infection control department facilitated the identification of recurring infections, leading to timely intervention and a positive outcome for the patient. This case underscores the importance of prompt and accurate organism identification, effective communication between laboratory staff and clinicians, and the proactive role of infection control doctors in detecting and managing healthcare-associated infections to ensure optimal patient care. [ABSTRACT FROM AUTHOR]

Zhao Liu,1,* Ling Wang,2,* Jiabing Sun,1,* Qinghuan Zhang,3 Yue Peng,1 Susu Tang,1 Limei Zhang,4 Xiaobin Li,4,5 Zhijian Yu,1 Tao Zhang6 1Department of Otolaryngology, Zhuhai Hospital Affiliated with Jinan University (Zhuhai People’s Hospital), Zhuhai, People’s Republic of China; 2Department of Obstetrics, Zhuhai Hospital Affiliated with Jinan University (Zhuhai People’s Hospital), Zhuhai, 519000, People’s Republic of China; 3Department of Clinical Laboratory, Zhuhai Hospital Affiliated with Jinan University (Zhuhai People’s Hospital), Zhuhai, 519000, People’s Republic of China; 4Guangdong Provincial Key Laboratory of Tumor Interventional Diagnosis and Treatment, Zhuhai Hospital Affiliated with Jinan University (Zhuhai People’s Hospital), Zhuhai, People’s Republic of China; 5Zhuhai Precision Medical Center, Zhuhai Hospital Affiliated with Jinan University (Zhuhai People’s Hospital), Zhuhai, People’s Republic of China; 6Department of Otolaryngology, The First Affiliated Hospital of Jinan University, Guangzhou, People’s Republic of China*These authors contributed equally to this workCorrespondence: Tao Zhang; Zhijian Yu, Email 18045681156@163.com; yzjent@163.comObjective: Staphylococcus haemolyticus can cause a series of infections including otitis media (OM), and the oxacillin-resistant S. haemolyticus has become a serious health concern. This study aimed to investigate the genomic characteristics of two strains of oxacillin-resistant and mecA-positive S. haemolyticus isolated from the samples of ear swabs from patients with OM and explore their acquired antibiotic resistance genes (ARGs) and the mobile genetic elements (MGEs).Methods: Two oxacillin-resistant S. haemolyticus strains, isolated from ear swab samples of patients with OM, underwent antimicrobial susceptibility evaluation, followed by whole-genome sequencing. The acquired ARGs and the MGEs carried by the ARGs, harbored by the genomes of two strains of S. haemolyticus were identified.Results: The two strains of oxacillin-resistant S. haemolyticus (strain SH1275 and strain SH9361) both carried the genetic contexts of mecA with high similarity with the SCCmec type V(5C2& 5) subtype c. Surprisingly, the chromosomal aminoglycoside resistance gene aac(6’)-aph(2”) harbored by S. haemolyticus strain SH936 was flanked by two copies of IS 256, forming the IS 256-element (IS 256-GNAT-[aac(6’)-aph(2”)]-IS 256), which was widely present in strains of both Staphylococcus and Enterococcus genus. Furthermore, the two strains of oxacillin-resistant and MDR S. haemolyticus were found to harbor antimicrobial resistance plasmids, including one 26.9-kb plasmid (pSH1275-2) containing msr(A)–mph(C)) and qacA, one mobilizable plasmid pSH1275-3 harboring vga(A)LC, one plasmid (pSH9361-1) carrying erm(C), and one plasmid (pSH9361-2) carrying qacJ.Conclusion: The systematic analysis of whole-genome sequences provided insights into the mobile genetic elements responsible for multi-drug resistance in these two strains of oxacillin-resistant and mecA-positive S. haemolyticus, which will assist clinicians in devising precise, personalized, and clinical therapeutic strategies for treating otitis media caused by multi-drug resistant S. haemolyticus.Keywords: Staphylococcus haemolyticus, ear swabs, mecA, antimicrobial resistance plasmid, whole genome sequence

ABSTRACTAn emergence of multidrug-resistant (MDR) Staphylococcus haemolyticus has been observed in the neonatal intensive care unit (NICU) of Nîmes University Hospital in southern France. A case–control analysis was conducted on 96 neonates, to identify risk factors associated with S. haemolyticus infection, focusing on clinical outcomes. Forty-eight MDR S. haemolyticus strains, isolated from neonates between October 2019 and July 2022, were investigated using routine in vitro procedures and whole-genome sequencing. Additionally, five S. haemolyticus isolates from adult patients were sequenced to identify clusters circulating within the hospital environment. The incidence of neonatal S. haemolyticus was significantly associated with low birth weight, lower gestational age, and central catheter use (p

Background: Staphylococcus haemolyticus is a clinically significant Coagulase Negative Staphylococci (CoNS) accountable for various infections and is often multi-drug resistant along with resistance to linezolid. Aim and Objectives: This study was carried out to detect the presence of cfr and optrA gene in clinical isolates of linezolid resistant S. haemolyticus in a tertiary care hospital. Material and Methods: A total of 227 clinical isolates of S. haemolyticus recovered from various clinical samples were tested to determine susceptibility to linezolid by phenotypic method. Further, the presence of cfr & optrA gene was looked for, in clinical isolates of S. haemolyticus. Results: S. haemolyticus was isolated predominantly from inpatient department mainly from blood culture (85%). Linezolid resistance was confirmed in 9.2% isolates of S. haemolyticus phenotypically and they were also methicillin resistant. On genotypic characterization, cfr gene could be detected in 7.04% the isolates. However, all the isolates were negative for optrA gene. Conclusion: Emergence of resistance to linezolid in S. haemolyticus was reported for the first time. The presence of cfr gene is the most common mechanism of resistance to linezolid. Correct identification of these isolates and adherence to strict infection control protocols will help in better clinical outcomes.

Background: Staphylococcus haemolyticus is a clinically significant Coagulase Negative Staphylococci (CoNS) accountable for various infections and is often multi-drug resistant along with resistance to linezolid. Aim and Objectives: This study was carried out to detect the presence of cfr and optrA gene in clinical isolates of linezolid resistant S. haemolyticus in a tertiary care hospital. Material and Methods: A total of 227 clinical isolates of S. haemolyticus recovered from various clinical samples were tested to determine susceptibility to linezolid by phenotypic method. Further, the presence of cfr & optrA gene was looked for, in clinical isolates of S. haemolyticus. Results: S. haemolyticus was isolated predominantly from inpatient department mainly from blood culture (85%). Linezolid resistance was confirmed in 9.2% isolates of S. haemolyticus phenotypically and they were also methicillin resistant. On genotypic characterization, cfr gene could be detected in 7.04% the isolates. However, all the isolates were negative for optrA gene. Conclusion: Emergence of resistance to linezolid in S. haemolyticus was reported for the first time. The presence of cfr gene is the most common mechanism of resistance to linezolid. Correct identification of these isolates and adherence to strict infection control protocols will help in better clinical outcomes. [ABSTRACT FROM AUTHOR]

Global warming have become a stress condition due to the generation of greenhouse gases from the burning of fossil fuels and deforestation with the industrial revolution. Climate change induces biotic and abiotic stress conditions which badly disturb the yield of crops with leading to the biochemical and physiological damages to plants. Therefore; this study investigated the capability of Morus alba L. wood biochar and plant growth promoting rhizobacteria PG1 (Pseudomonas sp.) and PG2 (Staphylococcus haemolyticus) to alleviate the drought condition in Brassica napus L. plant. In the current research work, the combined application of plant growth promoting rhizobacteria (PGPRs) and biochar triggered an enhancement in physicochemical properties of soil including %field capacity, water use efficiency, germination parameters including Timson germination index, final emergence percentage, mean germination time, final germination percentage, germination energy, mean emergence time, germination rate index and vegetative parameters including seed vigor indexes (SVI-I & SVI-II) and plant height stress index. Inoculation and co-inoculation of PGPRs and biochar positively promote the canola plant growth even under induce drought stress condition. A positive increase in B. napus biomass including leaf area, plant height and root growth and its dry and fresh mass at p

Abstract Background Staphylococcus haemolyticus (S. haemolyticus) is the main etiological factor in skin and soft tissue infections (SSTI). S. haemolyticus infections are an important concern worldwide, especially with the associated biofilms and drug resistance. Herein, we investigated the inhibitory effect of Flavaspidic acid BB obtained from plant extractions on clinical S. haemolyticus strains and their biofilms. Moreover, we predicted its ability to bind to the protein-binding site by molecular simulation. Since the combination of Hsp70 and RNase P synthase after molecular simulation with flavaspidic acid BB is relatively stable, enzyme-linked immunosorbent assay (ELISA) was used to investigate Hsp70 and RNase P synthase to verify the potential antimicrobial targets of flavaspidic acid BB. Results The minimum inhibitory concentrations (MIC) of flavaspidic acid BB on 16 clinical strains of S. haemolyticus was 5 ~ 480 µg/mL, and BB had a slightly higher inhibitory effect on the biofilm than MUP. The inhibitory effect of flavaspidic acid BB on biofilm formation was better with an increase in the concentration of BB. Molecular simulation verified its ability to bind to the protein-binding site. The combination of ELISA kits showed that flavaspidic acid BB promoted the activity of Hsp70 and inhibited the activity of RNase P, revealing that flavaspidic acid BB could effectively inhibit the utilization and re-synthesis of protein and tRNA synthesis, thus inhibiting bacterial growth and biofilm formation to a certain extent. Conclusions This study could potentially provide a new prospect for the development of flavaspidic acid BB as an antibacterial agent for resistant strains.

