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The tkt (transketolase) gene is one of the seven gene fragments used in the multilocus sequence typing (MLST) system for Streptococcus agalactiae . We discovered that the tkt_134 allele is derived from a homologous gene (which we designate tktX ) that is not present in all S. agalactiae ; all known strains that contain a match to the tkt_134 allele also contain a gene sequence that is much closer in sequence identity to the other non-tkt_134 alleles (i.e., the canonical tkt gene) in the database. Based on these data, the tkt_134 allele has been removed from the MLST database as of September 2021, and all sequence types containing tkt_134 have also been removed.IMPORTANCEMultilocus sequence typing (MLST) databases are a common good and remain important for research, medical, and epidemiological purposes. This remains true even in the context of widespread whole-genome sequencing. We discovered a contaminating allele of the tkt gene in the S. agalactiae MLST database that led to unstable, ambiguous, or erroneous MLST assignment. The allele has since been removed from the public database based on the results presented in this manuscript., Competing Interests: The authors declare no conflict of interest.

Background: Neonatal sepsis, often attributed to Group B Streptococcus (GBS) infection, poses a critical health risk to infants, demanding rapid and accurate diagnostic approaches. Existing diagnostic approaches are dependent on traditional culture methods, a process that requires substantial time and has the potential to delay crucial therapeutic assessments., Methods: This study introduces an innovative Loop-Mediated Isothermal Amplification (LAMP) assay for the early on-site detection of GBS infection from neonatal sepsis blood samples. To develop a LAMP assay, the primers are designed for the selective targeting of a highly conserved segment within the cfb gene encoding the CAMP factor in Streptococcus agalactiae ensuring high specificity., Results: Rigorous optimization of reaction conditions, including temperature and incubation time, enhances the efficiency of the LAMP assay, enabling rapid and reliable GBS detection within a short timeframe. The diagnostic efficacy of the LAMP assay was evaluated using spiked blood samples by eliminating the DNA extraction step. The simplified colorimetric LAMP assay has the capability to detect S. agalactiae in a neonatal blood sample containing 2 CFU/mL during sepsis. Additionally, the LAMP assay effectively detected S. agalactiae in both the standard and spiked blood samples, with no detectable interference with blood., Conclusion: This optimised LAMP assay emerges as a promising tool for early GBS detection, offering a rapid and accurate on-site solution that has the potential to inform timely interventions and improve outcomes in neonatal sepsis cases., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Group B Streptococcus (GBS) is a leading cause of neonatal meningitis, pneumonia, and sepsis. The biggest contributing factor of neonatal infections is due to vertical transmission from maternal colonisation of GBS in the genitourinary tract. Multiple serotype colonisation is often not investigated in epidemiological studies, but it is an important consideration for serotype-based vaccine development and implementation to ensure less abundant serotypes are not under-represented. In this study, we show that RAPD PCR is a quick tool useful in screening the presence of genetically different strains using multiple colony picks from a single patient swab. We observed a maximum of five different GBS strains colonising a single patient at a specific time., (Crown Copyright © 2021. Published by Elsevier B.V. All rights reserved.)

Group B Streptococcus (GBS) infection in newborns during childbirth can result in death. We described a method to detect GBS from vaginal swabs in pregnant women, without prior enrichment, using real-time polymerase chain reaction (qPCR), and compared its results to the culture method. The qPCR outperforms culture method., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Osteomyelitis is a devastating complication of orthopaedic surgery and commonly caused by Staphylococcus aureus (S. aureus) and Group B Streptococcus (GBS, S. agalactiae). Clinically, S. aureus osteomyelitis is associated with local inflammation, abscesses, aggressive osteolysis, and septic implant loosening. In contrast, S. agalactiae orthopaedic infections generally involve soft tissue, with acute life-threatening vascular spread. While preclinical models that recapitulate the clinical features of S. aureus bone infection have proven useful for research, no animal models of S. agalactiae osteomyelitis exist. Here, we compared the pathology caused by these bacteria in an established murine model of implant-associated osteomyelitis. In vitro scanning electron microscopy and CFU quantification confirmed similar implant inocula for both pathogens (~10 5 CFU/pin). Assessment of mice at 14 days post-infection demonstrated increased S. aureus virulence, as S. agalactiae infected mice had significantly greater body weight, and fewer CFU on the implant and in bone and adjacent soft tissue (p < 0.05). X-ray, µCT, and histologic analyses showed that S. agalactiae induced significantly less osteolysis and implant loosening, and fewer large TRAP + osteoclasts than S. aureus without inducing intraosseous abscess formation. Most notably, transmission electron microscopy revealed that although both bacteria are capable of digesting cortical bone, S. agalactiae have a predilection for colonizing blood vessels embedded within cortical bone while S. aureus primarily colonizes the osteocyte lacuno-canalicular network. This study establishes the first quantitative animal model of S. agalactiae osteomyelitis, and demonstrates a vasculotropic mode of S. agalactiae infection, in contrast to the osteotropic behavior of S. aureus osteomyelitis., (© 2020 Orthopaedic Research Society. Published by Wiley Periodicals LLC.)

