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Abstract Background A major worldwide health issue is the rising frequency of resistance of bacteria.Drug combinations are a winning strategy in fighting resistant bacteria and might help in protecting the existing drugs.Monolaurin is natural compound extracted from coconut oil and has a promising antimicrobial activity against Staphylococcus.aureus. This study aims to examine the efficacy of monolaurin both individually and in combination with β-lactam antibiotics against Staphylococcus aureus isolates. Methods Agar dilution method was used for determination of minimum inhibitory concentration (MIC) of monolaurin against S.aureus isolates. Scanning electron microscope (SEM) was used to detect morphological changes in S.aureus after treatment with monolaurin. Conventional and Real-time Polymerase chain reaction (RT-PCR) were performed to detect of beta-lactamase (blaZ) gene and its expressional levels after monolaurin treatment. Combination therapy of monolaurin and antibiotics was assessed through fractional inhibitory concentration and time-kill method. Results The antibacterial activity of monolaurin was assessed on 115 S.aureus isolates, the MIC of monolaurin were 250 to 2000 µg/ml. SEM showed cell elongation and swelling in the outer membrane of S.aureus in the prescence of 1xMIC of monolaurin. blaZ gene was found in 73.9% of S.aureus isolates. RT-PCR shows a significant decrease in of blaZ gene expression at 250 and 500 µg/ml of monolaurin. Synergistic effects were detected through FIC method and time killing curve. Combination therapy established a significant reduction on the MIC value. The collective findings from the antibiotic combinations with monolaurin indicated synergism rates ranging from 83.3% to 100%.In time-kill studies, combination of monolaurin and β-lactam antibiotics produced a synergistic effect. Conclusion This study showed that monolaurin may be a natural antibacterial agent against S. aureus, and may be an outstanding modulator of β-lactam drugs. The concurrent application of monolaurin and β-lactam antibiotics, exhibiting synergistic effects against S. aureus in vitro, holds promise as potential candidates for the development of combination therapies that target particularly, patients with bacterial infections that are nearly incurable.