Wanyang Dong,1,* Qi Peng,1,* Xiaohua Tang,1,2,* Tian Zhong,1 Shunan Lin,1 Ziling Zhi,1 Jingyi Ye,1 Bixia Yang,1 Ning Sun,1,3 Wenchang Yuan1 1Guangzhou Key Laboratory for Clinical Rapid Diagnosis and Early Warning of Infectious Diseases, KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou, 510180, People’s Republic of China; 2Third Affiliated Hospital of Guangzhou Medical University, Department of Clinical Laboratory, Guangzhou, 510150, People’s Republic of China; 3Guangzhou First People’s Hospital, School of Medicine, South China University of Technology, Guangzhou, 510180, People’s Republic of China*These authors contributed equally to this workCorrespondence: Ning Sun; Wenchang Yuan, Email ning.sun@connect.polyu.hk; yuanwenchang95@163.comBackground: Staphylococcus haemolyticus is an opportunistic pathogen that belongs to coagulase-negative Staphylococci (CoNS). Increasing infection and multi-drug resistance cases caused by this strain have been reported and thus it poses a great health threat.Methods: The third-generation sequencing technology was performed on a S. haemolyticus SH-1 isolated from a clinical sample to analyze the drug resistance genes, which included vancomycin resistance related genes. In addition, antimicrobial susceptibility tests, transmission electron microscopy and Triton X-100 stimulated autolysis were conducted to understand its biological characteristics.Results: The study shows that this clinical isolate is a vancomycin intermediate-resistant strain. Genome comparison also revealed that WalK(N70K) and WalK(R280Q) mutations may contribute to the vancomycin resistant phenotype. Besides, S. haemolyticus SH-1 exhibit common features of thicker cell wall and decreased autolytic activity.Conclusion: S. haemolyticus SH-1 with WalKR mutations shows typical characteristics of vancomycin resistant strains. Combining the genome features and biological properties, our findings may provide important information for the understanding of the molecular mechanism of S. haemolyticus to vancomycin intermediate-resistance.Keywords: Staphylococcus haemolyticus, drug resistance gene, vancomycin intermediate-resistance, whole genome sequencing

Background Staphylococcus haemolyticus has emerged as an important multidrug-resistant nosocomial pathogen. Linezolid is useful in the treatment of severe infections caused by methicillin-resistant Staphylococci. Resistance to linezolid in Staphylococci is due to one or more of the following mechanisms: acquisition of the cfr (chloramphenicol florfenicol resistance) gene, mutation in the central loop of domain V of the 23S rRNA, and mutation in the rplC and rplD genes. This study was carried out to detect and characterize resistance to linezolid among the clinical isolates of Staphylococcus haemolyticus. Materials and Methods The study included 84 clinical isolates of Staphylococcus haemolyticus. Susceptibility to various antibiotics was determined by disc diffusion method. Minimum inhibitory concentration (MIC) was determined by agar dilution method for linezolid. Methicillin resistance was screened using oxacillin and cefoxitin disc. Polymerase chain reaction was done to detect mecA, cfr and mutations in the V domain of the 23S rRNA gene. Results Resistance to linezolid was exhibited by 3 of the 84 study isolates with MIC more than 128 µg/mL. The cfr gene was detected in all the three isolates. The G2603T mutation was observed in the domain V of the 23S rRNA among two isolates, whereas one isolate lacked any mutation. Conclusion The emergence and spread of linezolid-resistant Staphylococcus haemolyticus isolates carrying G2603T mutation in the domain V of the 23S rRNA and harboring the cfr gene pose a threat in clinical practice.

ABSTRACT Staphylococcus haemolyticus is an increasingly relevant nosocomial pathogen. The combination of multi-drug resistance and ability to form biofilms makes S. haemolyticus infections difficult to treat. Bacteriocins are ribosomally synthesized antimicrobial peptides produced by bacteria to inhibit growth of often closely related bacteria. Due to differences in the modes of action between bacteriocins and antibiotics, bacteriocins are normally equally potent against antibiotic-resistant and antibiotic-sensitive strains. To find bacteriocins able to inhibit S. haemolyticus and related species, clinical and commensal S. haemolyticus isolates (n = 174) were assayed for bacteriocin production. One commensal isolate produced an antimicrobial substance inhibiting S. haemolyticus and Staphylococcus aureus. The substance had physicochemical properties that are characteristic of bacteriocins. Purification, whole-genome sequencing, and mass spectrometry identified the antimicrobial as a novel two-peptide lantibiotic, hereafter named romsacin. The bacteriocin was active against a broad range of Gram-positive bacteria, such as the World Health Organization priority pathogens S. aureus [methicillin-resistant S. aureus (MRSA)] and Enterococcus faecium [vancomycin-resistant E. faecium (VRE)]. Importantly, the bacteriocin also eradicated S. haemolyticus, Staphylococcus epidermidis, MRSA, and VRE biofilms. IMPORTANCE Bacteria produce bacteriocins to inhibit growth of other bacterial species. We have studied the antimicrobial activity of a new bacteriocin produced by the skin bacterium S. haemolyticus. The bacteriocin is effective against several types of Gram-positive bacteria, including highly virulent and antibiotic-resistant strains such as Staphylococcus aureus and Enterococcus faecium. Effective antimicrobials are important for the treatment of infections and the success of major surgery and chemotherapy. Bacteriocins can be part of the solution to the global concern of antimicrobial resistance.

Background: Staphylococcus haemolyticus (S. haemolyticus) is the main etiological factor in skin and soft tissue infections (SSTI). S. haemolyticus infections are an important concern worldwide, especially with the associated biofilms and drug resistance. Herein, we investigated the inhibitory effect of Flavaspidic acid BB obtained from plant extractions on clinical S. haemolyticus strains and their biofilms. Moreover, we predicted its ability to bind to the protein-binding site by molecular simulation. Since the combination of Hsp70 and RNase P synthase after molecular simulation with flavaspidic acid BB is relatively stable, enzyme-linked immunosorbent assay (ELISA) was used to investigate Hsp70 and RNase P synthase to verify the potential antimicrobial targets of flavaspidic acid BB. Results: The minimum inhibitory concentrations (MIC) of flavaspidic acid BB on 16 clinical strains of S. haemolyticus was 5 ~ 480 µg/mL, and BB had a slightly higher inhibitory effect on the biofilm than MUP. The inhibitory effect of flavaspidic acid BB on biofilm formation was better with an increase in the concentration of BB. Molecular simulation verified its ability to bind to the protein-binding site. The combination of ELISA kits showed that flavaspidic acid BB promoted the activity of Hsp70 and inhibited the activity of RNase P, revealing that flavaspidic acid BB could effectively inhibit the utilization and re-synthesis of protein and tRNA synthesis, thus inhibiting bacterial growth and biofilm formation to a certain extent. Conclusions: This study could potentially provide a new prospect for the development of flavaspidic acid BB as an antibacterial agent for resistant strains. [ABSTRACT FROM AUTHOR]

ABSTRACT Staphylococcus haemolyticus (S. haemolyticus) is a coagulase-negative Staphylococcus that has become one of the primary causes of nosocomial infection. After a long period of antibiotic use, S. haemolyticus has developed multiple resistance phenotypes for macrolides and lincosamides. Herein, we evaluated four S. haemolyticus clinical isolates, of which three had antibiotic resistance patterns reported previously. The fourth isolate was resistant to both erythromycin and clindamycin in the absence of erythromycin induction. This novel phenotype, known as constitutive macrolides-lincosamides-streptogramins resistance, has been reported in other bacteria but has not been previously reported in S. haemolyticus. Investigation of the isolate demonstrated a deletion in the methyltransferase gene ermC, upstream leader peptide. This deletion resulted in constitutive MLS resistance based on whole-genome sequencing and experimental verification. Continuous expression of ermC was shown to inhibit the growth of S. haemolyticus, which turned out to be the fitness cost with no MLS pressure. In summary, this study is the first to report constitutive MLS resistance in S. haemolyticus, which provides a better understanding of MLS resistance in clinical medicine. Importance This study identified a novel phenotype of macrolides/lincosamides resistance in Staphylococcus haemolyticus which improved a better guidance for clinical treatment. It also clarified the mechanistic basis for this form of antibiotic resistance that supplemented the drug resistance mechanism of Staphylococcus. In addition, this study elaborated on a possibility that continuous expression of some resistance genes was shown to inhibit the growth of bacteria themselves, which turned out to be the fitness cost in the absence of antibiotic pressure.

