Vaginal Group B Streptococcus Colonization Research Articles

Immunization with Multiple Virulence Factors Provides Maternal and Neonatal Protection against Group B Streptococcus Serotypes.

Group B streptococcus (GBS) commonly colonizes the vaginal tract and is a leading cause of life-threatening neonatal infections and adverse pregnancy outcomes. No effective vaccine is clinically available. Conserved bacterial virulence factors, including those of GBS, have been employed as vaccine components. We investigated serotype-independent protection against GBS by intranasal immunization with six conserved GBS virulence factors (GBSV6). GBSV6 induced systemic and vaginal antibodies and T cell responses in mice. The immunity reduced mouse mortality and vaginal colonization by various GBS serotypes and protected newborn mice of immunized dams against GBS challenge. Intranasal GBSV6 immunization also provided long-lasting protective immunity and had advantages over intramuscular GBSV6 immunization regarding restricting vaginal GBS colonization. Our findings indicate that intranasal immunization targeting multiple conserved GBS virulence factors induces serotype-independent immunity, which protects against GBS infection systemically and vaginally in dams and prevents newborn death. The study presents valuable strategies for GBS vaccine development.

Heterogeneity of the group B streptococcal type VII secretion system and influence on colonization of the female genital tract.

Type VIIb secretion systems (T7SSb) in Gram-positive bacteria facilitate physiology, interbacterial competition, and/or virulence via EssC ATPase-driven secretion of small ɑ-helical proteins and toxins. Recently, we characterized T7SSb in group B Streptococcus (GBS), a leading cause of infection in newborns and immunocompromised adults. GBS T7SS comprises four subtypes based on variation in the C-terminus of EssC and the repertoire of downstream effectors; however, the intraspecies diversity of GBS T7SS and impact on GBS-host interactions remains unknown. Bioinformatic analysis indicates that GBS T7SS loci encode subtype-specific putative effectors, which have low interspecies and inter-subtype homology but contain similar domains/motifs and therefore may serve similar functions. We further identify orphaned GBS WXG100 proteins. Functionally, we show that GBS T7SS subtype I and III strains secrete EsxA in vitro and that in subtype I strain CJB111, esxA1 appears to be differentially transcribed from the T7SS operon. Furthermore, we observe subtype-specific effects of GBS T7SS on host colonization, as CJB111 subtype I but not CNCTC 10/84 subtype III T7SS promotes GBS vaginal colonization. Finally, we observe that T7SS subtypes I and II are the predominant subtypes in clinical GBS isolates. This study highlights the potential impact of T7SS heterogeneity on host-GBS interactions.

Antimicrobial Photodynamic Inactivation: An Alternative for Group B Streptococcus Vaginal Colonization in a Murine Experimental Model.

Streptococcus agalactiae, referred to as Group B Streptococcus (GBS), is a prominent bacterium causing life-threatening neonatal infections. Although antibiotics are efficient against GBS, growing antibiotic resistance forces the search for alternative treatments and/or prevention approaches. Antimicrobial photodynamic inactivation (aPDI) appears to be a potent alternative non-antibiotic strategy against GBS. The effect of rose bengal aPDI on various GBS serotypes, Lactobacillus species, human eukaryotic cell lines and microbial vaginal flora composition was evaluated. RB-mediated aPDI was evidenced to exert high bactericidal efficacy towards S. agalactiae in vitro (>4 log10 units of viability reduction for planktonic and >2 log10 units for multispecies biofilm culture) and in vivo (ca. 2 log10 units of viability reduction in mice vaginal GBS colonization model) in microbiological and metagenomic analyses. At the same time, RB-mediated aPDI was evidenced to be not mutagenic and safe for human vaginal cells, as well as capable of maintaining the balance and viability of vaginal microbial flora. aPDI can efficiently kill GBS and serve as an alternative approach against GBS vaginal colonization and/or infections.

Interspecies Interactions within the Host: the Social Network of Group B Streptococcus.