Background: Streptococcus agalactiae (Group B Streptococcus, GBS) serotypes, sequence types, and antimicrobial resistance profile vary across different geographic locations affecting disease patterns in newborns. These differences are important considerations for vaccine development efforts and data from large countries in Africa is limited. The aim of this study was to determine serotypes and genotypes of GBS isolates from pregnant women and their newborns in Ethiopia., Methods: A hospital based cross-sectional study was conducted at three hospitals in Ethiopia from June 2014 to September 2015. Out of 225 GBS isolates, 121 GBS were recovered, confirmed and characterized at CDC's Streptococcus Laboratory using conventional microbiology methods and whole genome sequencing., Results: Of the 121 isolates, 87 were from rectovaginal samples of pregnant women, 32 from different body parts of their newborns and 2 from blood of newborns with suspected sepsis. There were 25 mother-infant pairs and 24 pairs had concordant strains. The most prevalent serotypes among mothers and/or their babies were II, Ia and V (41.5, 20.6, 19.5 and 40.6%, 25 and 15.6%, respectively). Multilocus sequence typing (MLST) on 83 isolates showed ST10 (24; 28.9%) and ST2 (12; 14.5%) as most predominant sequence types. All GBS strains were susceptible to penicillin, cefotaxime and vancomycin, which correlated to the presence of wildtype PBP2x types and the lack of known vancomycin-resistance genes. Tetracycline resistance was high (73; 88%, associated primarily with tetM, but also tetO and tetL). Five isolates (6%) were resistant to erythromycin and clindamycin and 3 isolates were fluoroquinolone-resistant, containing associated mutations in gyrA and parC genes. All isolates were positive for one of four homologous Alpha/Rib family determinants and 1-2 of the three main pilus types., Conclusions: Predominant serotypes were II, Ia, and V. A limited number of clonal types were identified with two STs accounting for about half of the isolates. All strains collected in this study were susceptible to beta-lactam antibiotics and vancomycin. Typical of most GBS, these isolates were positive for single alpha-like family protein, serine-rich repeat gene, as well as 1-2 pilus determinants.

The significance of the complex bacterial ecosystem in the human body and the impediment of the mammalian membrane against many antibiotics together emphasize the necessity to develop antimicrobial agents with precise antimicrobial and cell-penetrating activities. A simple and feasible method for generating dual-function antimicrobial peptides inspired by highly hydrophobic peptide pheromone and cationic cell-penetrating peptides is presented. Furthermore, the extension of the peptide candidate library is achieved by modifying the charged domain. The bacteria-selective peptides L1, L2, L10, and L11 kill Streptococcus agalactiae by disrupting the membrane structure, and the targeted mechanism is suggested where the peptides offset the entrapment of S. agalactiae rather than of other bacteria. Moreover, L2 and L10 possess intracellular antibacterial activity and carrier property, which is mainly dependent on endocytosis. Given their suitable biocompatibility, high tolerance, no drug resistance, and effective antimicrobial capacity in a mouse mastitis model, L2 and L10 can be powerful weapons against S. agalactiae pathogen infection.

This study was designed to compare the performance of GeneXpert® and GenomEra® group B streptococcus (GBS) PCR assays, held up against standard culture of GBS performed with and without broth pre-enrichment. In Denmark, the strategy for preventing early onset GBS infection (EOGBS) is risk factor based. Three hundred and sixty six women fulfilling one or more of the criteria for presence of risk factors for EOGBS were prospectively included. Rectovaginal swab samples were taken intrapartum and tested bed-site by the GenomEra® and the GeneXpert® GBS PCR assays and cultured at the microbiology laboratory using Granada agar plates with and without prior growth of sampling material in selective enrichment broth. Among 366 participants tested intrapartum, 99 were GBS-positive by culture, 95 by GenomEra, and 95 by GeneXpert. Compared with culture, the GenomEra and the GeneXpert performed with a sensitivity of 91.8% and 91.7% and a specificity of 98.1% and 97.3%, respectively. A combined reference standard was established by defining true positives as either culture-positive samples or culture-negative samples where both the GeneXpert and the GenomEra GBS PCR assays were positive. Using this, the sensitivity increased to 92.2% and the specificity to 99.6% for GenomEra and to 92.0% and 96.8% for GeneXpert. The use of selective broth enrichment found only three additional GBS culture-positive samples. The performance of the two PCR methods examined was very similar and close to the findings by culture, and both PCR assays are thus applicable as rapid intrapartum bed-site tests.

Background: Clindamycin is a lincosamide antibiotic used to treat staphylococcal and streptococcal infections. Reports of clinical Streptococcus agalactiae isolates with the rare lincosamide resistance/macrolide susceptibility (L R /M S ) phenotype are increasing worldwide. In this study, we characterised three clinical S. agalactiae strains with the unusual L phenotype from China., Methods: Three clinical S. agalactiae strains, Sag3, Sag27 and Sag4104, with the L phenotype were identified from 186 isolates collected from 2016 to 2018 in Shanghai, China. The MICs of clindamycin, erythromycin, tetracycline, levofloxacin, and penicillin were determined using Etest. PCR for the lnu(B) gene was conducted. Whole genome sequencing and sequence analysis were carried out to investigate the genetic context of lnu(B) . Efforts to transfer lincomycin resistance by conjugation and to identify the circular form by inverse PCR were made., Results: Sag3, Sag27, and Sag4104 were susceptible to erythromycin (MIC ≤0.25 mg/L) but resistant to clindamycin (MIC ≥1 mg/L). lnu(B) was found to be responsible for the L phenotype. lnu(B) in Sag3 and Sag27 were chromosomally located in an aadE-spw-lsa(E)-lnu(B) resistance gene cluster adjacent to an upstream 7-kb tet(L)-cat resistance gene cluster. Two resistance gene clusters were flanked by the IS6-like element, IS1216. Sag4104 only contained partial genes of aadE-spw-lsa(E)-lnu(B) resistance gene cluster and was also flanked by IS1216., Conclusion: These results established the presence of the L phenotype associated with lnu(B) in clinical S. agalactiae isolates in China. The lnu(B) -containing multi-resistance gene cluster possibly acts as a composite transposon flanked by IS1216 and as a vehicle for the dissemination of multidrug resistance among S. agalactiae ., Competing Interests: Competing interestsThe authors declare that they have no competing interests.