Background: Staphylococcus haemolyticus is a coagulase‐negative commensal organism of both people and companion animals. It has pathogenic potential and when cultured is often meticillin‐ and multidrug‐resistant. Objectives: To characterise the clinical features of dogs and cats with clinical skin disease that had positive S. haemolyticus skin cultures, and to employ whole‐genome sequencing (WGS) to identify resistance genes and characterise the genetic relatedness of strains. Materials and Methods: Isolates were identified by the institutional clinical microbiology laboratory by routine aerobic culture and susceptibility from seven veterinary hospitals across the United States. Then, WGS and analysis of each isolate were performed and clinical data collected via a retrospective clinician questionnaire. Results: S. haemolyticus was identified from superficial (seven of 12) and deep (five of 12) cutaneous infections in our study. Most animals had received antimicrobials (10 of 12) and/or immunomodulatory drugs (nine of 12) within the six months before culture. WGS analysis revealed a variety of genetic lineages and a wide array of antimicrobial resistance genes. Meticillin resistance was identified in nine of 12 isolates and four of 12 isolates demonstrated mupirocin tolerance. Conclusions and Clinical Relevance: Staphylococcus haemolyticus may be an under‐recognised pathogen in companion animals, and its demonstrated potential for multidrug‐resistance, meticillin‐resistance, and high‐level mupirocin tolerance may create a therapeutic challenge. Further studies should evaluate the prior antimicrobial use and immunocompromised status as risk factors for infection with S. haemolyticus. [ABSTRACT FROM AUTHOR]

Background and Aim: The treatment of bacterial infections especially of the family Staphylococcaceae is a major health burden that has led to economic losses, high morbidity, and mortality rates globally. This study aimed at the isolation and characterization of coagulase-positive, methicillin, and multi-drug-resistant Staphylococci isolated from wounds of patients. Materials and Methods: Forty-five wound swabs were collected using sterile swab sticks. Isolation was done by streaking technique on mannitol salt agar. The isolates obtained were screened for methicillin and multi-drug resistance using the disk diffusion method. Biochemical and molecular characteristics using the 16S rDNA gene were used to identify the selected isolates. Results: Four Staphylococci isolates resistant to methicillin (0.00 mm to 9.0 mm) were selected out of thirty-one. Reactions to catalase and coagulase productions were positive. Three out of the four isolates were identified using their 16S rDNA genes and they were found to be closely related to other family members of Staphylococcaceae at GenBank. The fourth isolate was identified using its biochemical characteristics as Staphylococcus spp. HFS4. The three identified isolates were M. sciuri HFS1 (ON340756), M. sciuri HFS3 (ON340770), and S. haemolyticus HFS2 (ON358435). The four isolates were resistant to more than five antibiotics that cut across all the classes of antibiotics. The multiple antimicrobial indices were between 0.5 and 0.8. Conclusion: There is a need for regular antimicrobial resistance surveillance within the hospital environment, earlier detection and correct prescription of potent antimicrobials will check the spread of Staphylococcus infections and their virulent genes. [ABSTRACT FROM AUTHOR]

BackgroundStaphylococcus haemolyticus has emerged as an important multidrug-resistant nosocomial pathogen. Linezolid is useful in the treatment of severe infections caused by methicillin-resistant Staphylococci. Resistance to linezolid in Staphylococci is due to one or more of the following mechanisms: acquisition of the cfr (chloramphenicol florfenicol resistance) gene, mutation in the central loop of domain V of the 23S rRNA, and mutation in the rplC and rplD genes. This study was carried out to detect and characterize resistance to linezolid among the clinical isolates of Staphylococcus haemolyticus. Materials and Methods The study included 84 clinical isolates of Staphylococcus haemolyticus. Susceptibility to various antibiotics was determined by disc diffusion method. Minimum inhibitory concentration (MIC) was determined by agar dilution method for linezolid. Methicillin resistance was screened using oxacillin and cefoxitin disc. Polymerase chain reaction was done to detect mecA, cfr and mutations in the V domain of the 23S rRNA gene. Results Resistance to linezolid was exhibited by 3 of the 84 study isolates with MIC more than 128 µg/mL. The cfr gene was detected in all the three isolates. The G2603T mutation was observed in the domain V of the 23S rRNA among two isolates, whereas one isolate lacked any mutation. Conclusion The emergence and spread of linezolid-resistant Staphylococcus haemolyticus isolates carrying G2603T mutation in the domain V of the 23S rRNA and harboring the cfr gene pose a threat in clinical practice. [ABSTRACT FROM AUTHOR]

Abstract Background Coagulase-negative staphylococci can cause hospital-acquired infections, especially in immunocompromised hosts. Bacterial meningitis is a potentially fatal infection of the central nervous system, causing high mortality and morbidity. In general, the causative agents of meningitis, coagulase-negative staphylococci, are associated with direct implantation of a foreign body and the presence of a cerebrospinal fluid (CSF) shunt. Here, we describe a case of nosocomial meningitis caused by Staphylococcus haemolyticus in a child with neutropenia who had no intracranial foreign devices. Case presentation A 15-year-old boy with relapsed acute myeloid leukemia undergoing chemotherapy through a central venous catheter developed fever on Day 13 post-initiation of chemotherapy. There was no history of implantation of neurosurgical devices. Two blood cultures obtained on Day 14 were positive for Staphylococcus haemolyticus. Clinical improvement was noted, and treatment with vancomycin and removal of the central venous catheter resulted in negative repeat blood cultures on Day 18. However, the patient developed a tendency for somnolence and improper speech, along with persistent fever on Day 26. A lumber puncture was performed on Day 27, resulting in positive culture of Staphylococcus haemolyticus. He was diagnosed with meningitis and the dosage of vancomycin was increased. A repeat CSF culture was positive for Staphylococcus haemolyticus on Day 40, so oral rifampicin was added. CSF findings on Day 46 revealed a low concentration of vancomycin, and treatment was switched from vancomycin plus rifampicin to linezolid. After Day 46, four subsequent cerebrospinal fluid tests of the CSF showed no growth of Staphylococcus haemolyticus. The patient’s symptoms were improved on Day 52. Brain and spinal magnetic resonance images was taken and it showed no abnormalities. Linezolid was continued until Day 72. The patient was discharged without any complications on Day 72. Conclusions To the best of our knowledge, this is the first reported case of Staphylococcus haemolyticus meningitis in a patient without a neurosurgical device. Typical symptoms or signs may be absent in a patient with meningitis who also has neutropenia. Repeated tests of the CSF, and prolonged duration of antibiotics should be considered if atypical pathogens are detected in immunocompromised hosts.

Introduction. It has been established in an animal model that coagulase-negative staphylococci (Staphylococcus haemolyticus) and anaerobes (Peptococcus niger) cause the development of an acute inflammatory process in the prostate when inoculated with 103 CFU/ml. At the same time, data have been published indicating the pathogenic potential of these microorganisms on a titer of 102 CFU/ml. But it was confirmed for the model of acute obstructive pyelonephritis. In addition, the characteristics of the formation of the inflammatory response at different times were determined, which require detailed verification and comparative characteristics with those during infection with a causative uropathogen (Escherichia coli).Objective. Based on the results of the experiment, to carry out: 1) an evaluation of the relationship between the dynamics of microbial load and the degree of pathomorphological changes in prostate tissues during infection with various uropathogens in a titer of 103 CFU/ml; 2) an evaluation of the degree of microbial load and severity of histological changes in prostate tissues on follow-up day 7 with transurethral infection with various uropathogens in a subpathogenic titer of 102 CFU/ml; 3) a fundamental comparative analysis of the indicators of contamination and the severity of inflammatory changes on follow-up day 7 after the inoculation of various uropathogens in titers of 102 and 103 CFU/ml.Materials and methods. The animal model was performed using the FELASA and ARRIVE guidelines. Lab animals: 20 New Zealand rabbits. Uropathogens: E. coli, S. haemolyticus, and P. niger. Infectious titers: 102.3 cfu/ml. Uropathogen inoculation technique: topical transurethral. Randomization: all laboratory animals were divided into 4 groups depending on the uropathogen (3 experimental, 1 control). Follow-up periods: day 1, 3, 7 and 14 for a titer of 103 CFU/ml, and day 7 for a titer of 102 CFU/ml. At the end of the follow-up, euthanasia and autopsy were performed with the extraction of the urogenital organ complex. Hereafter, biopsies were taken from various parts of the prostate. Cultural and histological studies of prostate tissues were carried out using standard methods. The results were analyzed using Statistica 10.2 (StatSoft Inc., Tulsa, OK, USA) and GraphPad Prism 9 (GraphPad Software Inc., Graphpad Holdings LLC, San Diego, CA, USA) programs through descriptive and nonparametric statistics.Results. Bacterial contamination of prostate tissue was determined in all cases of infection with differences (p 0.05) differences were found both in cases of infection with a titer of 103 CFU/ml, and when compared with the data on contamination for a test titer of 102 CFU/ml, at the same time observations. At once, when E. coli and S. haemolyticus were infected at a subpathogenic titer of 102 CFU/ml, inflammatory changes were recorded that had a mild diffuse character, in relation to those after inoculation of these pathogens in a titer of 103 CFU/ml. In turn, P. niger induced the development of low-intensity focal alteration in isolated areas of prostate tissues.Conclusions. Detailed analysis of culture and histological data showed that E. coli, S. haemolyticus and P. niger have significant pathogenic potential at titer of 103 CFU/ml. In turn, when the titer decreases to 102 CFU/ml, E. coli and S. haemolyticus retain their pathogenic potential, but the severity of the inflammatory reaction is significantly reduced. It was also found that a change in bacterial contamination affects the severity of the inflammatory process in all groups during seven follow-up days at a given test titer.

