Vaginal Group B Streptococcus Research Articles

Diet influences community dynamics following vaginal group B streptococcus colonization.

The vaginal microbiota plays a pivotal role in reproductive, sexual, and perinatal health and disease. Unlike the well-established connections between diet, metabolism, and the intestinal microbiota, parallel mechanisms influencing the vaginal microbiota and pathogen colonization remain overlooked. In this study, we combine a mouse model of Streptococcus agalactiae strain COH1 [group B Streptococcus (GBS)] vaginal colonization with a mouse model of pubertal-onset obesity to assess diet as a determinant of vaginal microbiota composition and its role in colonization resistance. We leveraged culture-dependent assessment of GBS clearance and culture-independent, sequencing-based reconstruction of the vaginal microbiota in relation to diet, obesity, glucose tolerance, and microbial dynamics across time scales. Our findings demonstrate that excessive body weight gain and glucose intolerance are not associated with vaginal GBS density or timing of clearance. Diets high in fat and low in soluble fiber are associated with vaginal GBS persistence, and changes in vaginal microbiota structure and composition due to diet contribute to GBS clearance patterns in nonpregnant mice. These findings underscore a critical need for studies on diet as a key determinant of vaginal microbiota composition and its relevance to reproductive and perinatal outcomes.IMPORTANCEThis work sheds light on diet as a key determinant influencing the composition of vaginal microbiota and its involvement in group B Streptococcus (GBS) colonization in a mouse model. This study shows that mice fed diets with different nutritional composition display differences in GBS density and timing of clearance in the female reproductive tract. These findings are particularly significant given clear links between GBS and adverse reproductive and neonatal outcomes, advancing our understanding by identifying critical connections between dietary components, factors originating from the intestinal tract, vaginal microbiota, and reproductive outcomes.

Vaginal microbial dynamics and pathogen colonization in a humanized microbiota mouse model

Vaginal microbial composition is associated with differential risk of urogenital infection. Although Lactobacillus spp. are thought to confer protection against infection, the lack of in vivo models resembling the human vaginal microbiota remains a prominent barrier to mechanistic discovery. Using 16S rRNA amplicon sequencing of C57BL/6J female mice, we found that vaginal microbial composition varies within and between colonies across three vivaria. Noting vaginal microbial plasticity in conventional mice, we assessed the vaginal microbiome of humanized microbiota mice (HMbmice). Like the community structure in conventional mice, HMbmice vaginal microbiota clustered into community state types but, uniquely, HMbmice communities were frequently dominated by Lactobacillus or Enterobacteriaceae. Compared to conventional mice, HMbmice were less susceptible to uterine ascension by urogenital pathobionts group B Streptococcus (GBS) and Prevotella bivia. Although Escherichia and Lactobacillus both correlated with the absence of uterine GBS, vaginal pre-inoculation with exogenous HMbmouse-derived E. coli, but not Ligilactobacillus murinus, reduced vaginal GBS burden. Overall, HMbmice serve as a useful model to elucidate the role of endogenous microbes in conferring protection against urogenital pathogens.

Prevalence of positive group B streptococcal infections among pregnant women in Najran, Saudi Arabia

Background: Group B streptococcus (GBS) is the most common bacterium to infect women during pregnancy, and vaginal GBS colonisation is a risk factor for newborn GBS illness. The presence of GBS in the woman during labour is thought to be accurately predicted by GBS detection in the final five weeks before to delivery. This study aimed to assess the prevalence of GBS genital infections among pregnant women in Najran, Saudi Arabia. Methods: This cross-sectional retrospective study was conducted at the Armed Forces Hospital in Saudi Arabia. The study included data from electronic health records of all pregnant women who were examined and tested for genitourinary GBS infection in the hospital. Data was retrieved using a pre-designed form that included characteristic of the pregnant women, the gestational age at the time of GBS testing, and swap result of GBS. For each positive GBS swap, the antibiotic sensitivity against twenty-one antibiotics was recorded. Results: A total of 2308 pregnant women were included. The mean age was 32±7 years. The prevalence of positive GBS swap was 10.4%. The average gestational age of the women who had a positive swap was 34±9 weeks. Regarding antibiotics sensitivity, Penicillin (86.7%), Ampicillin (61.8%) and cephalexin (55.6%) were among the antibiotics that showed the highest sensitivity rates. Conclusions: We found an isolation rate of 10.4% of GBS among pregnant women who attended Najran Armed Forces Hospital. We recommend more comprehensive screening programs and strict management plans to avoid antimicrobial resistance to spread among these GBS strains.