Background: A major worldwide health issue is the rising frequency of resistance of bacteria.Drug combinations are a winning strategy in fighting resistant bacteria and might help in protecting the existing drugs.Monolaurin is natural compound extracted from coconut oil and has a promising antimicrobial activity against Staphylococcus.aureus. This study aims to examine the efficacy of monolaurin both individually and in combination with β-lactam antibiotics against Staphylococcus aureus isolates. Methods: Agar dilution method was used for determination of minimum inhibitory concentration (MIC) of monolaurin against S.aureus isolates. Scanning electron microscope (SEM) was used to detect morphological changes in S.aureus after treatment with monolaurin. Conventional and Real-time Polymerase chain reaction (RT-PCR) were performed to detect of beta-lactamase (blaZ) gene and its expressional levels after monolaurin treatment. Combination therapy of monolaurin and antibiotics was assessed through fractional inhibitory concentration and time-kill method. Results: The antibacterial activity of monolaurin was assessed on 115 S.aureus isolates, the MIC of monolaurin were 250 to 2000 µg/ml. SEM showed cell elongation and swelling in the outer membrane of S.aureus in the prescence of 1xMIC of monolaurin. blaZ gene was found in 73.9% of S.aureus isolates. RT-PCR shows a significant decrease in of blaZ gene expression at 250 and 500 µg/ml of monolaurin. Synergistic effects were detected through FIC method and time killing curve. Combination therapy established a significant reduction on the MIC value. The collective findings from the antibiotic combinations with monolaurin indicated synergism rates ranging from 83.3% to 100%.In time-kill studies, combination of monolaurin and β-lactam antibiotics produced a synergistic effect. Conclusion: This study showed that monolaurin may be a natural antibacterial agent against S. aureus, and may be an outstanding modulator of β-lactam drugs. The concurrent application of monolaurin and β-lactam antibiotics, exhibiting synergistic effects against S. aureus in vitro, holds promise as potential candidates for the development of combination therapies that target particularly, patients with bacterial infections that are nearly incurable. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance in Staphylococcus spp. colonising the nasopharynx can create risk factors of therapeutic treatment failure or prophylaxis in pregnant women. Resistance is mostly encoded on plasmids (e.g., blaZ gene for penicillinase synthesis) or chromosomes (e.g., mecA and mecC for methicillin resistance). The mecA gene is part of the chromosomal mec gene cassette (SCCmec), which is also located on the plasmid. The disc diffusion method for the selected drugs (beta-lactams, fluoroquinolones, streptogramins, aminoglicosides, macrolides, oxasolidinones, tetracyclines and other groups) was used. PCR for blaZ, mecA and mecC genes and SCCmec cassette detection and typing were performed. S. aureus (54.4%) and S. epidermidis (27.9%) were the most prevalent and showed the highest diversity of resistance profiles. The blaZ, mecA and mecC genes were reported in 95.6%, 20.6% and 1.5% of isolates, respectively. The highest resistance was found to beta-lactams, commonly used during pregnancy. Resistance to a variety of antimicrobials, including benzylpenicillin resistance in blaZ-positive isolates, and the existence of a very high diversity of SCCmec cassette structures in all staphylococci selected from the nasopharyngeal microbiota of pregnant women were observed for the first time. Knowledge of the prevalence of antimicrobial-resistant staphylococci in the nasopharynx of pregnant women may be important for the appropriate treatment or prophylaxis of this group of patients. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance in Staphylococcus spp. colonising the nasopharynx can create risk factors of therapeutic treatment failure or prophylaxis in pregnant women. Resistance is mostly encoded on plasmids (e.g., blaZ gene for penicillinase synthesis) or chromosomes (e.g., mecA and mecC for methicillin resistance). The mecA gene is part of the chromosomal mec gene cassette (SCCmec), which is also located on the plasmid. The disc diffusion method for the selected drugs (beta-lactams, fluoroquinolones, streptogramins, aminoglicosides, macrolides, oxasolidinones, tetracyclines and other groups) was used. PCR for blaZ, mecA and mecC genes and SCCmec cassette detection and typing were performed. S. aureus (54.4%) and S. epidermidis (27.9%) were the most prevalent and showed the highest diversity of resistance profiles. The blaZ, mecA and mecC genes were reported in 95.6%, 20.6% and 1.5% of isolates, respectively. The highest resistance was found to beta-lactams, commonly used during pregnancy. Resistance to a variety of antimicrobials, including benzylpenicillin resistance in blaZ-positive isolates, and the existence of a very high diversity of SCCmec cassette structures in all staphylococci selected from the nasopharyngeal microbiota of pregnant women were observed for the first time. Knowledge of the prevalence of antimicrobial-resistant staphylococci in the nasopharynx of pregnant women may be important for the appropriate treatment or prophylaxis of this group of patients.

The study was conducted to compare phenotypic and genotypic methods of detection of two beta-lactam resistant genes in Staphylococcus aureus isolates from mastitic milk. Nine (9/92) S. aureus isolates were revived and used. The isolates were subjected to phenotypic prediction of blaZ gene using the penicillin disk diffusion method and nitrocefin test while prediction of mecA gene was observed using the cefoxitin disk diffusion method. Both the penicillin disk diffusion method and nitrocefin test detected three (33.33%) isolates to be producing beta-lactamase while PCR detected two (22.22%) isolates positive for blaZ gene. Kappa coefficient revealed perfect agreement (1.00) between phenotypic methods and substantial agreement (0.7270) between the phenotypic methods and PCR. In the detection of mecA-mediated methicillin resistance, none of the isolates resulted positive for mecA gene for both tests hence, no methicillin-resistant S. aureus (MRSA) was detected. The results of the study show that there are S. aureus isolates from mastitic milk that expresses beta-lactam resistance through beta-lactamase production however, while there was no MRSA detected, the study highly suggests the monitoring of the antimicrobial usage in the farms and their management practices to avoid further development of resistance and possible transfer of resistance from animals to humans and/or humans to animals. [ABSTRACT FROM AUTHOR]

