Stillbirth With Group B Streptococcus Disease Worldwide: Systematic Review and Meta-analyses

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.

Antibody kinetics between birth and three months of life in healthy infants with natural exposure to Group B streptococcus: A UK cohort study

INTRODUCTION

Capsular polysaccharide (CPS) serotype-specific Immunoglobulin G (IgG) in cord blood has been proposed as a correlate of protection against invasive Group B Streptococcus (iGBS) disease. Although protective levels are required in infants throughout the window of vulnerability up to 3 months of age, little is known regarding the kinetics of GBS-specific IgG over this period.

METHODS

We enrolled 33 healthy infants born to mothers colonized with GBS. We collected cord blood and infant blood samples either at one (21-35 days), two (49-63 days), or three months of age (77-91 days). We measured GBS serotype-specific CPS IgG concentrations and calculated the decay rate using a mixed-effects model. We further explored whether the antibody kinetics were affected by common maternal and infant factors and estimated the correlation between IgG concentration at birth and one, two, and three months of age.

RESULTS

The half-life estimate of IgG concentration for homologous and non-homologous GBS serotypes in paired samples with detectable IgG levels at both time points was 27.4 (95 % CI: 23.5-32.9) days. The decay rate did not vary by maternal age (p = 0.7), ethnicity (p = 0.1), gravida (p = 0.1), gestation (p = 0.7), and infant sex (p = 0.1). Predicted IgG titres above the assay lower limit of quantification on day 30 strongly correlated with titres at birth (Spearman correlation coefficient 0.71 [95 % CI: 0.60-0.80]).

CONCLUSION

Our results provide a basis for future investigations into the use of antibody kinetics in defining a serocorrelate of protection against late-onset iGBS disease.

Intrapartum antibiotic prophylaxis selects for mutators in group B streptococci among persistently colonized patients

Through vaginal colonization, GBS causes severe pregnancy outcomes including neonatal sepsis and meningitis. Although intrapartum antibiotic prophylaxis (IAP) has reduced early-onset disease rates, persistent GBS colonization has been observed in patients following prophylaxis. To determine whether IAP selects for genomic signatures that enhance GBS survival and persistence in the vaginal tract, whole-genome sequencing was performed on 97 isolates from 58 patients before (prenatal) and after (postpartum) IAP/childbirth. Core-gene mutation analysis identified 7,025 mutations between the paired isolates. Three postpartum isolates accounted for 98% of mutations and were classified as "mutators" because of point mutations within DNA repair systems. In vitro assays revealed stronger biofilms in two mutators. These findings suggest that antibiotics select for mutations that promote survival in vivo, which increases the likelihood of transmission to neonates. They also demonstrate how mutators can provide a reservoir of beneficial mutations that enhance fitness and genetic diversity in the GBS population.

Comparative Analysis of Microbial Species and Multidrug Resistance Patterns Associated with Lower Urinary Tract Infections in Preterm and Full-Term Births

The rise of multidrug-resistant organisms has significantly complicated the clinical management of urinary tract infections (UTIs), particularly in the context of pregnancy. This study aimed to identify and analyze the significant differences in microbial species and multidrug resistance patterns associated with UTIs in preterm versus full-term births, determine the bacterial species significantly associated with preterm birth, and describe the antibiotic resistance patterns affecting pregnant women with UTIs. This case-control study was conducted in western Romania and focused on pregnant women with UTIs admitted from 2019 to 2023. Data were retrospectively collected from 308 patients with positive cultures. Statistical analyses, including the Chi-square test, Fisher's exact test, and logistic regression models, were employed to compare the proportions of microbial species and resistance patterns between preterm (n = 126) and full-term (n = 182) birth groups and identify factors independently associated with preterm birth. The study found no significant differences in demographic or lifestyle factors between the groups. However, significant differences were observed in several infection and inflammation markers. The median white blood cell count was higher in the preterm group (12.3 vs. 9.1, p = 0.032), and the median C-reactive protein level was significantly higher in the preterm group (18 vs. 7, p < 0.001). The preterm group exhibited a higher incidence of multidrug-resistant organisms, notably ESBL-producing organisms (19.8% vs. 4.4%, p < 0.001) and carbapenem-resistant Enterobacteriaceae (4.8% with p = 0.003). Notably, the resistance to amoxicillin was significantly higher in the preterm group (20.6% vs. 6.6%, p < 0.001). Significant bacterial associations with preterm births included Group B Streptococcus (OR 2.5, p = 0.001) and Enterobacter spp. (OR 1.8, p = 0.022). The study confirmed significant differences in microbial species and multidrug resistance patterns between UTIs associated with preterm and full-term births. The higher prevalence of certain bacteria and increased resistance to commonly used antibiotics in the preterm group underscore the need for tailored antimicrobial therapies and robust microbial identification in managing UTIs during pregnancy.

Spatial profiling of the placental chorioamniotic membranes reveals upregulation of immune checkpoint proteins during Group B Streptococcus infection in a nonhuman primate model

Background

Preterm birth is a leading cause of neonatal mortality, which is often complicated by intrauterine infection and inflammation. We have established a nonhuman primate model of Group B Streptococcus (GBS, Streptococcus agalactiae) infection-associated preterm birth. Immune checkpoints are modulators of the immune response by activating or suppressing leukocyte function and are understudied in preterm birth. The objective of this study was to spatially profile changes in immune protein expression at the maternal-fetal interface during a GBS infection with a focus on immune checkpoints.

Methods

Twelve nonhuman primates (pigtail macaques, Macaca nemestrina) received a choriodecidual inoculation of either: 1) 1-5 X 108 colony forming units (CFU) of hyperhemolytic/hypervirulent GBS (GBSΔcovR, N=4); 2) an isogenic/nonpigmented strain (GBS ΔcovRΔcylE, N=4); or, 3) saline (N=4). A Cesarean section was performed at preterm labor or 3 days after GBS infection or 7 days after saline inoculation. Nanostring GeoMx® Digital Spatial Profiling technology was used to segment protein expression within the amnion, chorion, and maternal decidua at the inoculation site using an immuno-oncology panel targeting 56 immunoproteins enriched in stimulatory and inhibitory immune checkpoint proteins or their protein ligands. Statistical analysis included R studio, Kruskal-Wallis, Pearson and Spearman tests.

Results

Both inhibitory and stimulatory immune checkpoint proteins were significantly upregulated within the chorioamniotic membranes and decidua (VISTA, LAG3, PD-1, CD40, GITR), as well as their ligands (PD-L1, PD-L2, CD40L; all p<0.05). Immunostaining for VISTA revealed positive (VISTA+) cells, predominantly in the chorion and decidua. There were strong correlations between VISTA and amniotic fluid concentrations of IL-1β, IL-6, IL-8, and TNF-α (all p<0.05), as well as maternal placental histopathology scores (p<0.05).

Conclusion

Differential regulation of multiple immune checkpoint proteins in the decidua at the site of a GBS infection indicates a major perturbation in immunologic homeostasis that could benefit the host by restricting immune-driven pathologies or the pathogen by limiting immune surveillance. Protein expression of VISTA, an inhibitory immune checkpoint, was upregulated in the chorion and decidua after GBS infection. Investigating the impact of innate immune cell expression of inhibitory immune checkpoints may reveal new insights into placental host-pathogen interactions at the maternal-fetal interface.

Colonisation of Group B Streptococcus and its effects on pregnancy outcomes in pregnant women in Guangzhou, China: a retrospective study

OBJECTIVES

This study was to investigate the colonisation rate of Group B Streptococcus (GBS) during pregnancy, and to evaluate the influence of GBS colonisation on pregnancy outcomes.

DESIGN

A retrospective cohort study.

SETTING

Data of 47 380 pregnant women from 2016 to 2022 were collected from the Maternal and Child Health Hospital of Huadu District, Guangzhou City, China.