The core PI-2b pilus present in "hypervirulent" ST-17 Streptococcus agalactiae strains consists of three pilin subunits (Spb1, Ap1 and Ap2) assembled by sortase SrtC1 and cell-wall anchored by Srt2. Spb1 was shown to be the major pilin and Ap2 the anchor pilin. Ap1 is a putative adhesin. Two additional genes, orf and lep, are part of this operon. The contribution of Lep and Ap1 to the biogenesis of the PI-2b pilus was investigated. Concerning the role of PI-2b, we found that higher PI-2b expression resulted in higher adherence to human brain endothelial cells and higher phagocytosis by human THP1 macrophages., (Copyright © 2018 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

Streptococcus agalactiae (S. agalactiae) has re-emerged as a mastitis pathogen among Norwegian dairy cows. The Norwegian cattle health services recommend that infected herds implement measures to eradicate S. agalactiae, this includes a screening of milk samples from all lactating cows. The performance of the qPCR-test currently in use for this purpose has not been evaluated under field conditions. The objective of this study was to estimate the sensitivity and specificity of the real-time qPCR assay in use in Norway (Mastitis 4 qPCR, DNA Diagnostics A/S, Risskov, Denmark) and compare it to conventional bacteriological culturing for detection of S. agalactiae in milk samples. Because none of these tests are considered a perfect reference test, the evaluation was performed using latent class models in a Bayesian analysis. Aseptically collected cow-composite milk samples from 578 cows belonging to 6 herds were cultured and tested by qPCR. While 37 (6.4%) samples were positive for S. agalactiae by bacteriological culture, 66 (11.4%) samples were positive by qPCR. The within-herd prevalence in the six herds, as estimated by the latent class models ranged from 7.7 to 50.8%. At the recommended cut-off (cycle threshold 37), the sensitivity of the qPCR was significantly higher at 95.3 (95% posterior probability interval [PPI] [84.2; 99.6]) than that of bacteriological culture at 58.2 (95% PPI [43.8; 74.4]). However, bacterial culture had a higher specificity of 99.7 (95% PPI [98.5; 100.0]) compared to the qPCR at 98.5 (95% PPI [94.6; 99.9]). The median estimated negative predictive values of qPCR was consistently higher than those of the BC at all estimated prevalences, and the superiority of the qPCR increased with increasing within-herd prevalence. The median positive predictive values of BC was in general higher than the estimates for the qPCR, however, at the highest prevalence the predictive ability of both tests were similar., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In a previous study, we reported that human milk oligosaccharides (HMOs) isolated from five donor milk samples possessed antimicrobial and antibiofilm activity against Streptococcus agalactiae, also known as Group B Streptococcus or GBS. Herein, we present a broader evaluation of the antimicrobial and antibiofilm activity by screening HMOs from 14 new donors against three strains of GBS and two of the ESKAPE pathogens of particular interest to child health, Staphylococcus aureus and Acinetobacter baumannii. Growth and biofilm assays showed that HMOs from these new donors possessed antimicrobial and antibiofilm activity against all three strains of GBS, antibiofilm activity against methicillin-resistant S. aureus strain USA300, and antimicrobial activity against A. baumannii strain ATCC 19606.

A multiplex polymerase chain reaction (mPCR) was developed for simultaneous detection (single reaction) of genes specific to five frequent clinically relevant β-hemolytic streptococcal species: Streptococcus pyogenes (Spy1258), Streptococcus agalactiae (cfb and cpn60), Streptococcus dysgalactiae subsp. equisimilis (16S-23S intergenic spacer) , S. equi subsp. zooepidemicus (esaA and sorD), and Streptococcus anginosus group (moaC). No cross-reaction was observed with other bacterial species. This test was validated and successfully used with 725 clinical isolates involved in pathological conditions in Thailand and collected between March 2014 and December 2015. Results showed that S. agalactiae, mainly serotype III, was the most common Streptococcus isolated from invasive diseases. This assay should be useful for laboratory identification and surveillance of human infections by these species., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The effects of oral vaccination by two immune routes (gavage and mixed fodder administration) using a recombinant DNA vaccine SL7207-pVAX1-sip against Streptococcus agalactiae were assessed. SL7207-pVAX1-sip significantly enhanced various innate immune responses of tilapia, such as total serum protein, superoxide dismutase activity, lysozyme activity, complement C3 concentration in serum, serum antibacterial activity, and interleukin 1β and tumor necrosis factor-α. Vaccinated fish had higher relative percent survival values (57% and 63% for gavage group and mix fodder administration, respectively) at 10 weeks after S. agalactiae infection. When administered mixed fodder, the DNA vaccine SL7207-pVAX1-sip against S. agalactiae may produce more effective protection. These findings can promote the application and development of DNA vaccines in aquaculture., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Pathogenic bacteria are responsible for several diseases in humans and in a variety of hosts. Detection of pathogenic bacteria is imperative to avoid and/or fight their potential harmful effects. This work reports on the first amperometric biosensor for the rapid detection of Streptococcus agalactiae (S. agalactiae). The biosensor relies on a single biotinylated antibody that immobilizes the bacteria on a screen-printed carbon electrode while is further linked to a streptavidin-conjugated HRP reporter. The biotinylated antibody provides selectivity to the biosensor whereas serves as an anchoring point to the reporter for further amplification of the electrochemical signal. The resultant immunosensor is simple, responds rapidly, and allows for the selective and highly sensitive quantification of S. agalactiae cells in a concentration range of 10 1 -10 7 CFUml -1 , with a detection limit of 10CFUml -1 . The approach not only enables a rapid detection and quantification of S. agalactiae in environmental samples but also opens up new opportunities for the simple fabrication of electrochemical immunosensors for different target pathogens., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A multicenter collection comprising of 171 Streptococcus agalactiae isolates from pregnant women recovered between 2007 and 2010 and 46 from unmatched neonates with invasive infections was subjected to antimicrobial susceptibility testing and genetic characterization. High rates of erythromycin resistance (20.47%) were observed only in isolates from pregnant women. ST1 was dominant in the vaginal colonization, whereas the hypervirulent ST-17 clone was detected in 67.39% of neonatal infections., (Copyright © 2014 Elsevier Inc. All rights reserved.)