Background and Objective: Staphylococcus aureus (S. aureus) is the most common cause of nosocomial infections. Treatment of Staphylococcal infections has become more complicated due to the emergence of methicillin-resistant S.aureus (MRSA) strains. This study was done to determine the frequency of methicillin resistance encoding gene (mecA) and β-lactamase resistance encoding gene (blaZ) in S. aureus isolates from clinical samples using Polymerase Chain Reaction (PCR) method. Methods: This descriptive-analytic study was carried out on 59 S. aureus isolates from clinical samples in Gorgan hospitals from January-February 2017 to June-July 2017. All the isolates were identified using gram staining, catalase test, tube coagulase test, growth on Mannitol salt agar medium and the DNase test in the Microbiology Laboratory .Antibiotic resistance was evaluated using the standard disk diffusion. Iodometric method was used to detect β-lactamase production / activity in this bacterium. PCR test was done to detect mecA and blaZ genes. Results: All S. aureus isolates (100%) clinical samples possessed blaZ gene, followed by 27 isolates (45.8%) possessed mecA gene (MRSA), which these isolates possessed mecA gene were concurrently positive for blaZ gene. 5% of oxacillin-resistant strains and 3% of cefoxitin-resistant strains possessed mecA gene and 47 isolates (79.4%) carrying blaZ gene were β-lactamase-positive in phenotypic method. Conclusion: This study showed that in all clinical samples isolated S. aureus isolates which these isolates possessed mecA gene were concurrently positive for blaZ gene.

Isolates of staphylococci were collected from fresh beef and checked for the susceptibility to various classes of antibiotics. The existence of genes concerned in resistance to beta-lactams (mecA, blaZ) conferring resistance to Oxacillin, Penicillin was investigated in the three staphylococcal isolates resistance to all antibiotic used in this study (Staphylococcus aureus, Staphylococcus sciuri and Staphylococcus epidermidis) by polymerase chain reaction (PCR). The results indicate contamination of fresh meat samples with Staphylococci species and the Staphylococcus count of fresh meat samples was found to range from 4.39 × 10³ – 8.63 × 10³ (included 21 (47.72%) isolates of S. aureus and 23 (52.27%) isolates of CoNS from a total of 44 (88%) isolates of Staphylococci was obtained from the fresh beef samples). From the results of the antibiotic susceptibility test, the highest resistance was noticed against Amoxicillin, Ampicillin and Oxacillin. An association of Amoxicillin + Clavulanic acid and Ampicillin + Sulbactam were the most active antibiotics and it was also detected one isolate of S. aureus and two isolates of CoNS were resistance to all antimicrobial classes. The blaZ gene (concerned in beta-lactam resistance) and mecA gene (concerned in methicillin resistance) was detected in all three resistant staphylococcal isolates, that indicating this agent is wide prevalence between the CoNS, also. The results indicate the fresh beef and other types of meat may be deemed reservoirs of bacteria harboring genes possibility participate in the development of staphylococcal antibiotic resistance. [ABSTRACT FROM AUTHOR]

The study described in this Research Communication investigated the genotypic and phenotypic profiles of resistance to beta-lactams and other antimicrobials in non-aureus Staphylococci (NAS) isolated from buffalo, goat and sheep mastitis in the Northeast region of Brazil. A total of 190 isolates were analyzed and 42.3, 43.9 and 23.6% of them were positive for blaZ gene in buffalo, goat and sheep, respectively. Regarding the animal groups, in goats, amoxicillin was the antimicrobial with highest resistance index (72.7%), followed by penicillin G in buffaloes (51.9%) and ampicillin in sheep (43.1%). With regard to multiple antimicrobial resistance, 30.8% of NAS isolates from buffalo milk samples, 25.8% from goats and 25.0% from sheep presented multidrug-resistance. In the minimum inhibitory concentration (MIC) technique, amoxicillin MIC50 and MIC90 were 64 and 128 μg/ml, respectively, among isolates of the three animal species. In conclusion, high rates of resistance to beta-lactams are presented among NAS isolated from mastitis cases in buffaloes, goats and sheep in Northeast region of Brazil. These results provide an alert to animal and human health researchers, suggesting that the frequency of NAS needs to be reduced because they carry resistance genes which might increase the existing levels of antimicrobial resistance. [ABSTRACT FROM AUTHOR]