PARTICIPANTS

A total of 15 040 pregnant women were eligible for this study, of which 32 340 were excluded due to non-native pregnant women, in vitro fertilization infants, malformed fetuses, habitual abortion, abortions due to poor reproductive or obstetrical history, artificial insemination, umbilical cord torsion, and other diseases during pregnancy.

PRIMARY OUTCOME MEASURES

The incidence rates of GBS colonisation and premature delivery, fetal distress, premature rupture of membranes (PROM), low birth weight (LBW), abortion and stillbirth.

RESULTS

Of the 15 040 pregnant women included in this study, 1445 developed GBS colonisation, with a prevalence of 9.61% (95% CI, 9.15 to 10.09). Advanced maternal age (≥35 years) predisposed women to GBS colonisation, and the occurrence of GBS colonisation varied among different ethnic groups. Our data revealed that fetal distress, PROM and LBW were more common in pregnant women colonised with GBS than in pregnant women not colonised with GBS. The incidence for premature delivery, fetal distress, PROM and LBW in infants of pregnant women colonised with GBS was 41.0% (OR=1.410, 95% CI, 1.134 to 1.753), 282.5% (OR=3.825, 95% CI, 3.185 to 4.593), 14.9% (OR=1.149, 95% CI, 1.005 to 1.313), and 29.7% (OR=1.297, 95% CI, 1.010 to 1.664), respectively.

CONCLUSIONS

GBS colonisation was relatively low in pregnant women in Guangzhou. Women of advanced maternal age were more prone to GBS colonisation, and pregnant women colonised with GBS were more predisposed to fetal distress, PROM and LBW.

Vaccine value profile for Group B streptococcus

Group B streptococcus (GBS) is a major global cause of neonatal meningitis, sepsis and pneumonia, with an estimated 91,000 infant deaths per year and an additional 46,000 stillbirths. GBS infection in pregnancy is also associated with adverse maternal outcomes and preterm births. As such, the World Health Organization (WHO) prioritised the development of a GBS vaccine suitable for use in pregnant women and use in LMICs, where the burden of disease is highest. Several GBS vaccines are in clinical development. The WHO Defeating Meningitis by 2030 has set a target of 2026 for vaccine licensure. This 'Vaccine Value Profile' (VVP) for GBS is intended to provide a high-level, holistic assessment of the information and data that are currently available to inform the potential public health, economic and societal value of pipeline vaccines and vaccine-like products. This VVP was developed by a working group of subject matter experts from academia, non-profit organizations, public private partnerships and multi-lateral organizations, and in collaboration with stakeholders from the WHO regions of AFR, AMR, EUR, WPR. All contributors have extensive expertise on various elements of the GBS VVP and collectively aimed to identify current research and knowledge gaps. The VVP was developed using only existing and publicly available information.

Identification of a DNA-cytosine methyltransferase that impacts global transcription to promote group B streptococcal vaginal colonization

Group B Streptococcus (GBS) colonizes the female reproductive tract (FRT) and causes adverse pregnancy outcomes and invasive disease following vertical transmission to the fetus or newborn. Despite this major public health burden, the mechanisms of GBS FRT colonization are understudied. A recent transposon sequencing screen identified GBS factors contributing to vaginal colonization and ascending spread, including a putative DNA-cytosine methyltransferase (Dcm). We constructed a Δdcm deletion strain and confirmed that dcm contributes to murine FRT colonization. Investigation of the evolutionary origin of the dcm gene reveals that it is widely distributed across GBS and is encoded as part of a prophage genome that displays evidence of horizontal transfer between GBS strains. We further show that Dcm contributes to 5mC methylation and global regulation of genes involved in carbohydrate metabolism, transcription regulation, and known adhesins and metabolic factors involved in GBS colonization. Interestingly, GBS genes that are induced in the presence of the highly glycosylated vaginal mucin MUC5B were significantly downregulated in the ∆dcm mutant. Furthermore, the ∆dcm mutant exhibited reduced binding to immobilized mucin and was attenuated in its ability to grow on numerous carbon sources including the carbohydrates found on mucins. While the ∆dcm mutant displayed enhanced clearance from the FRT in wild-type mice, there was no significant difference in MUC5B -/- mice, indicating that Dcm-mediated regulation requires MUC5B to promote GBS colonization. This is the first report to characterize the impact of a DNA methyltransferase on GBS gene regulation and FRT colonization. IMPORTANCE Group B Streptococcus (GBS) colonizes the female reproductive tract (FRT) in one-third of women, and carriage leads to numerous adverse pregnancy outcomes including the preterm premature rupture of membranes, chorioamnionitis, and stillbirth. The presence of GBS in the FRT during pregnancy is also the largest predisposing factor for the transmission of GBS and invasive neonatal diseases, including pneumonia, sepsis, and meningitis. The factors contributing to GBS colonization are still being elucidated. Here, we show for the first time that GBS transcription is regulated by an orphan DNA cytosine methyltransferase (Dcm). Many GBS factors are regulated by Dcm, especially those involved in carbohydrate transport and metabolism. We show that GBS persistence in the FRT is dependent on the catabolism of sugars found on the vaginal mucin MUC5B. Collectively, this work highlights the regulatory importance of a DNA methyltransferase and identifies both host and bacterial factors required for GBS colonization.

The Utility of Human Milk Oligosaccharides against Group B Streptococcus Infections of Reproductive Tissues and Cognate Adverse Pregnancy Outcomes

Preterm birth affects nearly 10% of all pregnancies in the United States, with 40% of those due, in part, to infections. Streptococcus agalactiae (Group B Streptococcus, GBS) is one of the most common perinatal pathogens responsible for these infections. Current therapeutic techniques aimed to ameliorate invasive GBS infections are less than desirable and can result in complications in both the neonate and the mother. To this end, the need for novel therapeutic options is urgent. Human milk oligosaccharides (HMOs), an integral component of human breast milk, have been previously shown to possess antiadhesive and antimicrobial properties. To interrogate these characteristics, we examined HMO-mediated outcomes in both in vivo and ex vivo models of GBS infection utilizing a murine model of ascending GBS infection, an EpiVaginal human organoid tissue model, and ex vivo human gestational membranes. Supplementation of HMOs resulted in diminished adverse pregnancy outcomes, decreased GBS adherence to gestational tissues, decreased colonization within the reproductive tract, and reduced proinflammatory immune responses to GBS infection. Taken together, these results highlight the potential of HMOs as promising therapeutic interventions in perinatal health.

Stillbirths and Neonatal Deaths Caused by Group B Streptococcus in Africa and South Asia Identified Through Child Health and Mortality Prevention Surveillance (CHAMPS)

Background

Invasive Group B Streptococcus (GBS) is a common cause of early-onset neonatal sepsis and is also associated with stillbirth. This study aimed to determine the proportion of stillborn infants and infants who died between 0 and 90 days attributable to GBS using postmortem minimally invasive tissue sampling (MITS) in 7 low- and middle-income countries (LMICs) participating in Child Health and Mortality Prevention Surveillance (CHAMPS).

Methods

Deaths that occurred between December 2016 and December 2021 were investigated with MITS, including culture for bacteria of blood and cerebrospinal fluid (CSF), multipathogen polymerase chain reaction on blood, CSF, and lung tissue and histopathology of lung, liver, and brain. Data collection included clinical record review and verbal autopsy. Expert panels reviewed all information and assigned causes of death.