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Intramammary infection (IMI) from the environment and infected quarters can cause co-infection. The objective of this study was to determine the ability of coagulase-negative staphylococci (CNS) to survive in the same environment as Staphylococcus aureus, Streptococcus agalactiae, and Escherichia coli as major pathogens. In total, 15 and 242 CNS strains were used in Experiment I and Experiment II, respectively. Both experiments were separated into three conditions: culture with CNS 24 h before (PRIOR), after (AFTER), and at the same time (EQUAL). The lack of a clear zone, regardless of size, was determined to be the key to the survival of both. The CNS species' percentages of survival against major pathogens were tested using Fisher's exact test. Differences in the percentages of survival were evident among the CNS species in all conditions. For the PRIOR condition, all CNS mostly survived when living with major strains; however, S. chromogenes could degrade S. agalactiae. Although most CNS strains were degraded in the AFTER and EQUAL conditions, some strains of S. hominis and S. simulans could resist S. aureus and S. agalactiae. In conclusion, some specific strains of CNS are able to survive in an environment with major pathogens. Research into the survival strains may indicate that the concept of novel bacteria with bacteriolytic capabilities might be possible as a novel mastitis treatment. [ABSTRACT FROM AUTHOR]

Mastitis disease causes significant economic losses in dairy farms by reducing milk production, increasing production costs, and reducing milk quality. Streptococcus agalactiae continues to be a major cause of mastitis in dairy cattle. To date, there has been no approved multi-epitope vaccine against this pathogen in the market. In the present study, an efficient multi-epitope vaccine against S. agalactiae, the causative agent of mastitis, was designed using various immonoinformtics approaches. Potential epitopes were selected from Sip protein to improve vaccine immunogenicity. The designed vaccine is more antigenic in nature. Then, linkers and profilin adjuvant were added to enhance the immunity of vaccines. The designed vaccine was evaluated in terms of molecular weight, PI, immunogenicity, Toxicity, and allergenicity. Prediction of three-dimensional (3 D) structure of multi-epitope vaccine, followed by refinement and validation, was conducted to obtain a high-quality 3 D structure of the designed multi-epitope vaccine. The designed vaccine was then subjected to molecular docking with Toll-like receptor 11 (TLR11) receptor to evaluate its binding efficiency followed by dynamic simulation for stable interaction. In silico cloning approach was carried out to improve the expression of the vaccine construct. These analyses indicate that the designed multi-epitope vaccine may produce particular immune responses against S. agalactiae and may be further helpful to control mastitis after in vitro and in vivo immunological assays. [ABSTRACT FROM AUTHOR]

Streptococcus agalactiae is a well-known pathogen in humans and food-producing animals. Therefore, this bacterium is a paradigmatic example of a pathogen to be controlled by a One Health approach. Indeed, the zoonotic and reverse-zoonotic potential of the bacteria, the prevalence of Group B Streptococci (GBS) diseases in both human and animal domains, and the threatening global situation on GBS antibiotic resistance make these bacteria an important target for control programs. An epidemiological analysis using a public database containing sequences of S. agalactiae from all over the world was conducted to evaluate the frequency and evolution of antibiotic resistance genes in those isolates. The database we considered (NCBI pathogen detection isolate browser—NPDIB) is maintained on a voluntary basis. Therefore, it does not follow strict epidemiological criteria. However, it may be considered representative of the bacterial population related to human diseases. The results showed that the number of reported sequences increased largely in the last four years, and about 50% are of European origin. The frequency data and the cluster analysis showed that the AMR genes increased in frequency in recent years and suggest the importance of verifying the application of prudent protocols for antimicrobials in areas with an increasing frequency of GBS infections both in human and veterinary medicine. [ABSTRACT FROM AUTHOR]

Background: Mastitis is one of the most expensive diseases in the dairy industry. It causes heavy monetary losses by decreasing milk production and treatment cost. Streptococcus agalactiae, the cause of contagious bovine mastitis, possesses various virulence factors that contribute to pathogenicity. Aims: The main aim of the study was to evaluate the distribution of virulence genes of S. agalactiae. Methods: In the current work, 98 Streptococcus species were isolated from 320 milk samples, collected from Veterinary Clinical Complex, Junagadh. Out of the isolates, 42 S. agalactiae isolates were used for virulence genes detection. Results: All Streptococcus spp. were confirmed at genus level by targeting tuf gene, and S. agalactiae was identified at species level by targeting 16S rRNA gene. For virulence gene detection, scpB, cfb, and cylE genes were targeted. Of 42 S. agalactiae isolates, 15, 16, and 10 isolates possessed scpB, cfb, and cylE genes, respectively. Conclusion: This study aids us to know virulence characteristics and mechanisms responsible for the development of new strains in mastitis epidemiology in response to prevention and control strategies. [ABSTRACT FROM AUTHOR]

Streptococcus agalactiae causes sepsis and meningitis in neonates, presenting substantial clinical challenges. Type VII secretion system (T7SS), an important secretion system identified in Mycobacterium sp. and Gram-positive bacteria, was recently characterized in S. agalactiae and considered to contribute to its virulence and pathogenesis. In the present study, 128 complete genomic sequences of S. agalactiae were retrieved from GenBank to build a public dataset, and their sequences, capsular types, and clonal complexes were determined. Polymerase chain reaction (PCR) screening and genomic sequencing were conducted in an additional clinical dataset. STs and capsular types were determined using PCR. Eleven different types of T7SS were detected with similarities in gene order but differences in gene content. Strains with incomplete T7SS or lack of T7SS were also identified. Deletion, insertion, and segmentation of T7SS might be related to insertion sequences. The genetic environment of T7SS in S. agalactiae was also investigated and different patterns were identified downstream the T7SS, which were related to the diversity of T7SS putative effectors. The T7SS demonstrated possible sequence type (ST)-dependent diversity in both datasets. This work elucidated detailed genetic characteristics of T7SS and its genetic environment in S. agalactiae and further identified its possible ST-dependent diversity, which gave a clue of its mode of transmission. Further investigations are required to elucidate the underlying mechanisms and its functions. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the potential causes of the summer mortality syndrome affecting the earthen pond cultured Nile tilapia, Oreochromis niloticus in some Egyptian farms. A total of 100 moribund O. niloticus showing non-specific clinical signs of septicemia and mortality (30- 65%) were collected from five farms at Tolombat 7, Kafr El-Sheikh, Egypt, during June 2019. All the fish farms share the same water source and perform some bad management practices. Inadequate water quality measures were noticed in all the investigated farms. Molecular detection of tilapia lake virus (TiLV) using PCR confirmed the non-existence of the TiLV in all examined specimens. A total of 19 pathogenic bacterial isolates were obtained from moribund O. niloticus: Streptococcus agalactiae (14), Aeromonas hydrophila (3), and Vibrio cholera (2). The predominance of Streptococcus agalactiae infections points to its intense involvement in such mortalities. S. agalactiae was confirmed by 16s rRNA gene sequencing and phylogenetic analysis. The PCR detection of virulence genes showed existence of Hyl, cylE, scpB and camp genes in all S. agalactiae strains. Isolates of S. agalactiae showed variable susceptibility to the tested antibiotics with high resistance against ampicillin, amoxicillin and gentamycin. Infections were associated with several pathological alterations in naturally infected fish. The pathogenicity of S. agalactiae was confirmed in O. niloticus (90 % cumulative mortality). The data in the present study proved that the tilapia summer mortality syndrome is multifactorial. Thus, good managemental practices and water quality measures are recommended to minimize fish mortality. [ABSTRACT FROM AUTHOR]