Background and Objective: Staphylococcus aureus (S. aureus) is the most common cause of nosocomial infections. Treatment of Staphylococcal infections has become more complicated due to the emergence of methicillin-resistant S.aureus (MRSA) strains. This study was done to determine the frequency of methicillin resistance encoding gene (mecA) and β-lactamase resistance encoding gene (blaZ) in S. aureus isolates from clinical samples using Polymerase Chain Reaction (PCR) method. Methods: This descriptive-analytic study was carried out on 59 S. aureus isolates from clinical samples in Gorgan hospitals from January-February 2017 to June-July 2017. All the isolates were identified using gram staining, catalase test, tube coagulase test, growth on Mannitol salt agar medium and the DNase test in the Microbiology Laboratory .Antibiotic resistance was evaluated using the standard disk diffusion. Iodometric method was used to detect β-lactamase production / activity in this bacterium. PCR test was done to detect mecA and blaZ genes. Results: All S. aureus isolates (100%) clinical samples possessed blaZ gene, followed by 27 isolates (45.8%) possessed mecA gene (MRSA), which these isolates possessed mecA gene were concurrently positive for blaZ gene. 5% of oxacillin-resistant strains and 3% of cefoxitin-resistant strains possessed mecA gene and 47 isolates (79.4%) carrying blaZ gene were β-lactamase-positive in phenotypic method. Conclusion: This study showed that in all clinical samples isolated S. aureus isolates which these isolates possessed mecA gene were concurrently positive for blaZ gene. [ABSTRACT FROM AUTHOR]

Reports of β-lactam-resistant Staphylococcus aureus in artisanal goat cheese are increasing, and this phenomenon is relevant to public health. The objective of the present study was to determine the prevalence of S. aureus strains carrying the blaZ and mecA resistance genes, as well as the genes encoding the staphylococcal enterotoxins SEA, SEB, SEC, SED, SEE, and TSST-1 in artisanal coalho cheese made from goat milk produced in northeastern Brazil. We used biochemical and molecular tests to characterize 54 S. aureus isolates found in artisanal coalho cheese collected from commercial establishments producing animal products in 11 municipalities of Pernambuco State, Brazil. A PCR analysis revealed that 42.6% (23/54) of the isolates were positive for the blaZ gene, and 7.4% (4/54) were resistant to methicillin by phenotypic testing. We did not detect mecA or any genes encoding enterotoxins. The presence of S. aureus carriers of the blaZ gene and the identification of methicillin-resistant S. aureus strains are of concern for the health of consumers of this type of cheese. [ABSTRACT FROM AUTHOR]

Food intoxication by S.aureus was listed as the third etiology of food intoxication all over the world. This study was conducted to investigate the prevalence rate of S.aureus in skim milk soft cheese (Kariesh cheese) and ice cream samples from local markets in Menoufia province, Egypt. Two-hundred samples (100 for each) were examined bacteriologically for prevalence of Staphylococcus aureus through culturing on specific media and biochemical identification. In addition to the molecular characterization of some virulence and antibiotic resistance genes in isolated strains. The obtained results revealed that the prevalence rate of S. aureus was 24% in kariesh cheese with an average count of 1.22x 103 ±1.39 x 102 CFU/g and 16% in ice-cream samples with an average count of 1.04 x103 ± 8.89x10 CFU/ml .Furthermore, the molecular characterization using specific primers sets for detection of Coa, Spa and blaZ genes of S. aureus was performed by amplification of these primers at single amplicon at 630 bp, 226 bp, and 173bp respectively. The molecular results confirmed the detection of these genes in all tested isolates of S.aureus. The obtained results proved that PCR technique is more sensitive and specific in detection of these genes than other conventional techniques and help to understanding the role of these genes in pathogenicity pathway in different disease conditions and construction of effective control measure. [ABSTRACT FROM AUTHOR]

Little is known about the prevalence of β-lactamase production in penicillin-susceptible Staphylococcus aureus isolates under high-susceptibility conditions. We analyzed S. aureus isolates with penicillin G minimum inhibitory concentration (MIC) ≤ 0.12 μg/ml that were recovered from in-/outpatients (n = 108) between 2016 and 2017 in Japan. β-Lactamase production was detected by nitrocefin-based and Clinical and Laboratory Standards Institute penicillin zone edge testing and blaZ PCR. All isolates were categorized as having penicillin G MIC ≤0.03 μg/ml using an automated system; MICs determined based on the microdilution method were 0.016 μg/ml (2%), 0.03 μg/ml (44%), and 0.06 μg/ml (54%). Notably, no isolates harbored the blaZ gene. The results from the nitrocefin-based and zone edge tests were consistent with those obtained by PCR. S. aureus isolates with penicillin G MIC ≤0.03 μg/ml exhibited a low frequency of β-lactamase production. Thus, screening for β-lactamase production may be unnecessary for isolates showing such high susceptibility. [ABSTRACT FROM AUTHOR]