Background and Aim: Staphylococcus haemolyticus is a prominent pathogen in hospital-related infections, exhibiting high antibiotic resistance. This study aimed to investigate antibiotic sensitivity, biofilm formation, and the presence of virulenceassociated genes in S. haemolyticus isolated from pregnant women with urinary tract infections. Materials and Methods: Clinical samples were collected from pregnant women with urinary tract infections between October 2021 and December 2022. S. haemolyticus isolates were identified using cultural, biochemical, and molecular methods. Antibiotic susceptibility was determined using the VITEK-2 system. Biofilm formation was assessed, and virulenceassociated genes (hla, hlb, fnbA, and fnbB) were detected using PCR. Results: Among 260 clinical samples, 36 S. haemolyticus isolates were identified. The isolates exhibited high resistance to Benzylpencillin, Erythromycin, oxacillin, Trimethoprim/sulfamethoxazole, Levofloxacin, and Gentamicin. Resistance was lower to Tigecycline, linezolid, tobramycin, Rifampin, vancomycin, Moxifloxacin, Tetracycline, and Ticoplanin. Biofilm formation was negative in 69.4% and weak in 30.6% of isolates. The hla gene was present in all isolates, while hlb was detected in 77.7%. Detection rates of fnbA and fnbB were 88.8% and 38.8%, respectively. Conclusion: This study highlights the high antibiotic resistance, limited biofilm formation ability, and prevalence of virulence-associated genes in S. haemolyticus isolates from pregnant women with urinary tract infections. These findings underscore the clinical significance of this bacterium and the need for infection control measures. [ABSTRACT FROM AUTHOR]

Introduction: Coagulase negative staphylococci (CoNS) are the most frequent blood culture isolates and an important cause of nosocomial blood stream infections especially in catheterised patients. CoNS are also the most common contaminants of blood cultures and are proven to be especially problematic. These uncertainties may result in over diagnosis and indirect overuse of antimicrobials especially vancomycin. Aim: To determine the clinical significance of CoNS isolated from blood culture of patients admitted in a tertiary care hospital. Materials and Methods: A prospective cross-sectional study was conducted in Bharati Hospital Research Center, Pune, Maharashtra, India, from August 2019 to July 2020 (One year). Patients whose paired/multiple blood culture samples showed pure growth of CoNS were included in the study. CoNS were identified by Vitek 2 system and antimicrobial susceptibility was reported. Clinical history of all patients was taken who showed pure growth of CoNS in either one or multiple sites of the automated blood culture bottles. Isolated CoNS were considered as pathogen only if clinical and laboratory parameters are fulfilled. Chi-square test was used to find out statistical significance of isolated pathogenic CoNS. Results: A total 147 CoNS isolated from blood cultures of suspected patients of sepsis were included in study. About 23 (15.6%) CoNS were isolated from both the sites. Remaining 124 (84.4%) CoNS were isolated from single site. CoNS were considered as pathogen in all 23 cases based on clinical and laboratory criteria. The most frequent isolated CoNS was S. haemolyticus 7 (30.4%), followed by S. epidermidis 5 (21.7%), S. hominis 3 (13.1%) , S. lugdunensis 3 (13.1%), S. scuiri 2 (8.7%), S. xylosus 1 (4.3%), S. caprae 1 (4.3%), S. capitis 1 (4.3%). Methicillin resistance was observed in 15 (65.2%) CoNS strains. Conclusion: Patients suffering from CoNS from their blood stream should be carefully evaluated clinically. Proper blood collection techniques need to be followed to avoid contamination of blood culture samples and to avoid diagnostic dilemma.

Background: Coagulase-negative staphylococci can cause hospital-acquired infections, especially in immunocompromised hosts. Bacterial meningitis is a potentially fatal infection of the central nervous system, causing high mortality and morbidity. In general, the causative agents of meningitis, coagulase-negative staphylococci, are associated with direct implantation of a foreign body and the presence of a cerebrospinal fluid (CSF) shunt. Here, we describe a case of nosocomial meningitis caused by Staphylococcus haemolyticus in a child with neutropenia who had no intracranial foreign devices. Case presentation: A 15-year-old boy with relapsed acute myeloid leukemia undergoing chemotherapy through a central venous catheter developed fever on Day 13 post-initiation of chemotherapy. There was no history of implantation of neurosurgical devices. Two blood cultures obtained on Day 14 were positive for Staphylococcus haemolyticus. Clinical improvement was noted, and treatment with vancomycin and removal of the central venous catheter resulted in negative repeat blood cultures on Day 18. However, the patient developed a tendency for somnolence and improper speech, along with persistent fever on Day 26. A lumber puncture was performed on Day 27, resulting in positive culture of Staphylococcus haemolyticus. He was diagnosed with meningitis and the dosage of vancomycin was increased. A repeat CSF culture was positive for Staphylococcus haemolyticus on Day 40, so oral rifampicin was added. CSF findings on Day 46 revealed a low concentration of vancomycin, and treatment was switched from vancomycin plus rifampicin to linezolid. After Day 46, four subsequent cerebrospinal fluid tests of the CSF showed no growth of Staphylococcus haemolyticus. The patient's symptoms were improved on Day 52. Brain and spinal magnetic resonance images was taken and it showed no abnormalities. Linezolid was continued until Day 72. The patient was discharged without any complications on Day 72. Conclusions: To the best of our knowledge, this is the first reported case of Staphylococcus haemolyticus meningitis in a patient without a neurosurgical device. Typical symptoms or signs may be absent in a patient with meningitis who also has neutropenia. Repeated tests of the CSF, and prolonged duration of antibiotics should be considered if atypical pathogens are detected in immunocompromised hosts. [ABSTRACT FROM AUTHOR]

ABSTRACT Staphylococcus haemolyticus is a major cause of late-onset sepsis in neonates, and endemic clones are often multidrug-resistant. The bacteria can also act as a genetic reservoir for more pathogenic bacteria. Molecular epidemiology is important in understanding bacterial pathogenicity and preventing infection. To describe the molecular epidemiology of S. haemolyticus isolated from neonatal blood cultures at a Swedish neonatal intensive care unit (NICU) over 4 decades, including antibiotic resistance genes (ARGs), virulence factors, and comparison to international isolates. Isolates were whole-genome sequenced, and single nucleotide polymorphisms in the core genome were used to map the relatedness. The occurrence of previously described ARGs and virulence genes were investigated. Disc diffusion and gradient tests were used to determine phenotypic resistance. The results revealed a clonal outbreak of S. haemolyticus at this NICU during the 1990s. Multidrug resistance was present in 28 (82%) of all isolates and concomitant resistance to aminoglycoside and methicillin occurred in 27 (79%). No isolates were vancomycin resistant. Genes encoding ARGs and virulence factors occurred frequently. The isolates in the outbreak were more homogenous in their genotypic and phenotypic patterns. Genotypic and phenotypic resistance combinations were consistent. Pathogenic traits previously described in S. haemolyticus occurred frequently in the present isolates, perhaps due to the hospital selection pressure resulting in epidemiological success. The clonal outbreak revealed by this study emphasizes the importance of adhering to hygiene procedures in order to prevent future endemic outbreaks. IMPORTANCE This study investigated the relatedness of Staphylococcus haemolyticus isolated from neonatal blood and revealed a clonal outbreak in the 1990s at a Swedish neonatal intensive care unit. The outbreak clone has earlier been isolated in Japan and Norway. Virulence and antibiotic resistance genes previously associated with clinical S. haemolyticus were frequently occuring in the present study as well. The majority of the isolates were multidrug-resistant. These traits should be considered important for S. haemolyticus epidemiological success and are probably caused by the hospital selection pressure. Thus, this study emphasizes the importance of restrictive antibiotic use and following the hygiene procedures, to prevent further antibiotic resistance spread and future endemic outbreaks.