Objectives: Streptococcus agalactiae is a zoonotic human and animal pathogen that causes global economic losses in aquaculture and fatal outcomes in Tilapia. This study aimed to identify S. agalactiae isolated from different fish sources intended for human consumption phenotypically and genotypically and to characterize the virulence-associated genes fbsA (fibrinogen-binding protein FbsA), cfb (CAMP factor), and pbp1A/ponA (penicillin-binding protein 1A). Materials and Methods: Three hundred Nile Tilapia fish (Oreochromis niloticus) were collected from different farms and retail shops in Dakahlia and Damietta, Egypt, during the summer of 2020. The samples were examined using routine phenotypic methods, then characterized using polymerase chain reaction (PCR) targeting S. agalactiae-specific dltS gene. All S. agalactiae isolates were examined for the susceptibility to ten antimicrobial agents by the disc diffusion method. The virulence-associated genes (fbsA, cfb, and pbp1A/ponA) were characterized using multiplex-PCR. Results: Streptococcus agalactiae was detected in 7% (n = 21/300) samples. The isolates showed high resistance against ampicillin and erythromycin (20/21; 95%) for each. The most predominant antibiotypes through isolates were P, CN, SXT, CRO, TE, CTX, E, AMP, at 10.5% for each antibiotype. A total of 19 (90.5%) of S. agalactiae isolates showed multi-drug resistance (MDR), and those were recovered from market Tilapia fish. The virulence-associated genes (fbsA, cfb, and pbp1A/ ponA) were identified in the S. agalactiae as 100%, 76%, and 52%, respectively. Conclusions: The MDR S. agalactiae detected in raw Tilapia fish pose a significant health hazard to consumers due to their zoonotic characteristics. [ABSTRACT FROM AUTHOR]

The present study was conducted to investigate the effects of dietary cinnamaldehyde nanoemulsion (CNE) on growth, digestive activities, antioxidant and immune responses and resistance against Stre ptococcus agalactiae (S. agalactiae) in Nile tilapia. Four experimental diets were formulated containing CNE at levels of 0, 100, 200 and 300 mg/kg diet for 12 weeks. At the end of the experiment, all fish were challenged by S. agalactiae. The results showed that the final body weight was increased in fish groups fed 200 and 300 mg CNE/kg diet by 18.4 and 17.2% with respect to the control group. Moreover, feed conversion ratio and digestive enzymes' activities were improved in groups fed 200 and 300 then 100 mg of dietary CNE/kg diet. Groups fed CNE exhibited a significant increase in serum immune-related parameters when compared with control group. Additionally, the hypocholesterolemic effects was achieved after CNE feeding unlike the control group in a dose dependent manner. With increasing dietary CNE levels, genes expression of cytokines and antioxidant enzymes were upregulated. Less severe adverse clinical symptoms and respectable cumulative mortalities associated with S. agalactiae infection were observed in fish fed CNE. To our knowledge, this study was the first offering a protective effect of CNE against S. agalactiae infection in Nile tilapia with a maximum down-regulation of cylE and hylB virulence genes expression noticed in group fed 300 mg of CNE/kg diet (up to 0.10 and 0.19- fold, respectively). Therefore, the present study recommended that an incorporation of CNE at level of 300 mg/kg diet for Nile tilapia could promote their growth, enhance their immunity and antioxidant status and provide protection against virulent S. agalactiae. • Growth performance of Nile tilapia can be boosted by dietary CNE. • CNE supplemented diets potentiated the expression of SOD, CAT, GPx genes in Nile tilapia. • Dietary CNE can modulate immune responses of Nile tilapia. • Dietary CNE could reinforce resistance against Streptococcus agalactiae infection in Nile tilapia. [ABSTRACT FROM AUTHOR]