Group B Streptococcus (GBS) is a pervasive neonatal pathogen accounting for a combined half a million deaths and stillbirths annually. The most common source of fetal or neonatal GBS exposure is the maternal microbiota. GBS asymptomatically colonizes the gastrointestinal and vaginal mucosa of 1 in 5 individuals globally, although its precise role in these niches is not well understood. To prevent vertical transmission, broad-spectrum antibiotics are administered to GBS-positive mothers during labor in many countries. Although antibiotics have significantly reduced GBS early-onset neonatal disease, there are several unintended consequences, including an altered neonatal microbiota and increased risk for other microbial infections. Additionally, the incidence of late-onset GBS neonatal disease remains unaffected and has sparked an emerging hypothesis that GBS-microbe interactions in developing neonatal gut microbiota may be directly involved in this disease process. This review summarizes our current understanding of GBS interactions with other resident microbes at the mucosal surface from multiple angles, including clinical association studies, agriculture and aquaculture observations, and experimental animal model systems. We also include a comprehensive review of in vitro findings of GBS interactions with other bacterial and fungal microbes, both commensal and pathogenic, along with newly established animal models of GBS vaginal colonization and in utero or neonatal infection. Finally, we provide a perspective on emerging areas of research and current strategies to design microbe-targeting prebiotic or probiotic therapeutic intervention strategies to prevent GBS disease in vulnerable populations.

Supplementation of Probiotics in Pregnant Women Targeting Group B Streptococcus Colonization: A Systematic Review and Meta-Analysis.

This systematic review and meta-analysis aimed to determine if probiotic supplementation in pregnancy reduced maternal Group B streptococcus (GBS) recto-vaginal colonization in pregnant women at 35-37 weeks of gestation. Electronic databases (i.e., PubMed, MEDLINE, ClinicalTrials.gov, ScienceDirect, and the Cochrane Library) were searched from inception up to February 2022. We included RCTs assessing the effects of probiotic supplementation in pregnancy on GBS recto-vaginal colonization. The primary outcome was GBS-positive recto-vaginal cultures performed at 35-37 weeks of gestation. Secondarily, we evaluated obstetric and short-term neonatal outcomes. A total of 132 publications were identified; 9 full-length articles were reviewed to finally include 5 studies. Probiotic supplementation reduced vaginal GBS colonization: the GBS positive culture rate was estimated at 31.9% (96/301) in the intervention group compared to 38.6% (109/282) in the control group (OR = 0.62, 95% CI 0.40-0.94, I2 4.8%, p = 0.38). The treatment started after 30 weeks of gestation and was more effective in reducing GBS colonization (OR 0.41, 95% CI 0.21-0.78, I2 0%, p = 0.55). Probiotic administration during pregnancy, namely in the third trimester, was associated with a reduced GBS recto-vaginal colonization at 35-37 weeks and a safe perinatal profile. Whether this new strategy could reduce the exposition of pregnant women to significant doses of antibiotics in labor needs to be evaluated in other trials.

Vertical Transmission, Risk Factors, and Antimicrobial Resistance Patterns of Group B Streptococcus among Mothers and Their Neonates in Southern Ethiopia.

Background Group B Streptococcus (GBS) contributes to maternal and neonatal morbidity and mortality by increasing intrauterine infection or vertical transmission at the time of birth. Despite many efforts to reduce the potential risk of vertical transmission, GBS remains the main cause of serious disease (neonatal sepsis, meningitis, and/or pneumonia) in vulnerable newborns during the first week of life. This study aimed to assess vertical transmission, risk factors, and antimicrobial resistance patterns of GBS among pregnant women and their neonates. Methods A facility-based cross-sectional study was conducted among mothers and their neonates from February to May 2021. A total of 201 pregnant women with their neonates participated in this study. A well-designed questionnaire was used to collect sociodemographic and clinical data. A vaginal swab from mother before delivery and neonatal nasal and ear canal swab samples were taken as soon as after delivery within 30 minutes. Vaginal swabs, neonatal ear canal, and nasal swabs were placed into Todd–Hewitt broth and incubated at 37°C for 18–24 hours at 35–37°C in 5% CO2 conditions and then subcultured on 5% sheep blood agar for 18–48 hours. Presumptive identification of GBS was made by morphology, Gram stain, catalase, and hemolytic activity on sheep blood agar plates. CAMP and bacitracin susceptibility tests were used as confirmatory tests for GBS. Data were analyzed using SPSS version 21. P value ≤0.05 was considered statistically significant. Results Vertical transmission rates of GBS (mother to neonates) were 11.9%. The prevalence of GBS among pregnant women and newborns was 24/201 (11.9%) (95% CI = 7.5–16.9) and 11/201 (5.5%) (95% CI = 2.5–9.0), respectively. The history of prolonged rupture of membranes (AOR = 3.5, CI = 2.2–18.8) and urinary tract infection (AOR = 2.9, CI = 1.7–16.3) were associated factors for maternal GBS colonization. Gestational age of <37 weeks (p=0.008), low birth weight of <2.5 kg (p=0.001), and maternal history of vaginal discharge (p=0.048) were associated factors for neonatal GBS colonization. Low antibiotic resistance was observed for erythromycin 8.6%, clindamycin 5.7%, and chloramphenicol 2.9%. Conclusion In this study, high vertical transmission (mother to neonates) rate was observed. The prevalence of vaginal GBS colonization of women at delivery was 11.9% and significantly associated with the history of prolonged rupture of membranes and urinary tract infections. Gestational age of <37 weeks, low birth weight of <2.5 kg, and maternal history of vaginal discharge were associated with neonatal GBS colonization. Hence, there is a need for antenatal culture-based GBS screening, risk factor-based interventions, and regular follow-up of drug resistance patterns for proper treatment and management of GBS.