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.

Exploring the Feasibility of Intrapartum GBS Collection to Identify Residual GBS in a Pilot Study of an Antenatal Probiotic Intervention

(1) Background: We aimed to explore the feasibility of collecting intrapartum maternal Group B Streptococcus (GBS) colonization and immediate post-birth neonatal GBS colonization cultures for use in a larger trial and to identify cases of residual GBS, which were hypothesized to be less common in the probiotics group. (2) Methods: This sub-study added additional outcome measures to the parent study to identify intrapartum and neonatal colonization and compare between probiotic and placebo groups and to identify cases of residual GBS. Intrapartum maternal vaginal and rectal GBS cultures were collected at the time of admission to a hospital for labor and to give birth. Neonatal oral and nasopharynx GBS cultures were collected within 1–2 h of giving birth. (3) Results: Thirty intrapartum samples were collected; twenty-eight had complete data. The antepartum GBS results significantly predicted the intrapartum results (p = 0.005), with 86.7% of cultures remaining the same at both time points. There were four cases where the intrapartum GBS results were different to the 36-week antepartum cultures results. A case of residual GBS was identified in one probiotic group participant. None of the neonatal swabs were positive for GBS. No cases of EOGBSD occurred in infants born to the study participants. (4) Conclusions: Although the 36–37 week GBS results significantly predicted the intrapartum results, the utility for a larger research trial on probiotics to reduce antenatal GBS is unclear. Intrapartum GBS swab collection was feasible in a busy nurse, midwife, and physician practice. GBS was not recovered from neonatal oral and nasopharyngeal swabs. The pathways of neonatal GBS colonization require further study.

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.

Vaginal Carriage of Group B Streptococcus (GBS) in Pregnant Women, Antibiotic Sensitivity and Associated Risk Factors in Dakar, Senegal.

The eradication of neonatal Group B Streptococcus (GBS) infections, considered as a major public health priority, necessarily requires a mastery of the data on vaginal carriage in pregnant women. The aims of this study were to determine the prevalence of vaginal carriage of GBS in pregnant women, antibiotic susceptibility, and associated risk factors. This was a cross-sectional, descriptive study conducted over a period of 9 months (July 2020 to March 2021) in pregnant women between 34 and 38 weeks of gestation (WG) followed at the Nabil Choucair health center in Dakar. Identification and antibiotic susceptibility of GBS isolates were performed on the Vitek 2 from vaginal swabs cultured on Granada medium. Demographic and obstetric interview data were collected and analyzed on SPSS (version 25). The level of significance for all statistical tests was set at P < .05. The search of GBS vaginal carriage had involved 279 women aged 16 to 46 years, with a median pregnancy age of 34 (34-37) weeks' gestation. GBS was found in 43 women, for a vaginal carriage rate of 15.4%. In 27.9% (12/43) of volunteers screened, this carriage was monomicrobial, while in 72.1% (31/43) of women, GBS was associated with other pathogens such as Candida spp. (60.5%), Trichomonas vaginalis (2.3%), Gardnerella vaginalis (34.9%) and/or Mobiluncus spp. (11.6%). The level of resistance was 27.9% (12/43) for penicillin G, 53.5% (23/43) for erythromycin, 25.6% (11/43) for clindamycin and 100% for tetracycline. However, the strains had retained fully susceptible to vancomycin and teicoplanin. The main risk factor associated with maternal GBS carriage were ectocervical inflammation associated with contact bleeding (OR = 3.55; P = .005). The high rate of maternal vaginal GBS carriage and the levels of resistance to the various antibiotics tested confirm the importance of continuous GBS surveillance in our resource-limited countries.

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.