Introduction: The burden of community acquired antibiotic resistance is increasing with an alarming rate in the developing countries. Many factors, including inappropriate use of antibiotics, have been suggested as the causes of spread of resistant strains in the community. Aim: To compare antibiotics susceptibility pattern of community acquired gram positive isolates among women of reproductive age with history of recent inappropriate antibiotics use and those with no history of antibiotics use. Materials and Methods: The present study was a cross-sectional descriptive study carried out from August 2020 to February 2021 at the State Teaching Hospital in Enugu, Nigeria. The participants for the study were 713 apparently healthy women who presented to the family planning unit for preconception care. All the participants were screened for asymptomatic bacteriuria by culturing their Midstream Urine (MSU). The isolated organisms were identified, and Antimicrobial Susceptibility (AST) test performed using the Vitek 2. Polymerase Chain Reaction (PCR) was done for the presence of mecA gene among methicillin resistant Staphylococcus species. The antibiotic susceptibility pattern of the isolates from participants with positive history of recent antibiotic use was compared with the susceptibility pattern of those with no history of antibiotics using Chi-square test. Results: Out of the 713 participants, 59 (8.3%) had a positive history of recent antibiotics use. Only 1 (1.7%) participant had her antibiotics prescribed by the doctor while 13 (22) and 45 (76.3) obtain their antibiotics at the patent medicine dealer shop and through self-medication respectively. The commonest indication for inappropriate use was febrile illness followed by upper respiratory symptoms. Ciprofloxacin was the most abused antibiotics followed by amoxicillin-clavulanic acid. Twenty (83.3%) and 4 (16.7%) had Asymptomatic Bacteriuria (ASB) among those with recent antibiotic use and those with no history of recent antibiotic use respectively. All the Methicillin Resistant Staphylococcus aureus (MRSA) was isolated from the participants with recent history of inappropriate antibiotic use. Also, of significant among this group were quinolone resistant gram positive organisms. Conclusion: ASB and multidrug resistant gram positive isolates were common among the participants with recent history of inappropriate antibiotic use. There is need to regulate antibiotics use in the community to prevent selection of multidrug resistant organisms. [ABSTRACT FROM AUTHOR]

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Background: For years, coagulase-negative staphylococci (CoNS) were not considered a cause of bloodstream infections (BSIs) and were often regarded as contamination. However, the association of CoNS with nosocomial infections is increasingly recognized. The identification of more than 40 different CoNS species has been driven by the introduction of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Yet, treatment guidelines consider CoNS as a whole group, despite increasing antibiotic resistance (ABR) in CoNS. This retrospective study provides an in-depth data analysis of CoNS isolates found in human blood culture isolates between 2013 and 2019 in the entire region of the Northern Netherlands. Methods: In total, 10,796 patients were included that were hospitalized in one of the 15 hospitals in the region, leading to 14,992 CoNS isolates for (ABR) data analysis. CoNS accounted for 27.6% of all available 71,632 blood culture isolates. EUCAST Expert rules were applied to correct for errors in antibiotic test results. Results: A total of 27 different CoNS species were found. Major differences were observed in occurrence and ABR profiles. The top five species covered 97.1% of all included isolates: S. epidermidis, S. hominis, S. capitis, S. haemolyticus, and S. warneri. Regarding ABR, methicillin resistance was most frequently detected in S. haemolyticus (72%), S. cohnii (65%), and S. epidermidis (62%). S. epidermidis and S. haemolyticus showed 50–80% resistance to teicoplanin and macrolides while resistance to these agents remained lower than 10% in most other CoNS species. Conclusion: These differences are often neglected in national guideline development, prompting a focus on 'ABR-safe' agents such as glycopeptides. In conclusion, this multi-year, full-region approach to extensively assess the trends in both the occurrence and phenotypic resistance of CoNS species could be used for evaluating treatment policies and understanding more about these important but still too often neglected pathogens. [ABSTRACT FROM AUTHOR]

Although Staphylococcus haemolyticus and Staphylococcus lugdunensis are members of the normal human flora, they also can cause infection. Here, we present the draft genomes of five strains of S. lugdunensis and one strain of S. haemolyticus isolated from transurethral catheterized urine samples from different females experiencing lower urinary tract symptoms., Competing Interests: The authors declare no conflict of interest.

Introduction: The burden of community acquired antibiotic resistance is increasing with an alarming rate in the developing countries. Many factors, including inappropriate use of antibiotics, have been suggested as the causes of spread of resistant strains in the community. Aim: To compare antibiotics susceptibility pattern of community acquired gram positive isolates among women of reproductive age with history of recent inappropriate antibiotics use and those with no history of antibiotics use. Materials and Methods: The present study was a cross-sectional descriptive study carried out from August 2020 to February 2021 at the State Teaching Hospital in Enugu, Nigeria. The participants for the study were 713 apparently healthy women who presented to the family planning unit for preconception care. All the participants were screened for asymptomatic bacteriuria by culturing their Midstream Urine (MSU). The isolated organisms were identified and Antimicrobial Susceptibility (AST) test performed using the Vitek 2. Polymerase Chain Reaction (PCR) was done for the presence of mecA gene among methicillin resistant Staphylococcus species. The antibiotic susceptibility pattern of the isolates from participants with positive history of recent antibiotic use was compared with the susceptibility pattern of those with no history of antibiotics using Chi-square test. Results: Out of the 713 participants, 59 (8.3%) had a positive history of recent antibiotics use. Only 1 (1.7%) participant had her antibiotics prescribed by the doctor while 13 (22%) and 45 (76.3%) obtain their antibiotics at the patent medicine dealer shop and through self-medication respectively. The commonest indication for inappropriate use was febrile illness followed by upper respiratory symptoms. Ciprofloxacin was the most abused antibiotics followed by amoxicillin-clavulanic acid. A 20 (83.3%) and 4 (16.7%) had Asymptomatic Bacteriuria (ASB) among those with recent antibiotic use and those with no history of recent antibiotic use respectively. All the Methicillin Resistant Staphylococcus aureus (MRSA) was isolated from the participants with recent history of inappropriate antibiotic use. Also, of significant among this group were quinolone resistant gram positive organisms. Conclusion: The ASB and multidrug resistant gram positive isolates were common among the participants with recent history of inappropriate antibiotic use. There is need to regulate antibiotics use in the community to prevent selection of multidrug resistant organisms.

We report in this study for the first time the prevalence of multiple resistant Staphylococcus haemolyticus in clinical settings in Saudi Arabia. A total of 1060 clinical specimens of hospitalized patients were screened for the presence of S. haemolyticus in the period between September and December 2020. Primary identification of the isolates was carried out by colonial characteristics on mannitol salt agar and clumping factor test, confirmation of presumptive isolates and antimicrobial susceptibility testing was performed by Vitek® 2, while PCR was employed to detect mecA and vanA genes. A total of 20 S. haemolyticus isolates were recovered from 20 samples (blood cultures, urine, nasal swab, wound swab, groin swab, and axilla swab), 90% (P

• The majority of strains were biofilm producers. • About 5 % and 43 % of S. haemolyticus isolates were able to create strong and moderate biofilm, respectively. • There is a correlation between biofilm formation and antibiotic resistance. • vancomycin, gentamicin, and ciprofloxacin at sub-inhibitory concentrations of antibiotics tended to promote biofilm formation in most strains. This study aimed to establish the correlation between antibiotic resistance and biofilm formation by Staphylococcus haemolyticus and to examine the impact of sub-inhibitory concentrations of antibiotics (sub-MICs) on biofilm formation. Antibiotic susceptibility testing was conducted using the disk diffusion method, and biofilm formation was determined using Congo red agar and microtiter plate methods. Antibiotic resistance and biofilm-associated genes were detected using polymerase chain reaction. The majority of the twenty-one S. haemolyticus isolates were multidrug-resistant, methicillin-resistant (MRSH) and biofilm producers, including 43 % of moderate biofilm producers. A significant correlation was observed between MRSH and MSSH isolates in terms of biofilm production. Vancomycin, gentamicin, and ciprofloxacin at their sub-MICs tended to promote biofilm formation. The eno gene was present in 76.2 % of strains, followed by aap , and atlE. This study revealed a strong correlation between the biofilm-forming ability and antibiotic resistance in S. haemolyticus , which underlines a crucial public health issue. [ABSTRACT FROM AUTHOR]

ABSTRACT Staphylococcus haemolyticus and Staphylococcus hominis subsp. hominis are common coagulase-negative staphylococcus opportunistic pathogens. In Thailand, the clinical strains S. haemolyticus 1864 and 48 and S. hominis subsp. hominis 384 and 371 have been recovered from sick dogs. These strains were methicillin resistant with the nontypeable staphylococcal cassette chromosome mec (NT-SCCmec). The SCCmec element distribution in the clinical isolates from dogs was analyzed using whole-genome sequencing, which revealed the presence of different SCCmec composite islands (CIs) and gene structure. The SCCmec-CIs of ψSCCmec1864 (13 kb) and ψSCC1864 (11 kb) with a class C1 mec complex but no ccr gene were discovered in S. haemolyticus 1864. The CIs of ψSCCmec48 with a C1 mec complex (28 kb), SCC48 with ccrA4B4 (23 kb), and ψSCC48 (2.6 kb) were discovered in S. haemolyticus 48. In SCC48, insertion sequence IS256 contained an aminoglycoside-resistant gene [aph(2″)-Ia]. Two copies of IS431 containing the tetracycline-resistant gene tet(K) were found downstream of ψSCC48. In S. hominis subsp. hominis, the SCCmec-CI in strain 384 had two separate sections: ψSCCmec384 (20 kb) and SCCars (23 kb). ψSCCmec384 lacked the ccr gene complex but carried the class A mec complex. Trimethoprim-resistant dihydrofolate reductase (dfrC) was discovered on ψSCCmec384 between two copies of IS257. In strain 371, SCCmec VIII (4A) (37 kb) lacking a direct repeat at the chromosomal end was identified. This study found SCCmec elements in clinical isolates from dogs that were structurally complex and varied in their genetic content, with novel organization. IMPORTANCE In Thailand, the staphylococcal cassette chromosome mec (SCCmec) element, which causes methicillin resistance through acquisition of the mec gene, has been studied in clinical coagulase-negative Staphylococcus isolates from various companion animals, and Staphylococcus haemolyticus and Staphylococcus hominis subsp. hominis were found to have the most nontypeable (NT)-SCCmec elements. These species are more prone to causing illness and more resistant to a variety of antimicrobials than other coagulase-negative staphylococci. However, full characterization of NT-SCCmec in clinical S. haemolyticus and S. hominis subsp. hominis isolates from such animals has been limited. Our findings support the use of full nucleotide sequencing rather than PCR designed for Staphylococcus aureus in further research of novel SCCmec elements. Moreover, several antimicrobial resistance and heavy metal resistance genes were identified on the SCCmec elements; these are important as they could limit the therapeutic options available in veterinary medicine.