Prevalence of Group B Streptococcus Colonization among Pregnant Women and Feto-Maternal Outcomes in a Tertiary Health Institution, North-Western Nigeria

Background: Group B Streptococcus (GBS) infection is a major cause of bacterial infections in the peri-natal period. These include amnionitis, urinary tract infections and endometritis. At birth, 50-60% of the neonates born to colonized mothers have positive cultures taken from mucus membranes and the skin. Aim: The aim of this study is to determine prevalence of GBS colonization and compare the maternal and perinatal outcomes among GBS positive and GBS negative women within 7 days postpartum. Methodology: This was a longitudinal study among pregnant women between 35-37 weeks gestation attending antenatal clinic at Usman Danfodiyo University Teaching Hospital, Sokoto. Vaginal and rectal swabs were taken from the participants and cultured for growth of Group B Streptococcus within 24 hours. The participants were followed up to 7 days post-delivery with their newborns to determine the maternal and early neonatal outcomes. Results: One hundred and eighty five (185) women were recruited and 159 (85.9%) participants were available for follow-up to determining feto-maternal outcomes. Among the participants, 3.8% (7) had GBS vaginal colonization. There was no single case of early neonatal infection, intensive neonatal resuscitation nor neonatal mortality among both GBS positive and GBS negative women. Conclusion: It has been found that the prevalence of maternal GBS colonization during pregnancy was low and neither GBS colonization nor GBS non-colonization was associated with poor maternal or poor fetal outcomes.

Group B Streptococcus vaginal colonization in pregnant women living with HIV infection: prevalence and antibiotic susceptibility at HIV referral centers in Lagos, Nigeria

Objectives Group B Streptococcus (GBS) colonization of the genital tract is often asymptomatic yet associated with increased risks of maternal and neonatal morbidity especially amongst women living with HIV infection. The objectives of this study were to determine the prevalence of GBS colonization of the genital tract in women living with HIV infection and antibiotic susceptibility of GBS in the genital tract. Method This cross-sectional study recruited 244 pregnant women (122 women living with HIV infection and 122 HIV-uninfected women) between 35 and 37 weeks of gestation. GBS colonization was determined by collecting lower vaginal and anal swabs at recruitment. Swabs were cultured in Todd Hewitt’s broth and confirmed by Christie, Atkins, and Munch-Peterson (CAMP) test. Most recent CD4 count and viral load estimates were retrieved from the women’s records. Maternal and neonatal outcomes and antibiotic susceptibility were assessed. Statistical analysis was performed at 95% confidence interval at a statistical significance of p < .005 Results The prevalence of GBS colonization of the genital tract in all participants was 3.3%; GBS was isolated in 4 (3.3%) of 122 pregnant women living with HIV. No woman with a GBS-colonized genital tract developed puerperal sepsis and no neonatal infection occurred in neonates born to GBS-positive women, irrespective of HIV infection status. In women living with HIV, GBS isolate was resistant to Ampicillin (100%), Ceftriaxone (100%), Vancomycin (100%), yet partially sensitive to Ciprofloxacin (50%). Conclusion Pregnant women living with HIV do not have an increased risk of genital GBS colonization. Vaginal GBS colonization was not associated with an adverse perinatal outcome. Antibiotic use for GBS colonization should be based on sensitivity pattern and not empiric.