Results

We evaluated 2966 deaths, including stillborn infants (n = 1322), infants who died during first day of life (0 to <24 hours, n = 597), early neonatal deaths (END) (1 day to <7 days; END; n = 593), and deaths from 7 to 90 days (n = 454). Group B Streptococcus was determined to be in the causal pathway of death for 2.7% of infants (79 of 2, 966; range, 0.3% in Sierra Leone to 7.2% in South Africa), including 2.3% (31 of 1322) of stillbirths, 4.7% (28 of 597) 0 to <24 hours, 1.9% (11 of 593) END, and 2.0% (9 of 454) of deaths from 7 to 90 days of age. Among deaths attributed to GBS with birth weight data available, 61.9% (39 of 63) of decedents weighed <2500 grams at birth. Group B Streptococcus sepsis was the postmortem diagnosis for 100% (31 of 31) of stillbirths. For deaths <90 days, postmortem diagnoses included GBS sepsis (83.3%, 40 of 48), GBS meningitis (4.2%, 2 of 48), and GBS pneumonia (2.1%, 1 of 48).

Conclusions

Our study reveals significant heterogeneity in the contribution of invasive GBS disease to infant mortality across different countries, emphasizing the need for tailored prevention strategies. Moreover, our findings highlight the substantial impact of GBS on stillbirths, shedding light on a previously underestimated aspect in LMICs.

Group B Streptococcus CRISPR1 Typing of Maternal, Fetal, and Neonatal Infectious Disease Isolates Highlights the Importance of CC1 in In Utero Fetal Death

We performed a descriptive analysis of group B Streptococcus (GBS) isolates responsible for maternal and fetal infectious diseases from 2004 to 2020 at the University Hospital of Tours, France. This represents 115 isolates, including 35 isolates responsible for early-onset disease (EOD), 48 isolates responsible for late-onset disease (LOD), and 32 isolates from maternal infections. Among the 32 isolates associated with maternal infection, 9 were isolated in the context of chorioamnionitis associated with in utero fetal death. Analysis of neonatal infection distribution over time highlighted the decrease in EOD since the early 2000s, while LOD incidence has remained relatively stable. All GBS isolates were analyzed by sequencing their CRISPR1 locus, which is an efficient way to determine the phylogenetic affiliation of strains, as it correlates with the lineages defined by multilocus sequence typing (MLST). Thus, the CRISPR1 typing method allowed us to assign a clonal complex (CC) to all isolates; among these isolates, CC17 was predominant (60/115, 52%), and the other main CCs, such as CC1 (19/115, 17%), CC10 (9/115, 8%), CC19 (8/115, 7%), and CC23 (15/115, 13%), were also identified. As expected, CC17 isolates (39/48, 81.3%) represented the majority of LOD isolates. Unexpectedly, we found mainly CC1 isolates (6/9) and no CC17 isolates that were responsible for in utero fetal death. Such a result highlights the possibility of a particular role of this CC in in utero infection, and further investigations should be conducted on a larger group of GBS isolated in a context of in utero fetal death. IMPORTANCE Group B Streptococcus is the leading bacterium responsible for maternal and neonatal infections worldwide, also involved in preterm birth, stillbirth, and fetal death. In this study, we determined the clonal complex of all GBS isolates responsible for neonatal diseases (early- and late-onset diseases) and maternal invasive infections, including chorioamnionitis associated with in utero fetal death. All GBS was isolated at the University Hospital of Tours from 2004 to 2020. We described the local group B Streptococcus epidemiology, which confirmed national and international data concerning neonatal disease incidence and clonal complex distribution. Indeed, neonatal diseases are mainly characterized by CC17 isolates, especially in late-onset disease. Interestingly, we identified mainly CC1 isolates responsible for in utero fetal death. CC1 could have a particular role in this context, and such a result should be confirmed on a larger group of GBS isolated from in utero fetal death.

Cost-effectiveness analysis of maternal vaccination against Group B streptococcus in Japan

Background

Group B Streptococcus (GBS) is a leading pathogen causing life-threatening bacterial infections in neonates (early- or late-onset) and infants, and is associated with preterm and stillbirth. Japan introduced national guidelines to reduce early-onset neonatal GBS disease, with universal prenatal screening and intrapartum antimicrobial prophylaxis (IAP). However, screening/IAP does not prevent GBS associated late-onset disease, preterm or stillbirth. Maternal GBS vaccines in development are targeted at infant GBS disease but may provide benefit across perinatal outcomes. We aimed to assess cost-effectiveness of a future maternal GBS vaccine, for a base case prevention of infant GBS disease in combination with screening/IAP compared to screening/IAP alone.

Methods

We used a decision tree model to estimate cases of infant GBS disease, deaths, and neuro-developmental impairment (NDI), GBS-related stillbirths, and the associated costs and loss in Quality-Adjusted Life Years (QALYs). We calculate the threshold price at which a vaccine would be cost-effective assuming a cost-effectiveness threshold of ¥5 million/QALY. We explored the potential benefit of a maternal GBS vaccine that also prevents preterm birth in a scenario analysis.

Results

Maternal GBS vaccination in Japan could prevent an additional 142 infant GBS cases annually, including 5 deaths and 21 cases of NDI, and 13 stillbirths compared to screening/IAP alone. The incremental cost-effectiveness ratio (ICER) was ¥3.78 million/QALY with a vaccine cost of ¥5,000/dose. If the QALY lost for stillbirth is included, the ICER is reduced to ¥1.78 million/QALY. Median threshold vaccine price was ¥6,900 per dose (95 % uncertainty interval ¥5,100 to ¥9,200 per dose). If maternal GBS vaccination also prevented half of GBS-associated preterm, the ICER would be reduced to ¥1.88 million/QALY.

Conclusions

An effective maternal GBS vaccine is likely to be considered cost-effective in Japan at a price of ¥5,000/dose. Effectiveness against other adverse perinatal outcomes would increase health benefits and cost-effectiveness.

Changes in the Prevalence of Infection in Pregnant Women during the COVID-19 Lockdown

BACKGROUND

During the outbreak of SARS-CoV-2, strict mitigation measures and national lockdowns were implemented. Our objective was to investigate to what extent the prevalence of some infections in pregnancy was altered during different periods of the COVID-19 pandemic.

METHODS

This was a single centre retrospective cohort study conducted in the Netherlands on data collected from electronic patient files of pregnant women from January 2017 to February 2021. We identified three time periods with different strictness of mitigation measures: the first and second lockdown were relatively strict; the inter-lockdown period was less strict. The prevalence of the different infections (Group B Streptococcus (GBS)-carriage, urinary tract infections and Cytomegalovirus infection) during the lockdown was compared to the same time periods in previous years (2017-2019).

RESULTS

In the first lockdown, there was a significant decrease in GBS-carriage (19.5% in 2017-2019 vs. 9.1% in 2020; p = 0.02). In the period following the first lockdown and during the second, no differences in prevalence were found. There was a trend towards an increase in positive Cytomegalovirus IgM during the inter-lockdown period (4.9% in 2017-2019 vs. 12.8% in 2020; p = 0.09), but this did not reach statistical significance. The number of positive urine cultures did not significantly change during the study period.

CONCLUSIONS

During the first lockdown there was a reduction in GBS-carriage; further studies are warranted to look into the reason why.

Inferring longitudinal patterns of group B Streptococcus colonization during pregnancy

Maternal colonization by Group B Streptococcus (GBS) can lead to severe infection in neonates and has also been associated with prematurity and stillbirth. Better quantitative understanding of the trajectories of GBS carriage during pregnancy is essential for the design of informative epidemiological studies. Here, we describe analyses of published longitudinal data using Bayesian hidden Markov models, which involve the estimation of parameters related to the succession of latent states (infection status) and observations (culture positivity). In addition to quantifying infection acquisition and clearance probabilities, the statistical approach also suggests that for some longitudinal patterns of culture results, pregnant women were likely to have been GBS-colonized despite a negative diagnostic result. We believe this method, if used in future longitudinal studies of maternal GBS colonization, would improve our understanding of the pathologies linked to this bacterium and could also inform maternal GBS vaccine trial design.

