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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.)

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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Zhou, Xie, Xu and Sun.)

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.)

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 Streptococcus 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., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

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.

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.)

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.)