Polymerase chain reaction for Group B Streptococci (GBS) at labor highly correlates with vaginal GBS load

Objective To explore factors associated with a high vaginal GBS load during labor considering (1) the recto-vaginal GBS load at 35–37 weeks’ gestation determined by culture and (2) the vaginal GBS colonization determined by a polymerase chain reaction (PCR) assay during labor. Methods From an unselected cohort of 902 pregnant women, we obtained (1) recto-vaginal swabs for culture of GBS at 35–37 weeks’ gestation (GBSrectovag-36), (2) vaginal swabs for GBS PCR detection at labor (PCRvag-labor), and (3) vaginal swabs for culture of GBS at labor (GBSvag-labor). The GBS load was classified semi quantitatively according to a culture protocol without prior broth enrichment of the swab samples: none (0), few (+), some (++), or many (+++) GBS colonies. Results Among 902 unselected pregnant women, 859 (95%) had a vaginal swab culture taken at labor, which was classified semi quantitatively. High load GBSvag-labor (+++) were found in 31 participants. GBSrectovag-36 showed a sensitivity of 90% (28/31) and a PPV of 23% (28/121), whereas PCRvag-labor had a sensitivity of 98% (30/31, non-significant difference) and a PPV of 42% (30/71, p < .01). PCR at labor had a lower sensitivity (78%) for detection of vaginal colonization with GBS at labor (any load) compared to recto/vaginal colonization with GBS at 36 weeks (92%). Vaginal colonization with GBS at 36 weeks seemed to have a lower sensitivity for detecting GBS in vagina at labor for high load (48%) and for any load (39%). Conclusion PCR at labor has higher detection rate (non-significant) and PPV in identification of laboring women with a high load of vaginal GBS compared with recto-vaginal culture at 36 weeks’ gestation.

Group B streptococcal colonization in elderly women

BackgroundIn non-pregnant adults, the incidence of invasive Group B Streptococcus (GBS) disease is continuously increasing. Elderly and immunocompromised persons are at increased risk of infection. GBS commonly colonizes the vaginal tract, though data on colonization in the elderly are scarce. It is unknown whether the prevalence of GBS colonization is increasing in parallel to the observed rise of invasive infection. We conducted a three-year (2017–2019) prospective observational cross-sectional study in two teaching hospitals in Switzerland to determine the rate of GBS vaginal colonization in women over 60 years and i) to compare the proportions of known risk factors associated with invasive GBS diseases in colonized versus non-colonized women and ii) to evaluate the presence of GBS clusters with specific phenotypic and genotypic patterns in this population.MethodsGBS screening was performed by using vaginal swabs collected during routine examination from women willing to participate in the study and to complete a questionnaire for risk factors. Isolates were characterized for antibiotic resistance profile, serotype and sequence type (ST).ResultsThe GBS positivity rate in the elderly was 17% (44/255 positive samples), and similar to the one previously reported in pregnant women (around 20%). We could not find any association between participants’ characteristics, previously published risk factors and GBS colonization. All strains were susceptible to penicillin, 22% (8/36) were not susceptible to erythromycin, 14% (5/36) were not susceptible to clindamycin and 8% (3/36) showed inducible clindamycin resistance. Both M and L phenotypes were each detected in one isolate. The most prevalent serotypes were III (33%, 12/36) and V (31%, 11/36). ST1 and ST19 accounted for 11% of isolates each (4/36); ST175 for 8% (3/36); and ST23, ST249 and ST297 for 6% each (2/36). Significantly higher rates of resistance to macrolides and clindamycin were associated with the ST1 genetic background of ST1.ConclusionsOur findings indicate a similar colonization rate for pregnant and elderly women.Trial registrationCurrent Controlled Trial ISRCTN15468519; 06/01/2017

Relationship between vaginal group B streptococcus colonization in the early stage of pregnancy and preterm birth: a retrospective cohort study