ABSTRACT Staphylococcus haemolyticus is an opportunistic pathogen associated with hospital-acquired infections. However, the genetic diversity of S. haemolyticus among the patients and the hospital environment is largely unknown. Here, we isolated 311 S. haemolyticus strains from different sampling sites of patients and hospital environment. Genomic analysis showed that ST42 is an emerging clone widely disseminated in the hospital. S. haemolyticus ST42 strains exhibited decreased susceptibilities for multiple antibiotics compared with other STs and carried significantly more antibiotic resistance genes (ARGs). Furthermore, ST42 strains harbored more virulence genes per isolate than in other STs, and the capsular biosynthesis genes capDEFG were more prevalent in ST42 strains. Using the Galleria mellonella infection model, we demonstrated that ST42 strains are highly virulent compared with non-ST42 strains. Taken together, our data identified an emerging ST42 clone of S. haemolyticus with aggregated ARGs and virulence determinants in the hospital, representing a significant health threat in terms of both disease and treatment. IMPORTANCE S. haemolyticus is an emerging opportunistic pathogen with a high burden of antimicrobial resistance. We performed molecular epidemiological analysis of S. haemolyticus that was isolated from a hospital, and found that the phylogenetic lineages are diverse accompanied by a dominant epidemic clonal lineage ST42. We demonstrated that S. haemolyticus ST42 strains have been disseminated among patients and the hospital environment. The data provide mechanistic insight and indicate that S. haemolyticus ST42 strains are multidrug-resistance and virulent clones via accumulating more ARGs and virulence genes.

ABSTRACT: Mastitis is a multifactorial disease and considered one of the most critical problems in the dairy industry worldwide. The condition is characterized by reduced milk and several abnormalities in the mammary gland. This study aimed to report an outbreak of gangrenous mastitis caused by multidrug-resistant Staphylococcus haemolyticus in a Santa Inês sheep herd. Eighteen sheep were affected, and five of them with severe clinical pictures were examined. The clinical and pathological picture were variable and characterized by apathy, anorexia, emaciation, opaque and brittle hair, apparent and congested episcleral vessels, and hyperthermia. These ewes had enlarged, firm, and painful mammary glands. Macroscopically, these lesions consisted of severe gangrenous mastitis, and microscopically, the primary lesions consisted of necrosis, thrombosis, and fibrosis of the mammary parenchyma. Milk samples from one of the five severely affected ewes were collected and cultured under aerobic or microaerophilic incubation at 37°C for 24 hours on sheep blood agar. The obtained colonies were then submitted to MALDI-TOF for speciation. The colonies were also submitted to an antimicrobial susceptibility test, genotyping of virulence factors and resistance genes were also performed. The isolates showed antimicrobial multiresistance since they were resistant to seven out of 13 tested antibiotics. The isolates were also positive for two staphylococcal enterotoxigenic genes (sec and see) and fibronectin-binding protein B (fnbB).

Staphylococcus haemolyticus is a cause of bovine mastitis, leading to inflammation in the mammary gland. This bacterial infection adversely affects animal health, reducing milk quality and yield. Its emergence has been widely reported, representing a significant economic loss for dairy farms. Interestingly, S. haemolyticus exhibits higher levels of antimicrobial resistance than other coagulase-negative Staphylococci. In this study, we synthesized silver/silver chloride nanoparticles (Ag/AgCl-NPs) using Solanum lasiocarpum root extract and evaluated their antibacterial and antibiofilm activities against S. haemolyticus. The formation of the Ag/AgCl-NPs was confirmed using UV–visible spectroscopy, which revealed maximum absorption at 419 nm. X-ray diffraction (XRD) analysis demonstrated the crystalline nature of the Ag/AgCl-NPs, exhibiting a face-centered cubic lattice. Fourier transform infrared (FT-IR) spectroscopy elucidated the functional groups potentially involved in the Ag/AgCl-NPs synthesis. Transmission electron microscopy (TEM) analysis revealed that the average particle size of the Ag/AgCl-NPs was 10 nm. Antimicrobial activity results indicated that the minimum inhibitory concentration (MIC) and maximum bactericidal concentration (MBC) of the Ag/AgCl-NPs treatment were 7.82–15.63 μg/mL towards S. haemolyticus. Morphological changes in bacterial cells treated with the Ag/AgCl-NPs were observed under scanning electron microscopy (SEM). The Ag/AgCl-NPs reduced both the biomass of biofilm formation and preformed biofilm by approximately 20.24–94.66 % and 13.67–88.48 %. Bacterial viability within biofilm formation and preformed biofilm was reduced by approximately 21.56–77.54 % and 18.9–71.48 %, respectively. This study provides evidence of the potential of the synthesized Ag/AgCl-NPs as an antibacterial and antibiofilm agent against S. haemolyticus. • Ag/AgCl-NPs were synthesized using S. lasiocarpum root extract. • Ag/AgCl-NPs showed potent antibacterial and antibiofilm activity. • Ag/AgCl-NPs reduced biofilm biomass and bacterial cell viability. [ABSTRACT FROM AUTHOR]

Staphylococcus haemolyticus is an opportunistic skin pathogen and a frequent staphylococcal etiological agent. Staphylococcus haemolyticus is the most isolated coagulase negative Staphylococcus (CoNS) species. As a nosocomial infection agent, S. haemolyticus may adapt to the hospital environment and medical equipment. S.haemolyticus is a frequent colonizer of humans and animals, but has received less research than other Staphylococcus species. This study's goal was to test antibiotic susceptibility, biofilm forming abilities, and virulence related genes (hla, hlb, fnbA and fnbB) in S. haemolyticus. From December 2020 to February 2021, S. haemolyticus was isolated from clinical samples. The VITEK 2 compact system confirmed the identification of S.haemolyticus based on culture, biochemical, and API staph characteristics. Out of 260 samples, 36 (13.8%) had S.haemolyticus. Sixty-six percent of the 36 isolates came from urine, whereas 34 % came from wound swabs. S. haemolyticus isolates had the highest resistance to Benzylpencillin (100%) followed by Erythromycin (88.8%), Oxacillin (80.55%), Trimethoprim/sulfamethoxazole (80.55%), Levofloxacin (72.22%) and Gentamicin (55.55%). Biofilm forming capacity was negative in 69.4% of isolates, weak in 30.64%, and strong in none. Detection of hemolysin genes (hla and hlb) and Fibronectin genes (fnbA and fnbB) revealed that 100% of the isolates carried hla, 77.7% had hlb and 88.8 % had fnbA. On the other hand, only 38.8% of the isolates harbored fnbB. This research found various drug resistance in S.haemolyticus, as well as the high prevalence of the virulence genes hla, hlb and fnbA. [ABSTRACT FROM AUTHOR]