Microfibril-associated glycoprotein 4 (MFAP4), a pattern recognition-like molecule with a fibrinogen-like domain (FBG), has the ability to combine and agglutinate pathogens, playing an essential role in the first line of innate immune defense. In this study, the sequence of Nile tilapia (Oreochromis niloticus) microfibril-associated glycoprotein 4 (OnMFAP4) open reading frame (ORF) was amplified and identified. The ORF of OnMFAP4 is 720 bp of nucleotides and codes for 239 amino acids. Spatial mRNA encoding analysis indicated that OnMFAP4 was highly produced in liver, intestine and head kidney in healthy tilapia, and with the lowest expression in muscle. After challenges with Streptococcus agalactiae (S. agalactiae) and Aeromonas hydrophila (A. hydrophila), the expression of OnMFAP4 mRNA was prominently produced in the liver, spleen and head kidney. The up-regulation of OnMFAP4 expression was also presented in head kidney monocytes/macrophages (MO/MΦ) and hepatocytes. Recombinant OnMFAP4 ((r)OnMFAP4) could bind and agglutinate both bacterial pathogens. Moreover, (r)OnMFAP4 could take part in the modulation of inflammation and phagocytosis. In conclusion, this study revealed that OnMFAP4 might take effect in host defense against bacterial infection in Nile tilapia, with agglutination and opsonization capability to bacterial pathogens. • The OnMFAP4 expression was significantly up-regulated following challenges with S. galactiae and A. hydrophila. • Recombinant OnMFAP4 possessed an ability to bind and agglutinate S. agalactiae and A. hydrophila. • Recombinant OnMFAP4 was able to participate in the regulation of inflammatory in monocytes/macrophages. • Recombinant OnMFAP4 could strengthen phagocytosis in monocytes/macrophages. [ABSTRACT FROM AUTHOR]

The present study aimed to assess the possible effects of Assam tea (Camellia sinensis) extract (ATE) on growth performances, immune responses, and disease resistance of Nile tilapia, Oreochromis niloticus against Streptococcus agalactiae. Five levels of ATE were supplemented into the based diet at 0, 1, 2, 4, and 8 g kg−1 feed of Nile tilapia fingerlings (10.9 ± 0.04 g initial weight) in triplicate. After four and eight weeks of feeding, fish were sampled to determine the effects of the tea supplements upon their growth performance, as well as serum and mucosal immune responses. A disease challenge using S. agalactiae was conducted at the end of the feeding trial. Fish fed ATE revealed significantly improved serum lysozyme, peroxidase, alternative complement (ACH50), phagocytosis, and respiratory burst activities compared to the basal control fed fish (P < 0.05). The mucus lysozyme and peroxidase activities were ameliorated through ATE supplementation in the tilapia diets. Supplementation of ATE significantly (P < 0.05) enhanced final body weight, weight gain, and specific growth rate; while a decreased feed conversion ratio was revealed at 2 g kg−1 inclusion level, after four and eight weeks. Challenge test showed that the relative percent survival (RSP) of fish in each treatment was 33.33%, 60.00%, 83.33%, 76.68%, and 66.68% in groups fed 0, 1, 2, 4, and 8 g kg−1, respectively. In summary, diets supplemented with ATE especially at 2 g kg−1 increased the humoral and mucosal immunity, enhanced growth performance, and offered higher resistance against S. agalactiae infection in Nile tilapia. • DietaryAssam tea extract (ATE) significantly improved growth rate and reduced the FCR. • Significant enhances in the skin mucus and serum immunity were found in tilapia fed ATE. • Significant reduction in mortality was observed in tilapia fed ATE against Streptococcus agalactiae. • Supplementation of ATE at 2 g kg−1 is recommended for better growth , immune response and resistance against S. agalactiae. [ABSTRACT FROM AUTHOR]

Streptococcus. agalactiae has been appearing as a vital human pathogen and a gradually important cause of aggressive infections in immunocompromised adults and older, the aim of the study was to find the effect of inflammatory cytokine (interleukin 8) and immune reactive molecules (CD79 and CD54 molecules) on pathogenesis of S. agalactiae that isolated from aborted women. A total of 100 aborted women aged between (18–42) years, were involved in this study. Placentas specimens were cultured to isolate the Streptococcus agalactiae, the level of cytokine in the serum was measured by commercial ELISA tests, while CD molecules was estimated by immunohistochemistery assay. Our results showed that there was streptococcal isolates from Placentas specimens, Specific isolation and identification were done for S. agalactiae. Significant difference could be found in serum levels of inflammatory cytokine (P≤ 0.05) between these two investigated groups (infected and uninfected with S. agalactiae) in addition to high expression for CD79 and CD54 in infected women as compare with non S. agalactiae infected women. [ABSTRACT FROM AUTHOR]

Abstract In this study, the tilapia was orally vaccinated by the attenuated Streptococcus agalactiae (S. agalactiae) strain YM001, and the distribution and the pathological effect of strain YM001 in different intestinal segments of tilapia were evaluated by real-time PCR(qPCR), immunohistochemistry(IHC) and histomorphology. The qPCR results showed that the number of bacteria was the highest in the intestinal tracts at 12 h post oral gavage in the YM001 group, then began to decrease sharply and eliminated at 7 d. And the number of bacteria was highest in the foregut, hindgut, and rectum at 12 h, 24 h, and 3 d, respectively. IHC indicated that bacteria mainly distributed in the margin epithelium and the goblet cells at 12 h - 24 h, and in the submucosa and muscle layer in the YM001 group in 3 d post gavage, then almost disappeared at 7 d. Histological examination of intestines post gavage displayed that an inflammation was observed at 7 d in the YM001 group and the intestinal structure was fully recovered at 15 d. and the intestinal structure was fully recovered at 15 d. Conclusion: The attenuated S. agalactiae vaccine strain YM001 could enter the intestinal tissue after oral gavage and had a strong spatial and temporal selectivity in the intestinal tract, which could cause obvious mucosal immune response and mild pathological reaction, but the pathological change could be gradually repaired with the extinction of bacteria in the body. Highlights • The attenuated S. agalactiae vaccine strain YM001 could enter the intestinal tissue. • The strain YM001 had a strong spatial and temporal selectivity in the intestinal tract. • Fish can be repaired with the extinction of bacteria in the body. [ABSTRACT FROM AUTHOR]

Streptococcus agalactiae and Candida albicans often co-colonize the female genital tract, and under certain conditions induce mucosal inflammation. The role of the interaction between the two organisms in candidal vaginitis is not known. In this study, we found that co-infection with S. agalactiae significantly attenuated the hyphal development of C. albicans, and that EFG1-Hwp1 signal pathway of C. albicans was involved in this process. In a mouse model of vulvovaginal candidiasis (VVC), the fungal burden and the levels of pro-inflammatory cytokines, IL-1β, IL-6 and TNF-α showed a increase on co-infection with S. agalactiae, while the level of TH17 T cells and IL-17 in the cervicovaginal lavage fluid were significantly decreased. Our results indicate that S. agalactiae inhibits C. albicans hyphal development by downregulating the expression of EFG1-Hwp1. The interaction between S. agalactiae and C. albicans may attenuate host vaginal mucosal TH17 immunity and contribute to mucosal colonization by C. albicans. [ABSTRACT FROM AUTHOR]