Potential for Maternally Administered Vaccine for Infant Group B Streptococcus

BACKGROUND

Natural history studies have correlated serotype-specific anti-capsular polysaccharide (CPS) IgG in newborns with a reduced risk of group B streptococcal disease. A hexavalent CPS-cross-reactive material 197 glycoconjugate vaccine (GBS6) is being developed as a maternal vaccine to prevent invasive group B streptococcus in young infants.

METHODS

In an ongoing phase 2, placebo-controlled trial involving pregnant women, we assessed the safety and immunogenicity of a single dose of various GBS6 formulations and analyzed maternally transferred anti-CPS antibodies. In a parallel seroepidemiologic study that was conducted in the same population, we assessed serotype-specific anti-CPS IgG concentrations that were associated with a reduced risk of invasive disease among newborns through 89 days of age to define putative protective thresholds.

RESULTS

Naturally acquired anti-CPS IgG concentrations were associated with a reduced risk of disease among infants in the seroepidemiologic study. IgG thresholds that were determined to be associated with 75 to 95% reductions in the risk of disease were 0.184 to 0.827 μg per milliliter. No GBS6-associated safety signals were observed among the mothers or infants. The incidence of adverse events and of serious adverse events were similar across the trial groups for both mothers and infants; more local reactions were observed in the groups that received GBS6 containing aluminum phosphate. Among the infants, the most common serious adverse events were minor congenital anomalies (umbilical hernia and congenital dermal melanocytosis). GBS6 induced maternal antibody responses to all serotypes, with maternal-to-infant antibody ratios of approximately 0.4 to 1.3, depending on the dose. The percentage of infants with anti-CPS IgG concentrations above 0.184 μg per milliliter varied according to serotype and formulation, with 57 to 97% of the infants having a seroresponse to the most immunogenic formulation.

CONCLUSIONS

GBS6 elicited anti-CPS antibodies against group B streptococcus in pregnant women that were transferred to infants at levels associated with a reduced risk of invasive group B streptococcal disease. (Funded by Pfizer and the Bill and Melinda Gates Foundation; C1091002 ClinicalTrials.gov number, NCT03765073.).

Prevalence, Antimicrobial Susceptibility Pattern and Associated Factors of Group B Streptococcus Among Pregnant Women Attending Antenatal Care at Bule Hora University Teaching Hospital, Southern Ethiopia

Background

In many parts of the world, Group B Streptococcus (GBS) is a major cause of maternal and neonatal illness and mortality. It has a negative impact on neonatal and pregnancy outcomes. A worrisome problem in Ethiopia is the unknown rate of antibiotic resistance and the risk factors connected to GBS infections.

Objective

This study was to determine the prevalence, antibiotic susceptibility pattern, and related variables of Group B Streptococcus among pregnant women receiving prenatal treatment conducted at Bule Hora University Teaching Hospital, Southern Ethiopia, between June 1 and August 30, 2022.

Methods

An institutional-based cross-sectional study was conducted among 213 pregnant women attending antenatal care at Bule Hora University Teaching Hospital. Data on sociodemographic and related factors were gathered using structured questionnaires. The study's participants were selected using the consecutive sampling method. The lower vaginal/rectum area was brushed with a sterile cotton swab to capture the vaginal/rectum swab sample, which was then examined using microbiological techniques. The Kirby-Bauer disc diffusion method was used to assess antibiotic susceptibility in GBS isolates. Logistic regression analysis was performed on the data using SPSS version 26. It was deemed statistically significant when the p-value was 0.05 with a 95% confidence interval (CI).

Results

The overall prevalence of GBS was 16.9% (CI: 0.12-0.23). A history of prematurity of the membrane (AOR: 3.35, 95% CI: 1.19-9.45), a history of stillbirth (AOR: 2.88, 95% CI: 1.07-7.71), and preterm delivery history (AOR: 3.41, 95% CI: 1.31-8.89) (p 0.05) were independent predictors of GBS infection. Cefepime had the highest resistance at 58.3%. Most GBS isolates showed high susceptibility to vancomycin (97.2%) and ampicillin (91.7%). Multidrug resistance was 13.9%.

Conclusion

The prevalence of GBS was considerably high among pregnant women in this study. This finding emphasises the need for routine screening and testing of antimicrobial susceptibility to provide antibiotic prophylaxis and minimise newborn infection and comorbidity.

Early-onset group B streptococcal disease in African countries and maternal vaccination strategies

Invasive group B streptococcal (GBS) disease is the commonest perinatally-acquired bacterial infection in newborns; the burden is higher in African countries where intrapartum antibiotic prophylaxis strategies are not feasible. In sub-Saharan Africa, almost one in four newborns with GBS early-onset disease will demise, and one in ten survivors have moderate or severe neurodevelopmental impairment. A maternal GBS vaccine to prevent invasive GBS disease in infancy is a pragmatic and cost-effective preventative strategy for Africa. Hexavalent polysaccharide protein conjugate and Alpha family surface protein vaccines are undergoing phase II clinical trials. Vaccine licensure may be facilitated by demonstrating safety and immunological correlates/thresholds suggestive of protection against invasive GBS disease. This will then be followed by phase IV effectiveness studies to assess the burden of GBS vaccine preventable disease, including the effect on all-cause neonatal infections, neonatal deaths and stillbirths.

Group B Streptococcus infection-induced ovarian vein thrombosis identified during cesarean section: A case report and a literature review

RATIONALE

Ovarian vein thrombosis (OVT) is a rare yet potentially life-threatening condition associated with thromboembolic events. Group B Streptococcus (GBS) is a type of β-hemolytic Gram-positive bacterium known for asymptomatic colonization in the lower genital and gastrointestinal tracts. Here we reported a 35-year-old multiparous woman with gestational diabetes who suffered from placental abruption, stillbirth, OVT, septic shock, and renal failure due to severe GBS infection.

PATIENT CONCERNS

A 35-year-old woman with gestational diabetes presented with acute and sustained lower abdominal cramping, vaginal bleeding, and fever at 35 gestational weeks.

DIAGNOSES

Based on preoperative ultrasound and intraoperative findings, the patient was diagnosed with placental abruption, intrauterine fetal demise, and right OVT. GBS was cultured from the amniotic fluid obtained during cesarean section.

INTERVENTIONS

The patient underwent a right adnexectomy during a cesarean section and received intravenous antibiotics. Subsequently, an ultrasound-guided uterine curettage was performed due to recurrent fever.

OUTCOMES

After a prolonged course of intravenous antibiotics for over a month, the patient recovered and was discharged from the hospital.

LESSONS

This case underscores the need for early initiation of anticoagulant protocols in cases of OVT, particularly when GBS infection is identified as a predisposing factor. Further research and awareness are warranted to better understand the relationship between GBS infection and OVT and to optimize management strategies in such cases.

COVID-19 Vaccine Hesitancy among English-Speaking Pregnant Women Living in Rural Western United States

This mixed-method study investigated vaccine hesitancy among pregnant women living in rural western United States and their response to social media ads promoting COVID-19 vaccine uptake. Thirty pregnant or recently pregnant participants who live in rural zip codes in Washington, Oregon, California, and Idaho were interviewed between November 2022 and March 2023. Interviews were transcribed and coded, while the ad ratings were analyzed using linear mixed models. The study identified five main themes related to vaccine uptake, including perceived risk of COVID, sources of health information, vaccine hesitancy, and relationships with care providers. Participants rated ads most highly that used peer-based messengers and negative outcome-based content. Ads with faith-based and elder messengers were rated significantly lower than peer messengers (p = 0.04 and 0.001, respectively). An activation message was also rated significantly less favorably than negative outcome-based content (p = 0.001). Participants preferred evidence-based information and the ability to conduct their own research on vaccine safety and efficacy rather than being told to get vaccinated. Primary concerns of vaccine-hesitant respondents included the short amount of time the vaccine had been available and perceived lack of research on its safety during pregnancy. Our findings suggests that tailored messaging using peer-based messengers and negative outcome-based content can positively impact vaccine uptake among pregnant women living in rural areas of the Western United States.