Staphylococcus haemolyticus (S. haemolyticus) is the second most commonly isolated coagulase-negative staphylococcus (CoNS) in patients with hospital-acquired infections. It can produce phenol-soluble modulin (PSM) toxins and form biofilms. Compared with the wealth of information on Staphylococcus aureus and Staphylococcus epidermidis , very little is known about S. haemolyticus. There is an urgent need to find an effective preparation to combat the harm caused by S. haemolyticus infection. Chinese herbs have been utilized to cure inflammation and infectious diseases and have a long history of anticancer function in China. Here, we modified fusaric acid characterized from the metabolites of Gibberella intermedia , an endophyte previously isolated from Polygonum capitatum. This study shows that fusaric acid analogs (qy17 and qy20) have strong antibacterial activity against S. haemolyticus. In addition, crystal violet analyses and scanning electron microscopy observations demonstrated that qy17 inhibited biofilm formation and disrupted mature biofilms of S. haemolyticus in a dose-dependent manner. Additionally, it reduced the number of live bacteria inside the biofilm. Furthermore, the antibiofilm function of qy17 was achieved by downregulating transcription factors (sigB), transpeptidase genes (srtA), and bacterial surface proteins (ebp , fbp) and upregulating biofilm-related genes and the density-sensing system (agrB). To further elucidate the bacteriostatic mechanism, transcriptomic analysis was carried out. The following antibacterial mechanisms were uncovered: (i) the inhibition of heat shock (clpB , groES , groL , grpE , dnaK , dnaJ)-, oxidative stress (aphC)- and biotin response (bioB)-related gene expression, which resulted in S. haemolyticus being unable to compensate for various stress conditions, thereby affecting bacterial growth; and (ii) a reduction in the expression of PSM-beta (PSMβ1, PSMβ2, PSMβ3) toxin- and Clp protease (clpP , clpX)-related genes. These findings could have major implications for the treatment of diseases caused by S. haemolyticus infections. Our research reveals for the first time that fusaric acid derivatives inhibit the expression of biofilm formation-related effector and virulence genes of S. haemolyticus. These findings provide new potential drug candidates for hospital-acquired infections caused by S. haemolyticus. [ABSTRACT FROM AUTHOR]

Introduction: Sepsis is a systemic infection that causes multiorgan failure and death. The death rate that is caused by sepsis is increasing. This high value of death has a correlation with the resistance of antibiotics. However, increased antibiotic resistance is not balanced with new research about antibiotics. As a consequence, it causes difficulties in handling sepsis patients who need antibiotic 1-2 hours after diagnosis is enforced. Methods: This was a descriptive study with case study design to analyze medical records of the patients, evaluating the pattern of bacterial resistance to antibiotic in 221 patients with sepsis with 240 blood isolates to identify. Results: From 221 patients identified as sepsis, there were 97 male patients (43.9%) and 124 female patients (56.1%), mostly between 18-59 years old (63.8%), with the highest level in female (54.8 %) and elderly (66.3%). The bacteria that caused the most sepsis were gram-positive. The most species in gram-positive are Staphylococcus haemolyticus (16.3%) and Staphylococcus aureus (12.5%), and the most species in gram-negative is Escheriichia coli (13.3%). The most sensitive antibiotics in gram-positive bacteria were Piperacillin-Tazobactam (100%), Daptomycin (99.2%), and Clindamycin (99.2%). The sensitive antibiotics in gram-negative bacteria were Amikacin (85.9%), Cefoperazone (84.6%), and Piperacillin-Tazobactam (84.1%). Conclusion: The most sensitive antibiotics in gram-positive bacteria were Piperacillin-Tazobactam, Daptomycin, and Clindamycin. The sensitive antibitics in gram-negative bacteria were Amikacin, Cefoperazone, and Piperacillin-Tazobactam.

Staphylococcus haemolyticus (S. haemolyticus) is one of the Coagulase-negative staphylococci (CoNS) that inhabits the skin as a commensal. It is increasingly implicated in opportunistic infections, including diabetic foot ulcer (DFU) infections. In contrast to the abundance of information available for S. aureus and S. epidermidis, little is known about the pathogenicity of S. haemolyticus, despite the increased prevalence of this pathogen in hospitalized patients. We described, for the first time, the pathogenesis of different clinical isolates of S. haemolyticus isolated from DFU on primary human skin fibroblast (PHSF) cells. Virulence-related genes were investigated, adhesion and invasion assays were carried out using Giemsa stain, transmission electron microscopy (TEM), MTT and flowcytometry assays. Our results showed that most S. haemolyticus carried different sets of virulence-related genes. S. haemolyticus adhered to the PHSF cells to variable degrees. TEM showed that the bacteria were engulfed in a zipper-like mechanism into a vacuole inside the cell. Bacterial internalization was confirmed using flowcytometry and achieved high intracellular levels. PHSF cells infected with S.haemolyticus suffered from amarked decrease in viability and increased apoptosis when treated with whole bacterial suspensions or cell-free supernatants but not with heat-treated cells. After co-culture with PBMCs, S. haemolyticus induced high levels of pro-inflammatory cytokines. This study highlights the significant development of S. haemolyticus, which was previously considered a contaminant when detected in cultures of clinical samples. Their high ability to adhere, invade and kill the PHSF cells illustrate the severe damage associated with DFU infections. Abbreviations CoNS, coagulase-negative staphylococci; DFU, diabetic foot ulcer; DM, diabetes mellitus; DMEM, Dulbecco’s Modified Eagle Medium; MTT, 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide; PBMCs,peripheral blood mononuclear cells; PHSF, primary human skin fibroblast; CFU, colony-forming unit.

Staphylococcus haemolyticus (S. haemolyticus) is the second most commonly isolated coagulase-negative staphylococcus (CoNS) in patients with hospital-acquired infections. It can produce phenol-soluble modulin (PSM) toxins and form biofilms. Compared with the wealth of information on Staphylococcus aureus and Staphylococcus epidermidis, very little is known about S. haemolyticus. There is an urgent need to find an effective preparation to combat the harm caused by S. haemolyticus infection. Chinese herbs have been utilized to cure inflammation and infectious diseases and have a long history of anticancer function in China. Here, we modified fusaric acid characterized from the metabolites of Gibberella intermedia, an endophyte previously isolated from Polygonum capitatum. This study shows that fusaric acid analogs (qy17 and qy20) have strong antibacterial activity against S. haemolyticus. In addition, crystal violet analyses and scanning electron microscopy observations demonstrated that qy17 inhibited biofilm formation and disrupted mature biofilms of S. haemolyticus in a dose-dependent manner. Additionally, it reduced the number of live bacteria inside the biofilm. Furthermore, the antibiofilm function of qy17 was achieved by downregulating transcription factors (sigB), transpeptidase genes (srtA), and bacterial surface proteins (ebp, fbp) and upregulating biofilm-related genes and the density-sensing system (agrB). To further elucidate the bacteriostatic mechanism, transcriptomic analysis was carried out. The following antibacterial mechanisms were uncovered: (i) the inhibition of heat shock (clpB, groES, groL, grpE, dnaK, dnaJ)-, oxidative stress (aphC)- and biotin response (bioB)-related gene expression, which resulted in S. haemolyticus being unable to compensate for various stress conditions, thereby affecting bacterial growth; and (ii) a reduction in the expression of PSM-beta (PSMβ1, PSMβ2, PSMβ3) toxin- and Clp protease (clpP, clpX)-related genes. These findings could have major implications for the treatment of diseases caused by S. haemolyticus infections. Our research reveals for the first time that fusaric acid derivatives inhibit the expression of biofilm formation-related effector and virulence genes of S. haemolyticus. These findings provide new potential drug candidates for hospital-acquired infections caused by S. haemolyticus.

An emergence of multidrug-resistant (MDR) Staphylococcus haemolyticus has been observed in the neonatal intensive care unit (NICU) of Nîmes University Hospital in southern France. A case-control analysis was conducted on 96 neonates, to identify risk factors associated with S. haemolyticus infection, focusing on clinical outcomes. Forty-eight MDR S. haemolyticus strains, isolated from neonates between October 2019 and July 2022, were investigated using routine in vitro procedures and whole-genome sequencing. Additionally, five S. haemolyticus isolates from adult patients were sequenced to identify clusters circulating within the hospital environment. The incidence of neonatal S. haemolyticus was significantly associated with low birth weight, lower gestational age, and central catheter use ( p  < 0.001). Sepsis was the most frequent clinical manifestation in this series (20/46, 43.5%) and was associated with five deaths. Based on whole-genome analysis, three S. haemolyticus genotypes were predicted: ST1 (6/53, 11%), ST25 (3/53, 5.7%), and ST29 (44/53, 83%), which included the subcluster II-A, predominantly emerging in the neonatal department. All strains were profiled in silico to be resistant to methicillin, erythromycin, aminoglycosides, and fluoroquinolones, consistent with in vitro antibiotic susceptibility tests. Moreover, in silico prediction of biofilm formation and virulence-encoding genes supported the association of ST29 with severe clinical outcomes, while the persistence in the NICU could be explained by the presence of antiseptic and heavy metal resistance-encoding genes. The clonality of S. haemolyticus ST29 subcluster II-A isolates confirms healthcare transmission causing severe infections. Based on these results, reinforced hygiene measures are necessary to eradicate the nosocomial transmission of MDR strains.