Correlation Between B Group Streptococcus Infection in Vagina and Maternal Serum Procalcitonin Level with Preterm Delivery

Preterm delivery is one of the biggest contributors to neonatal death because the organ systems in premature babies are not yet fully developed. The cause of preterm labor is multifactorial, one of which is complex inflammation due to Group B Streptococcus (GBS) bacterial infection. Maternal serum procalcitonin is a prohormone involved in the inflammatory process, and specifically as a marker of bacterial infection. This study time to determine the relationship between vaginal GBS bacterial infection and high maternal serum procalcitonin levels in preterm labor. This study used a cross-sectional method. Samples were 31 pregnant women who came to the Obstetrics ER at Sanglah Hospital Denpasar with a diagnosis of preterm delivery that met the inclusion criteria. Vaginal mucus samples were examined at the Clinical Microbiology Laboratory of Sanglah Hospital and procalcitonin samples were examined at the Clinical Pathology Laboratory of Sanglah Hospital. Descriptive and analytical analysis was performed on the data obtained. There were 7 positive GBS results (22.5%) and 24 negative GBS results (77.5%). The results of high procalcitonin obtained 12 (38.7%) while the normal 19 (61.3%). In the Chi-Square test, the PR value was 3.4 (95% CI: 1.61-7.30) with p value = 0.004. Therefore, it can be concluded that there is a relationship between GBS infection and serum procalcitonin levels, where positive GBS infection is a risk factor that increases the occurrence of high serum procalcitonin levels in preterm labor.

Prevalence and Risk Factors of Group B Streptococcus Colonization in Pregnant Women: A Pilot Study in Palestine.

Background Maternal Streptococcus agalactiae (Group B Streptococcus (GBS)) colonization is an important cause of complications in mothers and neonates during gestation and after delivery. The data regarding GBS colonization among pregnant women in Palestine is scarce. The aim of this study is to determine the prevalence of GBS colonization, its associated risk factors, and the antibiotic sensitivity patterns in Nablus, West Bank, Palestine. Methods A cross-sectional, single center study conducted at Rafidia Governmental Hospital in Nablus, West Bank, Palestine. Samples were collected between November 2019 and January 2020. Vaginal swabs from 200 pregnant women (≥35 weeks of gestation) attending the labor and delivery department were plated directly on CHROMagarTM StrepB (CHROM agar, France) and placed in an incubator at 35–37°C. After 24 and 48 hours, the plates were checked for growth and classified into three categories: growth of GBS with mauve colonies on chromogenic media, no growth, or other growth. The identification of the mauve colonies was confirmed by the CAMP test. Identified GBS isolates were tested for susceptibility to vancomycin, ampicillin, clindamycin, cefotaxime, erythromycin, and levofloxacin using the disc diffusion method. Clinical and demographic information were collected using a questionnaire. Result The overall prevalence of GBS colonization was 12%. The median age of the study population was 27 years. GBS colonization was significantly associated with age (p=0.013), history of previous preterm delivery (p=0.013), and parity (p=0.015). No association was noted with smoking, previous abortion, previous history of fetal demise, vaginitis, or urinary tract infection. Resistance to ampicillin, vancomycin, cefotaxime, erythromycin, clindamycin, and levofloxacin was found to be 91.7%, 54.2%, 45.8%, 29.2%, 25%, and 8.3%, respectively. Conclusion The prevalence of vaginal GBS in this study was 12% from Nablus, West Bank. Further research is needed to determine the GBS serotypes common in West Bank and the burden they cause on the health system. Moreover, this study also highlights the need to establish a screening program suited to a developing country with low control on the antibiotic's prescription protocols.

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.

PREVALENCE OF GROUP B STREPTOCOCCUS AND LEVEL OF RELIGIOSITY OF JEWISH MOTHERS IN NORTHERN ISRAEL - IS THERE A CONNECTION?