A commercial red hybrid tilapia was experimented with S. agalactiae infection under influences of heat stress which indicated by plasma malondialdehyde (MDA) and erythrocyte superoxide dismutase (SOD) as biomarkers of stress. To achieve these objectives, 110 red hybrid tilapia in good health were divided into five groups of 22 fish each. Group A was challenged with 2.3 × 109 CFU of S. agalactiae and exposed to heat stress at 33 ± 0.5°C on day 1. Group B was challenged on day 1 as in Group A but heat stress was introduced on day 7 post challenge (pc). Group C was exposed to heat stress on day 1 and challenged on day 7 pc while groups D and E served as a positive and negative controls respectively. Blood samples were collected at days 0, 3, 7, 10 and 14 for MDA and SOD analysis. Groups A and B recorded high mortality following exposure to heat stress and bacteria inoculation, with group A reaching 100% mortality at day 7 post inoculation. Overall, Groups A, B, C and Group D showed pattern of increase in MDA level as early as day 3 and decrease pattern for SOD activity. Group E did not show any significant difference in MDA level throughout the study period. Clinical signs such as erratic swimming, exopthalmia, skin haemorrhage and cloudy eye were predominantly observed in group A 24 h post inoculation. Based on the findings of this study, it was concluded that heat stress plays crucial role in the pathogenesis of S. agalactiae, via alteration of the oxidant defence system. [ABSTRACT FROM AUTHOR]

Streptococcus agalactiae (Group B streptococcus, GBS) is highly adapted to humans, where it is a normal constituent of the intestinal and vaginal flora. Yet, GBS has highly invasive potential and causes excessive inflammation, sepsis, and death at the beginning of life, in the elderly and in diabetic patients. Thus, GBS is a model pathobiont that thrives in the healthy host, but has not lost its potential virulence during coevolution with mankind. It remains incompletely understood how the innate immune system contains GBS in the natural niches, the intestinal and genital tracts, and which molecular events underlie breakdown of mucocutaneous resistance. Newborn infants between days 7 and 90 of life are at risk of a particularly striking sepsis manifestation (late-onset disease), where the transition from colonization to invasion and dissemination, and thus from health to severe sepsis is typically fulminant and not predictable. The great majority of late-onset sepsis cases are caused by one clone, GBS ST17, which expresses HvgA as a signature virulence factor and adhesin. In mice, HvgA promotes the crossing of both the mucosal and the blood-brain barrier. Expression levels of HvgA and other GBS virulence factors, such as pili and toxins, are regulated by the upstream two-component control system CovR/S. This in turn is modulated by acidic epithelial pH, high glucose levels, and during the passage through the mouse intestine. After invasion, GBS has the ability to subvert innate immunity by mechanisms like glycerinaldehyde-3-phosphate-dehydrogenase-dependent induction of IL-10 and b-protein binding to the inhibitory phagocyte receptors sialic acid binding immunoglobulinlike lectin 5 and 14. On the host side, sensing of GBS nucleic acids and lipopeptides by both Toll-like receptors and the inflammasome appears to be critical for host resistance against GBS. Yet, comprehensive models on the interplay between GBS and human immune cells at the colonizing site are just emerging. [ABSTRACT FROM AUTHOR]

Abstract: Streptococcus agalactiae is an emerging pathogen in Nile tilapia (Oreochromis niloticus) worldwide. To investigate aspects of the epidemiology, transmission and virulence of S. agalactiae infections, nine outbreaks of meningoencephalitis and septicemia in Nile tilapia farms in Brazil were analyzed. Records from the outbreaks revealed large variation in the weight of fish affected, high mortality, and disease occurrence at water temperatures above 26°C. S. agalactiae was isolated from diseased fish from all farms, and 29 strains were identified by phenotypic tests and 16S rRNA gene sequencing. Five strains from different geographic origins were selected to determine the 50% lethal dose (LD50). All strains were highly virulent; for example, strain SA 20-06 had an LD50 of 90 bacteria. To investigate S. agalactiae transmission, we conducted cohabitation assays with diseased and healthy fish and fish challenges using an immersion bath or gill inoculation. Strain SA 20-06 was used in all assays. The disease was reproduced with characteristic clinical signs and S. agalactiae was reisolated in all trials. The infection route studies were identified as by direct contact or through the water. In conclusion, S. agalactiae, a major pathogen of Nile tilapia in Brazil, exhibited high virulence, regardless of the geographic origin of the isolated strains. [Copyright &y& Elsevier]

This narrative review describes the public health importance of four most common bacterial meningitis agents, Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, and S. agalactiae (group B Streptococcus). Three of them are strict human pathogens that normally colonize the nasopharynx and may invade the blood stream to cause systemic infections and meningitis. S. agalactiae colonizes the genito-gastrointestinal tract and is an important meningitis agent in newborns, but also causes invasive infections in infants or adults. These four bacteria have polysaccharide capsules that protect them against the host complement defense. Currently licensed conjugate vaccines (against S. pneumoniae, H. influenza, and N. meningitidis only but not S. agalactiae) can induce protective serum antibodies in infants as young as two months old offering protection to the most vulnerable groups, and the ability to eliminate carriage of homologous serotype strains in vaccinated subjects lending further protection to those not vaccinated through herd immunity. However, the serotype-specific nature of these vaccines have driven the bacteria to adapt by mechanisms that affect the capsule antigens through either capsule switching or capsule replacement in addition to the possibility of unmasking of strains or serotypes not covered by the vaccines. The post-vaccine molecular epidemiology of vaccine-preventable bacterial meningitis is discussed based on findings obtained with newer genomic laboratory surveillance methods. [ABSTRACT FROM AUTHOR]