BackgroundAlthough infection and inflammation within the genital tract during pregnancy is considered a major risk factor for spontaneous preterm birth (PTB), there are few studies on association between vaginal microorganisms in the early stage of pregnancy and PTB. The aim of this study was to investigate relationship between vaginal Group B streptococcus (GBS) colonization, a leading cause of infection during pregnancy, in the early stage of pregnancy and PTB.MethodsThis single-center, retrospective cohort study utilized data from 2009 to 2017 obtained at TOYOTA Memorial Hospital. Women with singleton pregnancies who underwent vaginal culture around 14 weeks of gestation during their routine prenatal check-up were included. Vaginal sampling for Gram staining and culture was performed regardless of symptoms. GBS colonization was defined as positive for GBS latex agglutination assay. Statistical analysis was performed to determine the factors associated with PTB.ResultsOverall 1079 singleton pregnancies were included. GBS (5.7%) and Candida albicans (5.5%) were the most frequently observed microorganisms. The incidence of PTB (before 34 and before 37 weeks of gestation) were significantly higher in the GBS-positive group than in the GBS-negative group (6.6% vs 0.5%, p = 0.001 and 9.8% vs 4.3%, p = 0.047). Our multivariable logistic regression analysis revealed that GBS colonization was a factor associated with PTB before 34 and before 37 weeks of gestation (Odds ratio [OR] 15.17; 95% confidence interval [CI] 3.73–61.74), and OR 2.42; 95%CI 1.01–5.91, respectively).ConclusionsThe present study found that vaginal GBS colonization in the early stage of pregnancy was associated with PTB. Our study indicates that patients at a high risk for PTB can be extracted by a simple method using conventional culture method.

Vaginal Colonization and Antibiotic Susceptibility Pattern of Group B &amp;lt;i&amp;gt;Streptococcus&amp;lt;/i&amp;gt; Isolated from Pregnant Women in Maternit&amp;#233; de l’H&amp;#244;pital Des Soeurs de Pauvres de Bergame de Kimbanseke, Kinshasa, Democratic Republic of Congo

Group B Streptococcus (GBS) is a Gram-positive bacterium which often colonizes maternal vaginal and rectal epitheliums and can be transmitted to the neonate during delivery. GBS infections may cause significant maternal and neonatal morbidity, including sepsis, pneumonia and meningitis. In Democratic Republic of Congo, few studies have been done on GBS colonization of pregnant women. This study was conducted in Kinshasa, Democratic Republic of Congo in order to determine the prevalence of GBS vaginal colonization among pregnant women at a gestational age of 35 - 37 weeks and the antibiotic susceptibility. Vaginal swabs of 104 pregnant women were inoculated onto Chromatic Strepto B medium. GBS isolates were identified by Gram staining, catalase test, blue-green colonies and confirmed to be GBS by Strepto B latex test kit. Antibiotic susceptibility test was done using the disc diffusion method. The prevalence of GBS vaginal colonization was 23.07%. Of the isolates studied 100%, 75%, 62.5%, 50% were sensitive to vancomycin, clindamycin, cefazolin, and erythromycin respectively. Our findings seem to suggest that maternal GBS colonization rate in this study was higher compared to a previous report from Bukavu in Democratic Republic of Congo. All isolates were found to be sensitive to vancomycin which was the most effective antibiotic for the treatment of GBS infections.

Effect of oral Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 on vaginal Group B Streptococcus colonization and vaginal microbiome in late pregnancy