Group B Streptococcus and the risk of perinatal morbidity and mortality following term labor

Streptococcus agalactiae (group B Streptococcus) colonizes the genital tract of approximately 20% of pregnant women. In the absence of intervention, approximately 1% of infants born to colonized mothers exhibit a clinical infection. This has led to implementation of screening and intervention in the form of intrapartum antibiotic prophylaxis in many countries, including the United States. However, screening has not been introduced in a substantial minority of other countries because of the absence of supportive level 1 evidence, the very large number needed to treat to prevent 1 case, and concerns about antimicrobial resistance. Optimal screening would involve rapid turnaround (to facilitate intrapartum testing) and report antibiotic sensitivity, but no such method exists. There is significant scope for a personalized medicine approach, targeting intrapartum antibiotic prophylaxis to cases at greatest risk, but the pathogen and host factors determining the risk of invasive disease are incompletely understood. Epidemiologic data have indicated the potential of prelabor invasion of the uterus by group B Streptococcus, and metagenomic analysis revealed the presence of group B Streptococcus in the placenta in approximately 5% of pregnant women at term before onset of labor and membrane rupture. However, the determinants and consequences of prelabor invasion of the uterus by group B Streptococcus remain to be established. The vast majority (98%) of invasive neonatal disease is caused by 6 serotypes, and hexavalent vaccines against these serotypes have completed phase 2 trials. However, an obstacle to phase 3 studies is conducting an adequately powered trial to demonstrate clinical effectiveness given that early-onset disease affects approximately 1 in 1000 births in the absence of vaccination.

Long-term Risk of Epilepsy Following Invasive Group B Streptococcus Disease in Neonates in Denmark

Importance

The risk of epilepsy after neonatal invasive Group B Streptococcus (iGBS) disease, particularly iGBS sepsis, is poorly understood.

Objective

To examine the association between neonatal iGBS (sepsis or meningitis) and long-term risk of epilepsy, stratified by sex, prematurity, and maternal socioeconomic position (SEP).

Design, Setting, and Participants

This population-based cohort study was conducted in Denmark with an inclusion period from 1997 through 2017 and follow-up until the end of 2018. A general population comparison cohort was randomly sampled and matched up to 10:1 to the exposed cohort. Linkage between Danish national registers were applied for data collection. Participants were infants aged 0 to 89 days. The general population comparison cohort was matched by sex, the child's year and month of birth, and gestational age. SEP was defined by maternal income and education.

Exposure

Hospital-diagnosed iGBS (sepsis or meningitis) during the first 89 days after birth.

Outcomes and measures

Epilepsy was defined by International Statistical Classification of Diseases and Related Health Problems, Tenth Revision codes and/or prescription codes for antiepileptic drugs using Danish medical registry data. Cumulative risk (CR) of epilepsy was calculated by treating death as a competing event. Cox proportional hazards regression was used to estimate hazard ratios with 95% CIs. Effect modification by sex, prematurity, and maternal SEP was assessed on an additive scale.

Results

A total of 1432 children (792 [55.3%] boys; 1126 [78.6%] with gestational age ≥37 weeks) were identified with iGBS disease: 1264 with sepsis and 168 with meningitis. In the comparison cohort, there were 14 211 children (7869 [55.4%] boys; 11 260 [79.2%] with gestational age ≥37 weeks). The overall (0 to 22 years) CR of epilepsy was 3.6% (95% CI, 2.6%-5.0%) in children with iGBS disease and 2.3% (95% CI, 1.9%-2.7%) in the comparison cohort. The overall CR of epilepsy for iGBS meningitis was 15.1% (95% CI, 8.9%-22.8%) and 2.2% (95% CI, 1.4%-3.4%) for iGBS sepsis. The adjusted hazard ratio for epilepsy in children with iGBS disease was 2.04 (95% CI, 1.46-2.85). Being a boy, born premature, or born to a mother belonging to a low SEP group was associated with an increased risk of epilepsy in later childhood.

Conclusion

In this population-based cohort study of 1432 neonates, iGBS disease was associated with a higher incidence of epilepsy in later childhood, notably after meningitis. Premature birth, sex, and low maternal SEP modified the association.

20 million pregnant women with group B streptococcus carriage: consequences, challenges, and opportunities for prevention

PURPOSE OF REVIEW

Intrapartum antibiotic prophylaxis (IAP) is currently the only recommended preventive approach against clinical consequences of maternal Group B Streptococcus (GBS) colonization. In this review, we discuss new findings of total perinatal GBS burden and relative effectiveness of differing targeting of IAP, notably microbiology-based and risk factor-based screening, including potential limitations. Finally, we provide updates on maternal GBS vaccines and their potential cost-effectiveness in disease reduction.

RECENT FINDINGS

Updated estimates of the burden of GBS related to pregnancy outcomes show (1) early-onset GBS disease incidence and deaths are high in some low- and middle-income countries where IAP has not been implemented and (2) late-onset GBS disease, preterm birth, and stillbirth, which are not preventable by IAP, remain a public health problem in both high and low-middle income settings. Observational evidence indicates that microbiology-based screening may be more effective than risk factor-based screening, but even in high-income countries, compliance is imperfect. To address the need for alternative prevention strategies, several maternal vaccine candidates are in clinical development, and modelling suggests these could be cost-effective in most scenarios.

SUMMARY

Recent progress in GBS vaccine research holds promise of reducing the large and preventable burden of mortality and disability caused by GBS disease, especially in higher-burden settings where clinical and laboratory services may be limited. Importantly vaccines also hold potential to prevent GBS stillbirths and GBS-associated preterm births.

Safety and immunogenicity of the group B streptococcus vaccine AlpN in a placebo-controlled double-blind phase 1 trial

Group B streptococcus (GBS) is a leading cause of life-threatening neonatal infections and subsets of adverse pregnancy outcomes. Essentially all GBS strains possess one allele of the alpha-like protein (Alp) family. A maternal GBS vaccine, consisting of the fused N-terminal domains of the Alps αC and Rib (GBS-NN), was recently demonstrated to be safe and immunogenic in healthy adult women. To enhance antibody responses to all clinically relevant Alps, a second-generation vaccine has been developed (AlpN), also containing the N-terminal domain of Alp1 and the one shared by Alp2 and Alp3. In this study, the safety and immunogenicity of AlpN is assessed in a randomized, double-blind, placebo-controlled, and parallel-group phase I study, involving 60 healthy non-pregnant women. AlpN is well tolerated and elicits similarly robust and persistent antibody responses against all four Alp-N-terminal domains, resulting in enhanced opsonophagocytic killing of all Alp serotypes covered by the vaccine.

The Blood Microbiome and Health: Current Evidence, Controversies, and Challenges

Blood is conventionally thought to be sterile. However, emerging evidence on the blood microbiome has started to challenge this notion. Recent reports have revealed the presence of genetic materials of microbes or pathogens in the blood circulation, leading to the conceptualization of a blood microbiome that is vital for physical wellbeing. Dysbiosis of the blood microbial profile has been implicated in a wide range of health conditions. Our review aims to consolidate recent findings about the blood microbiome in human health and to highlight the existing controversies, prospects, and challenges around this topic. Current evidence does not seem to support the presence of a core healthy blood microbiome. Common microbial taxa have been identified in some diseases, for instance, Legionella and Devosia in kidney impairment, Bacteroides in cirrhosis, Escherichia/Shigella and Staphylococcus in inflammatory diseases, and Janthinobacterium in mood disorders. While the presence of culturable blood microbes remains debatable, their genetic materials in the blood could potentially be exploited to improve precision medicine for cancers, pregnancy-related complications, and asthma by augmenting patient stratification. Key controversies in blood microbiome research are the susceptibility of low-biomass samples to exogenous contamination and undetermined microbial viability from NGS-based microbial profiling, however, ongoing initiatives are attempting to mitigate these issues. We also envisage future blood microbiome research to adopt more robust and standardized approaches, to delve into the origins of these multibiome genetic materials and to focus on host–microbe interactions through the elaboration of causative and mechanistic relationships with the aid of more accurate and powerful analytical tools.