Introduction:Staphylococcus haemolyticus is an acquired opportunistic pathogen causing nosocomial infections. Our previous studies of S. haemolyticus showed a group of isolates that produced a significantly higher disease severity than the others. Further molecular typing showed that the sequence type (ST) 42 was the major clone among the isolates. The main aim of this study was to characterize ST42. Materials and Methods: Sixty-one and 36 isolates were collected from burn and nonburn patients, respectively. Molecular typing, antibiotic susceptibility assays, and phenotypic characterizations were performed. Results: Thirteen STs, including seven new STs, were established (ST42 to ST48). ST42 was prevalent in burn and nonburn patients, and all the pulsotype C isolates were ST42. Four of the novel STs originated from ST3, suggesting that these clonal lineages evolved locally. ST3 and ST42 showed a significant difference in clindamycin susceptibility; molecular typing showed only one MLST locus variation among seven loci in SH1431, which has been reportedly involved in the regulation of biofilm formation through Zn 2+ binding affinities. Conclusions: Seven novel S. haemolyticus STs were identified; phylogenetic analysis suggested the presence of locally evolved clonal lineages. The predominant ST42 showed weak biofilm formation abilities; other factors that cause the clonal lineage change still need further investigation. [ABSTRACT FROM AUTHOR]

Staphylococci are the most common pathogens isolated from skin infections in livestock or companion animals. Antibiotic therapy is the best treatment for infections, but local or systemic use of antimicrobials increases the risk of bacterial resistance. Insects are rich in antimicrobial peptides, which can reduce bacterial resistance and can be used to treat bacterial infections after skin burns. We propose that the use of the darkling beetle (Z. morio) hemolymph to treat skin infections in mice by Staphylococcus haemolyticus is one of the alternatives. Z. morio hemolymph alleviated the increase in wound area temperature in mice with a skin infection, reduced the bacterial load of the wound, and accelerated the wound healing speed significantly. Pathological sections showed that Z. morio hemolymph can significantly reduce inflammatory cell infiltration, and promote skin tissue repair. Real-time fluorescent quantitative polymerase chain reaction (PCR) revealed that the Z. morio hemolymph can significantly reduce the levels of pro-inflammatory cytokines, including interleukin-1 beta (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and chemokine interleukin-8 (IL-8). Our findings suggest that Z. morio antibacterial hemolymph can promote wound contraction, relieve local inflammatory responses and promote wound healing in mice infected with a heat injury, which has a positive therapeutic effect and enormous potential for skin thermal injury. [ABSTRACT FROM AUTHOR]

Coagulase Negative Staphylococci (CONS) have in the current years been increasingly incriminated as important pathogens. CONS are frequently implicated in various nosocomial infections, particularly blood stream infections and prosthetic infections. The present study was carried out to study the Coagulase Negative Staphylococci isolated from various clinical specimens and to determine their antimicrobial susceptibility patterns. A total of 60 strains of CONS isolated in pure form or isolated twice from various clinical specimens were recruited for the study. All clinical specimens were processed as per the standard laboratory methods. Out of 83 culture positive specimens CONS spp. were isolated in 60 specimens. In the present study maximum isolates i.e 20% isolates were recovered from paediatric ward patients, followed by 18.3% isolates being isolated from patients admitted in ICU. Isolation of CONS was maximum from blood (45%), followed by pus (21.6%) and urine (20%). Predominance of Staphylococcus haemolyticus (25%) and Staphylococcus warneri (20%) was seen. Maximum resistance was seen for ampicillin (80%), followed by resistance for ciprofloxacin (74.3%), erythromycin (73.3%) and the minimum resistance was seen for tigecycline (5%). Methicillin resistant CONS isolates (MRCONS) were seen maximum in blood (p

Staphylococcus aureus and Staphylococcus haemolyticus are common members of the human microbiota, but they are also opportunistic pathogens. To identify antibiotic resistance in healthy individuals, we present the genome sequences of S. aureus 139 N-1 and S. haemolyticus 173 N-3, both isolated from nasal swab samples from asymptomatic female participants., Competing Interests: The authors declare no conflict of interest.

Background: For years, coagulase-negative staphylococci (CoNS) were not considered a cause of bloodstream infections (BSIs) and were often regarded as contamination. However, the association of CoNS with nosocomial infections is increasingly recognized. The identification of more than 40 different CoNS species has been driven by the introduction of matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Yet, treatment guidelines consider CoNS as a whole group, despite increasing antibiotic resistance (ABR) in CoNS. This retrospective study provides an in-depth data analysis of CoNS isolates found in human blood culture isolates between 2013 and 2019 in the entire region of the Northern Netherlands. Methods: In total, 10,796 patients were included that were hospitalized in one of the 15 hospitals in the region, leading to 14,992 CoNS isolates for (ABR) data analysis. CoNS accounted for 27.6% of all available 71,632 blood culture isolates. EUCAST Expert rules were applied to correct for errors in antibiotic test results. Results: A total of 27 different CoNS species were found. Major differences were observed in occurrence and ABR profiles. The top five species covered 97.1% of all included isolates: S. epidermidis, S. hominis, S. capitis, S. haemolyticus, and S. warneri. Regarding ABR, methicillin resistance was most frequently detected in S. haemolyticus (72%), S. cohnii (65%), and S. epidermidis (62%). S. epidermidis and S. haemolyticus showed 50–80% resistance to teicoplanin and macrolides while resistance to these agents remained lower than 10% in most other CoNS species. Conclusion: These differences are often neglected in national guideline development, prompting a focus on ‘ABR-safe’ agents such as glycopeptides. In conclusion, this multi-year, full-region approach to extensively assess the trends in both the occurrence and phenotypic resistance of CoNS species could be used for evaluating treatment policies and understanding more about these important but still too often neglected pathogens.

One hundred bacteria isolated from conjunctivitis and keratitis showed 14 different bacterial species as Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa were the most. All 100 isolates were tested for their ability to form biofilm, 65 isolates (65%) showed positive for congo red agar (CRA) test with the exception of Enterobacter hormaechei, Staphylococcus haemolyticus and Bacillus pumilus species, while 84 isolates (84%) showed positive for microtiter plate assay except Bacillus pumilus species. Nevertheless, icaAD genes were detected in 75 isolates (75%) within all species. Although 100 bacterial isolates showed different results toward biofilm production tests, CRA, MTP assay and icaAD genes, but there was no significant difference found among these tests. Appliedally, the ability to adhere on contact lenses (In vitro) appeared Staphylococcus aureus has the highest adhesion 12(92.3%) followed by P. aeruginosa 3(75%) and Staphylococcus epidermidis 3(60%). [ABSTRACT FROM AUTHOR]

We report in this study for the first time the prevalence of multiple resistant Staphylococcus haemolyticus in clinical settings in Saudi Arabia. A total of 1060 clinical specimens of hospitalized patients were screened for the presence of S. haemolyticus in the period between September and December 2020. Primary identification of the isolates was carried out by colonial characteristics on mannitol salt agar and clumping factor test, confirmation of presumptive isolates and antimicrobial susceptibility testing was performed by Vitek® 2, while PCR was employed to detect mecA and vanA genes. A total of 20 S. haemolyticus isolates were recovered from 20 samples (blood cultures, urine, nasal swab, wound swab, groin swab, and axilla swab), 90% (P <0.001, x2) of the isolates were multiple resistant to three antimicrobial agents and more. Resistance to oxacillin was exhibited in 95% of the isolates, while none of the isolates were resistant to vancomycin and linezolid, yet resistance to rifampicin was observed in 30 % of the isolates. The findings of this study highlights the emerging trends of Staphylococcus haemolyticus as potential drug resistant pathogen in hospital settings in Saudi Arabia, which requires in depth investigation on molecular understanding on antimicrobial resistance and virulence traits of the strains. [ABSTRACT FROM AUTHOR]

The rapid intensification of tilapia aquaculture is associated with losses due to emerging pathogens. The gastrointestinal microbiota plays a vital role in the host's health by modulating the immune system and several physiological functions. Recent studies suggest that bacterial pathogens may deleteriously affect the microbiota structure. This study analyzed the effect of challenging tilapia with two emerging bacterial pathogens: Staphylococcus haemolyticus and Providencia vermicola, on the stomach and intestinal microbiota. Immediately after infection, fish started showing disease signs, tilapia infected with S. haemolyticus and P. vermicola registered 40 and 67% survival after seven days, while no mortality was reported in the control group during the trial. Amplicon libraries constructed by amplifying the V4 region of the 16S rRNA gene were analyzed. Proteobacteria was the most dominant phylum in the stomach and intestine of all infection groups. Staphylococcus haemolyticus infection disrupted both stomach and intestine microbiota. For instance, Bacteroidetes abundance increased while Proteobacteria dropped in the stomach of fish infected with S. haemolyticus. Both alpha and beta diversity indexes showed a clear differentiation of this group from the control and P. vermicola- infected fish. The microbiota of the stomach and intestine of this last group was also affected, although the effects were not as severe as in the case of the S. haemolyticus challenge. Results revealed that both emerging pathogens could lead to dysbiosis, affecting the functioning of the tilapia gut microbiota. • Staphylococcus haemolyticus and Providencia vermicola infected tilapia, causing 33 and 60% mortality, accompanied by disease signs. • Both pathogens affected the stomach and intestine microbiota, but S. haemolyticus severely disrupted the taxonomic structure. • S. haemolyticus infection caused loss of Deinococcus Thermus and an increase of Bacteroidetes and Fusobacteria in the stomach. • The intestine of tilapia was dominated by Proteobacteria, but a decrease was reported in S. haemolyticus -infected group. • Both tissues showed dysbiosis signs after the infection with S. haemolyticus and P. vermicola. [ABSTRACT FROM AUTHOR]