Abstract: A multiplex PCR assay for the identification of serotypes Ia to IX of Streptococcus agalactiae was developed. By using a single PCR reaction containing a mix of 19 primers the assay identified each serotype by the analysis of the unique two or three bands pattern on agarose gel. [Copyright &y& Elsevier]

Four weeks feeding trial was conducted to assess the in vivo probiotic potentials of three host-associated Bacillus species in O. niloticus. The fish were divided into five treatment groups and fed with diets containing no bacteria (group CT), B. velezensis TPS3N (group V), B. subtilis TPS4 (group S), B. amyloliquefaciens TPS17 (group A) and a 5th group which comprised the combination of the three Bacillus species at a ratio 1:1:1 (group CB). At the end of the feeding trial, enhanced growth performance in terms of final weight (FW), weight gain (WG), specific growth rate (SGR) as well as significantly lower (P <.05) feed conversion ratio (FCR) were recorded in the Bacillus treatment groups with the CB group having the best performance. Improved immune and biochemical (P <.05) (nitric oxide (NO), immunoglobulin M (IgM), lysozyme (LZM), acid phosphatase (ACP), and alkaline phosphatase (AKP)) indexes, antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)) and digestive enzymes (lipase and trypsin) were also recorded in the treatment groups relative to the CT group. Significantly lower (P <.05) GOT and MDA activities were also observed in the V, S, A, and CB groups than the CT groups. Growth-related genes GHR-1 and IGF-1 were upregulated significantly (P <.05) in both liver and head kidney (HK) of fish fed Bacillus supplemented diets. Likewise, the CB group induced significant upregulation (P <.05) of TNF-α, TLR-2, IgM (except in the liver) and C-LYZ in both liver and HK. A subsequent challenge test with S. agalactiae resulted in cumulative mortalities (%) of 60%, 33%, 27%, 20%, and 13% in the CT, V, S, A, and CB treatment groups respectively. It was therefore concluded from this experiment that dietary inclusion of the Bacillus species singularly or in combination could elicit probiotic effects and protect O. niloticus against S. agalactiae infection. • This study provides information on the effects of host-associated Bacillus species in tilapia culture. • Dietary inclusion of the Bacillus species improved growth, digestive enzymes, and immunity of tilapia. • The Bacillus species protected tilapia against S. agalactiae infection. • Combination of the Bacillus species in the diet of tilapia showed the best probiotic effects. [ABSTRACT FROM AUTHOR]

Fish farming represents an important and healthy source of protein for human nutrition. Currently, Nile tilapia (Oreochromis niloticus) is the second most raised fish species worldwide, and its fillet plays an important role in the international trade of fish meat. In Brazil, fish slaughterhouses submitted to the Federal Meat Inspection Service detected lesions on tilapia fillets, which cause condemnation and economic losses to farmers and companies. The main etiologic agents associated with these fillet lesions have never been addressed. This study aimed to characterize the anatomopathology and etiologic agents involved in Nile tilapia fillet lesions. From May to September 2017, 70 fillets of Nile tilapia discarded as improper for human consumption at the inspection line were sampled, macroscopically characterized, and submitted to histopathology. In addition, Streptococcus agalactiae and Francisella noatunensis subsp. orientalis (Fno) were detected by PCR and qPCR, respectively. Out of all analyzed samples, 67% were positive either for Streptococcus agalactiae , Fno , or both. Three macroscopic patterns were identified, being two associated with bacterial pathogens. 85% of the Fno positive fillets had a black dot pattern and 90% of the S. agalactiae positive fillets had a cavity pattern on the surface of the fillet. Irregular white areas were not positive for any agent and were trauma related. The microscopic findings were pyogranulomatous and necrotizing myositis of varying degrees and distribution. The rate of discard in the lots affected by bacteria ranged from 0.2% to 2% of fillets. This is the first report of Fno as an important cause of fillet discharge in Nile tilapia slaughterhouses. The macroscopic patterns identified may be helpful in suggesting the etiology of these lesions and preventing economic loss. • Streptococcus agalactiae is the main pathogen associated with Nile tilapia fillet lesions. • Fno is an important cause of fillet discharge in Nile tilapia slaughterhouses. • Macroscopic patterns are useful in suggesting the etiology of Nile tilapia fillet lesions. [ABSTRACT FROM AUTHOR]

Tilapia (Oreochromis niloticus) farming on Lake Kariba, Zambia has been practiced since early 2000s. In recent years, the industry has experienced disease outbreaks with clinical signs consistent with streptococcus-like infections. Affected fish were growers weighing approximately 200 g or above from farms designated A and B, reared in cages on the lake. The objective of this study was to identify and characterize the causative bacteria of these outbreaks. A total of eighty-six diseased fish were sampled between 2014 and 2016. Bacteria were cultured from internal organs and were characterized by biochemical tests, PCR and sequencing of the 16S rRNA gene or 16S 23S intergenic spacer region. The results showed the prevalence of Lactococcus garvieae at farm A in 2015 and 2016 outbreaks (15/20 and 23/40, respectively) and at farm B (6/20) in 2016. Infection of naïve fish with one isolate of L. garvieae recovered from the outbreaks resulted in clinical signs and mortalities akin of what had been observed during the outbreaks, confirming Koch's postulates. In the 2014 outbreaks, the low prevalence of Streptococcus agalactiae (4/15 and 2/11 respectively at farms A and B) and S. iniae (2/15) at farm A suggests that other pathogens were likely involved in the disease outbreak observed. • Streptococcus agalactiae and Streptococcus iniae isolated from diseased farmed Nile tilapia on Lake Kariba in 2014 • Temporal (2014–16) characterization of Streptococcus-like bacteria shows that Lactococcus garvieae increased in dominance over time • Koch's postulates for Lactococcus garvieae in Nile tilapia are proved [ABSTRACT FROM AUTHOR]