Association of infant Rib and Alp1 surface protein N-terminal domain immunoglobulin G and invasive Group B Streptococcal disease in young infants

BACKGROUND

Vaccine development for Group B Streptococcus (GBS), a common cause of invasive disease in early-infancy and adverse pregnancy outcomes, include exploring widely-expressed GBS surface proteins as vaccine epitopes. We investigated the association between natural infant serum IgG against the RibN and Alp1N domains and risk of invasive GBS disease caused by isolates expressing these proteins.

METHODS

We analyzed maternal and infant serum samples from GBS disease cases and infants born to GBS-colonized women controls. Bayesian modelling was used to calculate the GBS homotypic IgG concentration associated with risk reduction of invasive disease in the infant.

RESULTS

PCR-based typing of 85 GBS invasive isolates showed 46 and 24 possessing the gene for Rib and Alp1, respectively. These were matched to 46 and 36 infant controls whose mothers were colonized with GBS expressing Rib and Alp1, respectively. RibN IgG geometric mean concentrations (GMC) were lower in cases than controls among infants (0.01; 95 %CI: 0.01-0.02 vs 0.04; 95 %CI: 0.03-0.06; p < 0.001), no significant difference was found between maternal RibN IgG GMC in cases compared to controls. Alp1N IgG GMC was also lower in infant cases (0.02; 95 %CI: 0.01-0.03) than controls (0.05; 95 %CI: 0.04-0.07; p < 0.001); albeit not so in mothers. An infant IgG threshold ≥ 0.428 and ≥ 0.112 µg/mL was associated with 90 % risk reduction of invasive GBS disease due to Rib and Alp1 expressing strains, respectively.

DISCUSSION

Lower serum RibN and Alp1N IgG GMC were evident in infants with invasive GBS disease compared with controls born to women colonized with GBS expressing the homotypic protein. These data support the evaluation of Alp family proteins as potential vaccine candidates against invasive GBS disease.

Alterations of the vaginal microbiome in healthy pregnant women positive for group B Streptococcus colonization during the third trimester

BACKGROUND

Streptococcus agalactiae or group B Streptococcus (GBS) asymptomatically colonizes the genitourinary tracts of up to 30% of pregnant women. Globally, GBS is an important cause of neonatal morbidity and mortality. GBS has recently been linked to adverse pregnancy outcomes. The potential interactions between GBS and the vaginal microbiome composition remain poorly understood. In addition, little is known about the vaginal microbiota of pregnant Egyptian women.

RESULTS

Using V3-V4 16S rRNA next-generation sequencing, we examined the vaginal microbiome in GBS culture-positive pregnant women (22) and GBS culture-negative pregnant women (22) during the third trimester in Ismailia, Egypt. According to the alpha-diversity indices, the vaginal microbiome of pregnant GBS culture-positive women was significantly more diverse and less homogenous. The composition of the vaginal microbiome differed significantly based on beta-diversity between GBS culture-positive and culture-negative women. The phylum Firmicutes and the family Lactobacillaceae were significantly more abundant in GBS-negative colonizers. In contrast, the phyla Actinobacteria, Tenericutes, and Proteobacteria and the families Bifidobacteriaceae, Mycoplasmataceae, Streptococcaceae, Corynebacteriaceae, Staphylococcaceae, and Peptostreptococcaceae were significantly more abundant in GBS culture-positive colonizers. On the genus and species levels, Lactobacillus was the only genus detected with significantly higher relative abundance in GBS culture-negative status (88%), and L. iners was the significantly most abundant species. Conversely, GBS-positive carriers exhibited a significant decrease in Lactobacillus abundance (56%). In GBS-positive colonizers, the relative abundance of the genera Ureaplasma, Gardnerella, Streptococcus, Corynebacterium, Staphylococcus, and Peptostreptococcus and the species Peptostreptococcus anaerobius was significantly higher. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways related to the metabolism of cofactors and vitamins, phosphatidylinositol signaling system, peroxisome, host immune system pathways, and host endocrine system were exclusively enriched among GBS culture-positive microbial communities. However, lipid metabolism KEGG pathways, nucleotide metabolism, xenobiotics biodegradation and metabolism, genetic information processing pathways associated with translation, replication, and repair, and human diseases (Staphylococcus aureus infection) were exclusively enriched in GBS culture-negative communities.

CONCLUSIONS

Understanding how perturbations of the vaginal microbiome contribute to pregnancy complications may result in the development of alternative, targeted prevention strategies to prevent maternal GBS colonization. We hypothesized associations between inferred microbial function and GBS status that would need to be confirmed in larger cohorts.

A Novel Conserved Protein in Streptococcus agalactiae, BvaP, Is Important for Vaginal Colonization and Biofilm Formation

Streptococcus agalactiae (group B streptococcus [GBS]) infections in neonates are often fatal and strongly associated with maternal GBS vaginal colonization. Here, we investigated the role of an uncharacterized protein, BvaP, in GBS vaginal colonization. bvaP was previously identified as the most highly upregulated gene in the GBS A909 transcriptome when comparing vaginal colonization to growth in liquid culture. We found that the absence of BvaP affects the ability of GBS to adhere to extracellular matrix components and human vaginal epithelial cells, and the ability of a ΔbvaP mutant to colonize the murine vaginal tract was significantly decreased. Cellular morphological alterations such as changes in cell shape, chain length, and clumping were also observed in a knockout mutant strain. Given its high expression level in vivo, high degree of conservation among GBS strains, and role in vaginal colonization, BvaP may be an eligible target for GBS vaccination and/or drug therapy. IMPORTANCE Neonatal GBS disease is a major cause of morbidity and mortality, and maternal vaginal colonization is the leading risk factor for the disease. Colonization prevention would greatly impact the rates of disease transmission, but vaccine development has stalled as capsular polysaccharide vaccines have low immunogenicity in vivo. While these vaccines are still in development, the addition of a protein conjugate may prove fruitful in increasing immunogenicity and strain coverage across GBS serotypes. Previous research identified sak_1753 as a highly upregulated gene during murine vaginal colonization. This study reveals that Sak_1753 is required to maintain proper GBS cellular morphology and colonization phenotypes and is required for full in vivo vaginal colonization in a murine model. We have renamed Sak_1753 group B streptococcus vaginal adherence protein (BvaP). The findings of this study indicate that BvaP is important for GBS colonization of the vaginal tract and, given its high expression level in vivo and strain conservation, may be a candidate for vaccine development.

Group B Streptococcus and Pregnancy: Critical Concepts and Management Nuances

Importance

Group B Streptococcus (GBS) is a common pathogen with an effective treatment. However, it remains a significant cause of neonatal sepsis, morbidity, and mortality. The screening and management of this infection are some of the first concepts learned during medical training in obstetrics. However, effective screening and evidence-based management of GBS are nuanced with many critical caveats.

Objective

The objectives of this review are to discuss the essential aspects of GBS screening and management and to highlight recent changes to recommendations and guidelines.

Evidence Acquisition

Original research articles, review articles, and guidelines on GBS were reviewed.