To explore the effects of intervention with oral probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 on vaginal Group B Streptococcus (GBS) colonization, pregnancy outcome and vaginal microbiome in GBS-positive women in the third trimester of pregnancy. This study were conducted among 155 women in the third trimester of pregnancy with positive results of GBS culture in the Outpatient Department of Zhujiang Hospital from March to November, 2019. After excluding 32 patients who received lactobacillus intervention for less than 2 weeks or underwent postpartum GBS retesting, the women were divided into oral probiotics intervention group (60 cases) and non-intervention group (63 cases). According to the results of GBS retesting, the 60 women in the intervention group were divided into GBS-negative group (18 cases) and persistent GBS-positive group (42 cases). At the end of the intervention, the rates of negative GBS culture result were calculated and the pregnancy outcomes were compared. From 5 women randomly selected from the intervention group, samples of vaginal secretions were collected before and after the intervention for amplicon sequencing and bioinformatics analysis. At the end of the intervention, the GBS-negative rate in the intervention group was 30% (18/60), as compared with 23% (3/13) in the non-intervention group. Probiotic intervention significantly reduced the incidence of premature rupture of membranes (P < 0.05) and reduced the use of antibiotics during pregnancy (P < 0.05). OTU analysis of the vaginal secretions suggested probiotic intervention decreased the total sequence number and GBS sequence number, increased the species composition, and significantly decreased GBS abundance (P < 0.05). Probiotics intervention also significantly decreased the species abundance of Enterococcus, Staphylococcus and Streptococcus in the vaginal flora (P < 0.05). Intervention with oral probiotics can reduce vaginal GBS colonization in late pregnancy and improve the pregnancy outcome. Lactobacillus is capable of reducing the abundance of GBS and other pathogenic bacteria to improve the microbiome of vaginal flora.

English

BACKGROUND Lancefield Group-B Streptococcus (GBS) emerged as a significant neonatal pathogen with mortality rates of 15 - 50 % in western countries during 1970s. In India, incidence of invasive neonatal GBS diseases is around 0.17 per 1000 live birth and probably is underestimated. Hence, the study was undertaken to evaluate the vaginal GBS colonization in pregnant women along with the neonatal outcome. METHODS The study was single centered, hospital based observational cross-sectional study done in the dept. of Obstetrics &amp; Gynaecology at Agartala Government Medical College (AGMC), and GBP Hospital for one &amp; half years (Jan’ 16 - June’ 17). 250 Pregnant mothers with 31 to 40 weeks of gestation with singleton pregnancy, delivering either by Caesarean section &amp; Vaginal delivery, were included in this study. They were recruited from obstetrics OPD and casualty of AGMC &amp; GBP Hospital. During 1 st pelvic examination, two low vaginal swabs were taken for Gram Staining, and for determination of ß-hemolytic colony in blood agar. After identification of GBS from genitalia, outcome of neonates in these positive cases were evaluated for up to 28 days after delivery. RESULTS GBS was found in 8.8 % of total women recruited and was more common in multi-gravida. GBS vaginal colonization was significantly associated with low birth weight, and preterm delivery (p value 0.01) which is significant. CONCLUSIONS Prevalence of vaginal GBS colonization is more in pregnant mothers, more in multigravidas &amp; is associated with low-birth-weight neonates and preterm delivery. So, there is a need to formulate guidelines for incorporation of detection of vaginal colonization in multi gravidas to determine its prevalence. KEYWORDS Group-B Streptococcus (GBS), Multigravidas, Colonization, Neonates, Pregnant Women

Persistence of group B Streptococcus vaginal colonization and prevalence of hypervirulent CC-17 clone correlate with the country of birth: a prospective 3-month follow-up cohort study.

To identify factors associated with vaginal colonization and persistence by group B Streptococcus (GBS) and by the hypervirulent neonatal CC-17 clone in late pregnancy and after delivery, a multicentre prospective observational cohort with 3-month follow-up was established in two university hospitals, Paris area, France. Pregnant women were recruited when antenatal screening for GBS vaginal colonization at 34-38weeks of gestational age was positive. Vaginal samples were analysed by conventional culture methods at antenatal screening, delivery, and 21 and 60days following delivery. Identification of the hypervirulent neonatal GBS CC-17 was performed. Colonization was defined as persistent when all vaginal samples were positive for GBS. A total of 754 women were included. GBS vaginal colonization was persistent in 63% of the cases (95% CI 59%-67%). Persistent colonization was more likely in women born in Sub-Saharan Africa compared with women born in France (OR = 1.88, 95% CI 1.05-3.52), and GBS CC-17 was overrepresented in women born in Sub-Saharan Africa (OR = 2.09, 95% CI 1.20-3.57). Women born in Sub-Saharan Africa are at higher risk for GBS vaginal persistence than women born in France. This observation correlates with an increased prevalence of the hypervirulent GBS CC-17 in the former group, which likely reflect variations linked to ethnicity and vaginal community-state types and might account for the increased susceptibility of black neonates to GBS infections.