Group B streptococcus (GBS) during pregnancy is associated with increased risk of preterm delivery and is a leading cause of invasive infections in newborns. Rates of vaginal GBS prevalence in pregnant women vary among ethnic groups and geographical regions, with a range of 0.5-38%. The aim is to assess the prevalence rate of GBS bacteria among Jewish pregnant mothers in northern Israel, according to their level of religiosity. A cross-sectional study was pursued in 303 Jewish mothers at Ziv Medical Center, Safed of whom 89 (29.4%) were secular, 59 (19.5%) traditional, 60 (19.8%) Orthodox and 95 (31.3%) ultra-Orthodox, from December 2019-July 2020. All participants were tested for GBS from pregnancy week 35 as part of the routine medical care at their Health Maintenance Organization (HMO) and submitted the GBS test result upon arrival at the hospital delivery room. The overall prevalence of GBS was 33.7%: 16.9% of the secular mothers, 25.4% of the traditional women and 46.5% of the Orthodox and ultra-Orthodox group (p&lt;0.001). In a univariate regression model the risk of GBS carriage in Orthodox mothers was 2.5 times higher and 6 times higher in ultra-Orthodox mothers than in secular mothers (p for trend &lt;0.001). The prevalence of GBS was directly and significantly associated with the level of the birthing mother's religiosity. This study shows the need for systematic GBS screening of all pregnant women, particularly of Orthodox and ultra-Orthodox women, prior to their arrival in the delivery room.

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.

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.

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

Improvement of selection of pregnant women for intrapartum polymerase chain reaction screening for vaginal Group B Streptococci (GBS) colonization by adding GBS urine screening at 35-37 weeks of pregnancy.

To evaluate whether systematic antepartum screening for Group B Streptococci (GBS) by urine culture improves the risk factor-based selection of pregnant women for intrapartum GBS screening with a rapid polymerase chain reaction (PCR) assay. A prospective observational study was conducted between April 2013 and June 2014. GBS colonization judged by urine culture at 35-37weeks of gestation was compared with the result of a vaginal GBS PCR test at labor as outcome. The results of urine culture were used as exposure variable. The PCR test was performed on intrapartum vaginal samples. Screening for urine GBS in 902 unselected pregnant Danish women at 35-37weeks of gestation predicted intrapartum PCR GBS status with a sensitivity of 33.6%. A positive predictive value of 41.2% was seen among women with low GBS counts (<104CFU/mL) and 83.3% among women with high GBS counts (≥104CFU/mL). Systematic GBS screening of urine at 35-37weeks of gestation added 30.9% extra women for intrapartum GBS PCR screening in the study group. Systematic antepartum GBS screening of urine should be implemented in order to improve risk stratification for early onset GBS by offering laboring women an intrapartum GBS PCR test.

Determinants of Group B streptococcal virulence potential amongst vaginal clinical isolates from pregnant women.

Streptococcus agalactiae, also known as Group B Streptococcus (GBS), is a Gram-positive bacterium isolated from the vaginal tract of approximately 25% of women. GBS colonization of the female reproductive tract is of particular concern during pregnancy as the bacteria can invade gestational tissues or be transmitted to the newborn during passage through the birth canal. Infection of the neonate can result in life-threatening pneumonia, sepsis and meningitis. Thus, surveillance of GBS strains and corresponding virulence potential during colonization is warranted. Here we describe a panel of GBS isolates from the vaginal tracts of a cohort of pregnant women in Michigan, USA. We determined that capsular serotypes III and V were the most abundant across the strain panel, with only one isolate belonging to serotype IV. Further, 12.8% of strains belonged to the hyper-virulent serotype III, sequence type 17 (ST-17) and 15.4% expressed the serine rich repeat glycoprotein-encoding gene srr2. Functional assessment of the colonizing isolates revealed that almost all strains exhibited some level of β-hemolytic activity and that ST-17 strains, which express Srr2, exhibited increased bacterial adherence to vaginal epithelium. Finally, analysis of strain antibiotic susceptibility revealed the presence of antibiotic resistance to penicillin (15.4%), clindamycin (30.8%), erythromycin (43.6%), vancomycin (30.8%), and tetracycline (94.9%), which has significant implications for treatment options. Collectively, these data provide important information on vaginal GBS carriage isolate virulence potential and highlight the value of continued surveillance.

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.