Results

The following recommendations are based on review of the evidence and professional society guidelines. Screening for GBS should occur between 36 weeks and the end of the 37th week. The culture swab should go 2 cm into the vagina and 1 cm into the anus. Patients can perform their own swabs as well. Penicillin allergy testing has been shown to be safe in pregnancy. Patients with GBS in the urine should be treated at term with antibiotic prophylaxis, independent of the colony count of the culture. Patients who are GBS-positive with preterm and prelabor rupture of membranes after 34 weeks are not candidates for expectant management, as this population has higher rates of neonatal infectious complications. Patients with a history of GBS colonization in prior pregnancy who are GBS-unknown in this current pregnancy and present with labor should receive intrapartum prophylaxis. Work on the GBS vaccine continues.

Conclusions

Although all of the efforts and focus on neonatal early-onset GBS infection have led to lower rates of disease, GBS still remains a major cause of neonatal morbidity and mortality requiring continued vigilance from obstetric providers.

The Group B Streptococcal Adhesin BspC Interacts with Host Cytokeratin 19 To Promote Colonization of the Female Reproductive Tract

Streptococcus agalactiae, otherwise known as Group B Streptococcus (GBS), is an opportunistic pathogen that vaginally colonizes approximately one third of healthy women. During pregnancy, this can lead to in utero infection, resulting in premature rupture of membranes, chorioamnionitis, and stillbirths. Furthermore, GBS causes serious infection in newborns, including sepsis, pneumonia, and meningitis. Previous studies have indicated that GBS antigen (Ag) I/II family proteins promote interaction with vaginal epithelial cells; thus, we hypothesized that the Ag I/II Group B streptococcal surface protein C (BspC) contributes to GBS colonization of the female reproductive tract (FRT). Here, we show that a ΔbspC mutant has decreased bacterial adherence to vaginal, ecto-, and endocervical cells, as well as decreased auto-aggregation and biofilm-like formation on cell monolayers. Using a murine model of vaginal colonization, we observed that the ΔbspC mutant strain exhibited a significant fitness defect compared to wild-type (WT) GBS and was less able to ascend to the cervix and uterus in vivo, resulting in reduced neutrophil chemokine signaling. Furthermore, we determined that BspC interacts directly with the host intermediate filament protein cytokeratin 19 (K19). Surface localization of K19 was increased during GBS infection, and interaction was mediated by the BspC variable (V) domain. Finally, mice treated with a drug that targets the BspC V-domain exhibited reduced bacterial loads in the vaginal lumen and reproductive tissues. These results demonstrate the importance of BspC in promoting GBS colonization of the FRT and that it may be targeted therapeutically to reduce GBS vaginal persistence and ascending infection. IMPORTANCE Group B Streptococcus (GBS) asymptomatically colonizes the female reproductive tract (FRT) of up to one third of women, but GBS carriage can lead to adverse pregnancy outcomes, including premature rupture of membranes, preterm labor, and chorioamnionitis. GBS colonization during pregnancy is also the largest predisposing factor for neonatal GBS disease, including pneumonia, sepsis, and meningitis. The molecular interactions between bacterial surface proteins and the host cell receptors that promote GBS colonization are vastly understudied, and a better understanding would facilitate development of novel therapeutics to prevent GBS colonization and disease. Here, we characterize the role of the GBS surface protein BspC in colonization of the FRT. We show for the first time that GBS infection induces cytokeratin 19 (K19) surface localization on vaginal epithelial cells; GBS then uses the BspC V-domain to interact with K19 to promote colonization and ascending infection. Furthermore, this interaction can be targeted therapeutically to reduce GBS carriage.

An Initial Survey on the Prevalence of Group B Streptococcus (GBS) among Yemeni Pregnant Women in Sana’a City

Background

Infection with group B Streptococcus (GBS) is still a neonatal life-threatening illness, especially in developing countries such as Yemen.

Objective

This study was aimed at determining the vaginal colonization rate and antibiotic susceptibility pattern of GBS among Yemeni pregnant women.

Methods

We conducted a cross-sectional study over a four-month period involving 210 pregnant women at the 35th to 39th gestational weeks who visited Gaza medical center in Sana'a city, Yemen. The collected vaginal swab specimen was inoculated in the Todd-Hewitt enrichment broth and incubated for 24 h and then subcultured on a 5% human blood agar plate. All positive cultures identified as GBS were subjected to antibiotic susceptibility tests using the disk diffusion method.

Results

Out of 210 recruited pregnant women, 23 (10.95%) were GBS vaginal carriers. All GBS isolates were sensitive to penicillin, ampicillin, levofloxacin, cefotaxime, and vancomycin.

Conclusion

Based on the study's results, approximately eleven out of every 100 pregnant women in Sana'a city are vaginally colonized by GBS. Beta-lactam antibiotics remain the drug of choice to treat and prevent GBS infections. A prenatal screening policy is urgently needed for Yemeni pregnant women.

Sublingual immunisation with GBS serotype III capsular polysaccharide-tetanus toxoid conjugate vaccine induces systemic and mucosal antibody responses which are opsonophagocytic and inhibit GBS colonisation of vaginal epithelial cells

No vaccines are currently licensed against Group B streptococcus (GBS), an important cause of morbidity and mortality in babies and adults. Using a mouse model, and in vitro opsonophagocytosis and colonisation assays, we evaluated the potential of a sublingually-administered polysaccharide-conjugate vaccine against GBS serotype III. Sublingual immunisation of mice with 10 µg of GBS conjugate vaccine once a week for 5 weeks induced a substantial systemic IgG anti-polysaccharide response which was similar to the level induced by subcutaneous immunsation. In addition, sublingual immunisation also induced mucosal (IgA) antibody responses in the mouth, intestines and vagina. Immune sera and intestinal washes were functionally active at mediating killing of the homologous GBS serotype III in an opsonophagocytosis assay. In addition, intestinal and vaginal washes inhibited the colonisation of mouse vaginal epithelial cells by the vaccine homologous strain. These results suggest that, in addition to the induction of high levels of IgG antibodies that could be transduced from the immunised mother to the foetus to protect the newborn against GBS infection, sublingual immunisation can elicit a substantial mucosal antibody response which might play an important role in the prevention of GBS colonisation in immunised women, thereby eliminating the risk of GBS transmission from the mother to the baby during pregnancy or at birth.

Streptococcus agalactiae cadD alleviates metal stress and promotes intracellular survival in macrophages and ascending infection during pregnancy

Perinatal infection with Streptococcus agalactiae, or Group B Streptococcus (GBS), is associated with preterm birth, neonatal sepsis, and stillbirth. Here, we study the interactions of GBS with macrophages, essential sentinel immune cells that defend the gravid reproductive tract. Transcriptional analyses of GBS-macrophage co-cultures reveal enhanced expression of a gene encoding a putative metal resistance determinant, cadD. Deletion of cadD reduces GBS survival in macrophages, metal efflux, and resistance to metal toxicity. In a mouse model of ascending infection during pregnancy, the ΔcadD strain displays attenuated bacterial burden, inflammation, and cytokine production in gestational tissues. Furthermore, depletion of host macrophages alters cytokine expression and decreases GBS invasion in a cadD-dependent fashion. Our results indicate that GBS cadD plays an important role in metal detoxification, which promotes immune evasion and bacterial proliferation in the pregnant host.

Clinical Profile and Risk Factors of Group B Streptococcal Colonization in Mothers from the Eastern District of China

Objective

The main aim of this study was to determine the prevalence, capsular genotyping, antimicrobial susceptibility, and associated factors of colonizing Group B Streptococcus (GBS) in pregnant women admitted to a hospital in Jinan, East China.

Methods

Demographic data, clinical characteristics, and vaginal and rectal swabs were obtained from a group of expecting mothers subjected to GBS screening at the late stage of pregnancy who went into labor over the period from November 2019 to October 2020. Identification of GBS and determination of antimicrobial resistance patterns were performed using a BD Phoenix-100 system. Capsular genotypes were analyzed using polymerase chain reaction and the associated factors were evaluated via logistic regression.