T cell response during Group B Streptococcus vaginal colonization and ascending infection

Abstract Pre-term birth, miscarriage, and other adverse pregnancy outcomes remain the primary cause of neonatal death and are associated with bacterial ascending infections within the female reproductive tract. Group B Streptococcus (GBS), a vaginal tract colonizer, is a leading contributor to adverse pregnancy outcomes and neonatal invasive disease. We have developed a mouse model of GBS vaginal colonization and ascending infection and have observed increased IL-17 production in mice that cleared GBS colonization compared to those still colonized. Thus, we hypothesize that IL-17 and IL-17-producing cells may be important for host defense; yet, the immune dynamics during GBS vaginal persistence and ascending infection/adverse pregnancy outcomes remain unknown. T cells are a major source of IL-17 in the mucosa. To assess the role of adaptive immunity during GBS colonization, we colonized RAG1+/+ and RAG1−/− mice with GBS and observed increased persistence of GBS in the vaginal tract of the RAG1−/− mice. To determine the cellular source of IL-17 within the reproductive tract of GBS-colonized mice, we isolated immune cells from vaginal, cervical, and uterine tissues at the time of GBS clearance and performed flow cytometry. TCRɣδ+ cells comprised the highest percentage of RORɣT+ immune cells in the vagina, cervix, and uterus. We further observed an increased percentage of TCRɣδ+ cells in the uterus of GBS-colonized mice compared to naïve mice at day 9 post-inoculation, at which point half the mice had cleared. We hypothesize that IL-17-producing TCRɣδ+ cells contribute to GBS clearance in the murine reproductive tract. Future studies will assess GBS vaginal persistence and ascending infection in IL-17- and TCRɣδ-deficient mouse lines.

Mucosal Vaccination with Lactococcus lactis-Secreting Surface Immunological Protein Induces Humoral and Cellular Immune Protection against Group B Streptococcus in a Murine Model.

Group B Streptococcus (GBS) is the primary etiological agent of sepsis and meningitis in newborns and is associated with premature birth and stillbirth. The development of a licensed vaccine is one of the pending challenges for the World Health Organization. Previously, we showed that oral immunization with surface immune protein (SIP) decreases vaginal colonization of GBS and generates functional opsonizing antibodies, which was determined by opsonophagocytic assays (OPA) in vitro. We also showed that the protein has an adjuvant vaccine profile. Therefore, an oral vaccine based on SIP may be an attractive alternative to employ in the development of new vaccines against GBS. Lactococcus lactis is a highlighted oral vaccine probiotic inducer of the mucosal immune response. This bacterium could serve as an antigen-delivering vehicle for the development of an edible vaccine and has been used in clinical trials. In this study, we showed that an oral vaccine with a recombinant L. lactis strain secreting SIP from GBS (rL. lactis-SIP) can induce protective humoral and cellular immunity in an experimental model of GBS vaginal colonization in C57BL/6 mice. Mice immunized with rL. lactis-SIP were protected against clinical symptoms and bacterial colonization after GBS vaginal colonization. Our rL. lactis-SIP vaccine also induces an increase of immunoglobulin G (IgG) and immunoglobulin A (IgA) specifically against SIP. The adoptive transfer of serum from vaccinated mice to naïve mice generated protection against GBS vaginal colonization. Moreover, the rL. lactis-SIP strain induces the activation of SIP-specific T cells, which could decrease GBS vaginal colonization and generate protective antibodies when transferred to other mice. Our experimental observations strongly support the notion that rL. lactis-SIP induces protective humoral and cellular immunity and could be considered as a novel alternative in the development of vaccines for GBS.

Group B Streptococcus serotypes Ia and V induce differential vaginal immune responses that may contribute to long term colonization of the female reproductive tract.