Introduction: Bovine mastitis is a frequent cause of economic loss in dairy herds. Coagulase-negative staphylococci (CoNS) are increasing in importance as cause of bovine intramammary infection throughout the world in recent years. CoNS have been isolated from milk samples collected from cows with clinical and subclinical mastitis in several countries. Identification of mastitis pathogens is important when selecting appropriate antimicrobial therapy. Methodology: A total of 93 strains of Staphylococcus spp isolated from bovine mastitis in Argentina between 2010 and 2013 were identified by PCR-restriction fragment length polymorphism (PCR-RFLP) using the gap gene and were tested for the presence of blaZ and mecA genes by PCR and for the susceptibility to penicillin and cefoxitin by disk diffusion. Results: The most common CoNS species was S. chromogenes 46.2% (43/93), followed by S. devriesei 11.8% (11/93) and S. haemolyticus 9.7% (9/93). The blaZ gene was detected in 19 (20.4%), but only 16 (17.2%) isolates were resistant to penicillin; the mecA was detected in 6 (6.5%) isolates but only 4 (4.3) were resistant to cefoxitin. The 6 mecA-positive isolates showed oxacillin MICs ≥ 0.5 µg/ml. Discussion: CoNS are important minor mastitis pathogens and can be the cause of substantial economic losses. The presence of methicillin resistant isolates emphasizes the importance of identification of CoNS when an intramammary infection is present because of the potential risk of lateral transfer of resistant genes among staphylococcal species. [ABSTRACT FROM AUTHOR]

This study determined the prevalence of Staphylococcus aureus in food of animal origin, investigated its antimicrobial susceptibility profiles and antimicrobial-resistant genes encoding resistance to methicillin (mecA), penicillin (blaZ), and vancomycin (vanA). Two hundred and sixty food samples, including raw retail milk, meat, and meat products, were obtained from local retail shops in Mansoura city, Egypt. The overall prevalence of S. aureus in the total examined food samples was 32.69% (85/260). Methicillin-resistant S. aureus (MRSA) was identified in 11.15% (29/260) of the tested food samples. S. aureus indicated a high resistance to nalidixic acid, penicillin, ampicillin, cefuroxime, trimethoprim/sulfamethoxazole, and azithromycin. The multiple antibiotic resistance (MAR) rate was 89.4% of the total S. aureus isolates, and MARindex ranges from 0.05-0.64. Genotypically, mecA and blaZ genes were identified in a percentage of 34.11% and 82.35%, respectively, while no isolates harbored the vanA gene. The presence of MAR S. aureus particularly, MRSA in food samples, is of great concern and represents a possible threat to the community. Therefore, the study's findings highlight the importance of establishing vigilant food safety practices for food handlers to inhibit the transmission of S. aureus through the food chain to reduce public health risks.

<b>Background and Objective:</b> Detection of methicillin-resistant<i> S. aureus</i> have become a challenge in the presence of oxacillin-susceptible and <i>mecA</i>-positive <i>S. aureus </i>(OS-MRSA), concerning the misidentification events and therapeutic implications. This study aims to identify the OS-MRSA in clinical isolates of Post-viral acute rhinosinusitis, which, hopefully, can interfere with the therapeutic strategy. <b>Materials and Methods:</b> There were 60 patients diagnosed with Post-viral acute rhinosinusitis, recruited from an Ear, Nose and Throat (ENT) outpatient clinic. <i>Staphylococcus aureus</i> isolates were identified from the culture and were then tested for antibiotics susceptibility using a Kirby-Bauer disc diffusion test. The <i>mecA</i>, <i>mecC</i> and <i>blaZ</i> genes were determined using the Polymerase Chain Reaction (PCR) method. <b>Results:</b> <i>Staphylococcus aureus </i>was identified in 20 of the 60 samples from the patients (33.3%; 95% CI: 21.0-45.6). Of the 20 isolates, 19 isolates (95%) had a positive <i>mecA</i> gene, 19 (95%) had a positive <i>mecC</i> gene and 20 (100.0%) had a positive <i>blaZ </i>gene. The majority of the <i>mecA</i>-positive <i>S. aureus</i> showed an oxacillin-susceptible (85%) and 3 isolates (15.0%) were oxacillin-resistant toward the <i>S. aureus</i>. <b>Conclusion:</b> There was a high proportion of Oxacillin/cefoxitin-Susceptible <i>mecA</i>-positive <i>S. aureus</i> in the study population that indicate phenotypic susceptibility to antibiotics does not always indicate the absence of genes that carry resistant traits, thus allowing misidentification if the only phenotypic examination is carried out.