Group B Streptococcus (GBS) is a common colonizer of the female genital tract at the time of pregnancy and has been associated with severe neonatal infections. Despite trials for GBS vaccines already being underway, the factors influencing vaginal GBS colonization and clearance are currently poorly understood. Within this study, we investigated the host immune responses to GBS infections in mice that affect GBS vaginal colonization and clearance. Cervicovaginal swabs were used to measure vaginal GBS persistence, and vaginal cytokine responses were measured using the BioPlex® system. Lymphocytes isolated from spleens were stimulated with UV-killed GBS to examine systemic cellular responses. Additional in vitro cellular experiments using human vaginal epithelial cells were also performed, examining the effect pregnancy level hormones had on GBS adhesion, invasion, and cytokine responses. We observed significant differences in the ability of GBS serotype V infections to persist, compared with GBS serotype Ia vaginal infections. Vaginal cytokine response examination identified temporal changes in cytokine production (IL10, IFNγ, IL6, IL1β, and TNFα) in relation to GBS serotype and clearance or colonization. Lymphocyte proliferation assays also revealed robust cellular immune responses to GBS vaginal infections irrespective of clearance or colonization. In vitro human cellular analyses also identified that vaginal epithelial cell line cytokine production was suppressed in the presence of hormones despite no alteration in adhesion/invasion. Here, we establish previously unknown, serotype specific, temporal immune responses which may be associated with vaginal GBS colonization or clearance in the female genital tract.

Association between Colonization with Group B Streptococcus and Preterm Delivery

Background: Despite major advances in perinatal care, preterm delivery (PTL) is still the predominant cause of perinatal mortality and a major cause of neurological morbidity in surviving infants. Objective: the objective of this study is to find any association between maternal group B streptococcus (GBS) colonization and preterm delivery. Patients and Method: This study is a prospective study including 100 pregnant women between 28 – 36 weeks of gestation from those who attended the Emergency Department at Al-Galaa Maternity Teaching Hospital from April 2015 to August 2015. All patients were tested for genital colonization with Group B streptococcus (GBS) by taking low vaginal swab that was sent for microbiological examination. Results: In this study there was a significant difference between positive and negative cases as regard obstetric data. As regard preterm labor, 80% of positive swab cases had preterm labor compared to 46.2% of negative swab cases and this was statistically significant. Positive vaginal swab cases are at 7 times higher risk to have preterm labor compared to negative cases. Conclusion: GBS vaginal colonization was associated with premature labour in the studied population. Women with GBS vaginal colonization qualify for intrapartum chemoprophylaxis. The study results suggest that the early prenatal screening for GBS may identify pregnant women at risk of PTL.

Cas9 Contributes to Group B Streptococcal Colonization and Disease.

Group B Streptococcus (GBS) is a major opportunistic pathogen in certain adult populations, including pregnant women, and remains a leading etiologic agent of newborn disease. During pregnancy, GBS asymptomatically colonizes the vaginal tract of 20–30% of healthy women, but can be transmitted to the neonate in utero or during birth resulting in neonatal pneumonia, sepsis, meningitis, and subsequently 10–15% mortality regardless of antibiotic treatment. While various GBS virulence factors have been implicated in vaginal colonization and invasive disease, the regulation of many of these factors remains unclear. Recently, CRISPR-associated protein-9 (Cas9), an endonuclease known for its role in CRISPR/Cas immunity, has also been observed to modulate virulence in a number of bacterial pathogens. However, the role of Cas9 in GBS colonization and disease pathogenesis has not been well-studied. We performed allelic replacement of cas9 in GBS human clinical isolates of the hypervirulent sequence-type 17 strain lineage to generate isogenic Δcas9 mutants. Compared to parental strains, Δcas9 mutants were attenuated in murine models of hematogenous meningitis and vaginal colonization and exhibited significantly decreased invasion of human brain endothelium and adherence to vaginal epithelium. To determine if Cas9 alters transcription in GBS, we performed RNA-Seq analysis and found that 353 genes (>17% of the GBS genome) were differentially expressed between the parental WT and Δcas9 mutant strain. Significantly dysregulated genes included those encoding predicted virulence factors, metabolic factors, two-component systems (TCS), and factors important for cell wall formation. These findings were confirmed by qRT-PCR and suggest that Cas9 may regulate a significant portion of the GBS genome. We studied one of the TCS regulators, CiaR, that was significantly downregulated in the Δcas9 mutant strain. RNA-Seq analysis of the WT and ΔciaR strains demonstrated that almost all CiaR-regulated genes were also significantly regulated by Cas9, suggesting that Cas9 may modulate GBS gene expression through other regulators. Further we show that CiaR contributes to GBS vaginal colonization and persistence. Altogether, these data highlight the potential complexity and importance of the non-canonical function of Cas9 in GBS colonization and disease.