Result

A total of 2761 pregnant women were recruited for this study. The GBS colonization rate was 6.70% (185/2761). Among the 172 GBS strains examined, all were susceptible to vancomycin and linezolid. Resistance was the highest for erythromycin (80.2%), followed by clindamycin (75.0%), levofloxacin (65.1%), and tetracycline (57.6%). The most common serotype identified was Ia (61.0%), followed by III (29.7%), VI (4.6%), II (3.5%), VII (0.6%), and a nontypeable strain. Risk factors for maternal GBS colonization included maternal age (older than 30 years) (OR = 1.913 (1.662, 2.478)), gestational age at birth (average gestational age) (OR = 1.992 (1.445, 2.746)), and prelabor rupture of membrane (OR = 3.838 (1.619, 9.099)).

Conclusion

The prevalence of GBS was relatively low. The maternal age was a factor associated with GBS colonization. Subjects showing GBS positivity during late pregnancy were prone to prolonged rupture of the membrane (PROM) and birth at lower a gestation age than the GBS-negative group. Penicillin could still be used as the first agent of choice for intrapartum antibiotic prophylaxis (IAP).

Investigation and management of stillbirth: a descriptive review of major guidelines

Stillbirth is a common and devastating pregnancy complication. The aim of this study was to review and compare the recommendations of the most recently published guidelines on the investigation and management of this adverse outcome. A descriptive review of guidelines from the American College of Obstetricians and Gynecologists (ACOG), the Royal College of Obstetricians and Gynecologists (RCOG), the Perinatal Society of Australia and New Zealand (PSANZ), the Society of Obstetricians and Gynecologists of Canada (SOGC) on stillbirth was carried out. Regarding investigation, there is consensus that medical history and postmortem examination are crucial and that determining the etiology may improve care in a subsequent pregnancy. All guidelines recommend histopathological examination of the placenta, genetic analysis and microbiology of fetal and placental tissues, offering less invasive techniques when autopsy is declined and a Kleihauer test to detect large feto-maternal hemorrhage, whereas they discourage routine screening for inherited thrombophilias. RCOG and SOGC also recommend a complete blood count, coagulopathies' testing, anti-Ro and anti-La antibodies' measurement in cases of hydrops and parental karyotyping. Discrepancies exist among the reviewed guidelines on the definition of stillbirth and the usefulness of thyroid function tests and maternal viral screening. Moreover, only ACOG and RCOG discuss the management of stillbirth. They agree that, in the absence of coagulopathies, expectant management should be considered and encourage vaginal birth, but they suggest different labor induction protocols and different management in subsequent pregnancies. It is important to develop consistent international practice protocols, in order to allow effective determination of the underlying causes and optimal management of stillbirths, while identifying the gaps in the current literature may highlight the need for future research.

Genomic Analyses Identify Manganese Homeostasis as a Driver of Group B Streptococcal Vaginal Colonization

Group B Streptococcus (GBS) is associated with severe infections in utero and in newborn populations, including pneumonia, sepsis, and meningitis. GBS vaginal colonization of the pregnant mother is an important prerequisite for transmission to the newborn and the development of neonatal invasive disease; however, our understanding of the factors required for GBS persistence and ascension in the female reproductive tract (FRT) remains limited. Here, we utilized a GBS mariner transposon (Krmit) mutant library previously developed by our group and identified underrepresented mutations in 535 genes that contribute to survival within the vaginal lumen and colonization of vaginal, cervical, and uterine tissues. From these mutants, we identified 47 genes that were underrepresented in all samples collected, including mtsA, a component of the mtsABC locus, encoding a putative manganese (Mn²⁺)-dependent ATP-binding cassette transporter. RNA sequencing analysis of GBS recovered from the vaginal tract also revealed a robust increase of mtsA expression during vaginal colonization. We engineered an ΔmtsA mutant strain and found by using inductively coupled plasma mass spectrometry that it exhibited decreased concentrations of intracellular Mn²⁺, confirming its involvement in Mn²⁺ acquisition. The ΔmtsA mutant was significantly more susceptible to the metal chelator calprotectin and to oxidative stressors, including both H₂O₂ and paraquat, than wild-type (WT) GBS. We further observed that the ΔmtsA mutant strain exhibited a significant fitness defect in comparison to WT GBS in vivo by using a murine model of vaginal colonization. Taken together, these data suggest that Mn²⁺ homeostasis is an important process contributing to GBS survival in the FRT.

Detecting Genetic Variation of Colonizing Streptococcus agalactiae Genomes in Humans: A Precision Protocol

Deciphering the genotypic diversity of within-individual pathogens and verifying the evolutionary model can help elucidate resistant genotypes, virulent subpopulations, and the mechanism of opportunistic pathogenicity. However, observed polymorphic mutations (PMs) are rare and difficult to be detected in the “dominant-lineage” model of bacterial infection due to the low frequency. The four pooled group B Streptococcus (GBS) samples were collected from the genital tracts of healthy pregnant women, and the pooled samples and the isogenic controls were genomically sequenced. Using the PMcalling program, we detected the PMs in samples and compared the results between two technical duplicates, GBS-M001T and GBS-M001C. Tested with simulated datasets, the PMcalling program showed high sensitivity especially in low-frequency PMs and reasonable specificity. The genomic sequence data from pooled samples of GBS colonizing carrier pregnant women were analyzed, and few high-frequency PMs and some low-frequency PMs were discovered, indicating a dominant-lineage evolution model. The PMs mainly were nonsynonymous and enriched in quorum sensing, glycolysis/gluconeogenesis, ATP-binding cassette (ABC) transporters, etc., suggesting antimicrobial or environmental selective pressure. The re-analysis of the published Burkholderia dolosa data showed a diverse-community model, and only a few low-frequency PMs were shared between different individuals. Genes of general control non-repressible 5-related N-acetyltransferases family, major facilitator superfamily (MFS) transporter, and ABC transporter were positive selection candidates. Our findings indicate an unreported nature of the dominant-lineage model of GBS colonization in healthy women, and a formerly not observed mutation pool in a colonized microbial community, possibly maintained by selection pressure.

Group B streptococcus infection during pregnancy and infancy: estimates of regional and global burden

BACKGROUND

Group B streptococcus (GBS) colonisation during pregnancy can lead to invasive GBS disease (iGBS) in infants, including meningitis or sepsis, with a high mortality risk. Other outcomes include stillbirths, maternal infections, and prematurity. There are data gaps, notably regarding neurodevelopmental impairment (NDI), especially after iGBS sepsis, which have limited previous global estimates. In this study, we aimed to address this gap using newly available multicountry datasets.

METHODS

We collated and meta-analysed summary data, primarily identified in a series of systematic reviews published in 2017 but also from recent studies on NDI and stillbirths, using Bayesian hierarchical models, and estimated the burden for 183 countries in 2020 regarding: maternal GBS colonisation, iGBS cases and deaths in infants younger than 3 months, children surviving iGBS affected by NDI, and maternal iGBS cases. We analysed the proportion of stillbirths with GBS and applied this to the UN-estimated stillbirth risk per country. Excess preterm births associated with maternal GBS colonisation were calculated using meta-analysis and national preterm birth rates.

FINDINGS

Data from the seven systematic reviews, published in 2017, that informed the previous burden estimation (a total of 515 data points) were combined with new data (17 data points) from large multicountry studies on neurodevelopmental impairment (two studies) and stillbirths (one study). A posterior median of 19·7 million (95% posterior interval 17·9-21·9) pregnant women were estimated to have rectovaginal colonisation with GBS in 2020. 231 800 (114 100-455 000) early-onset and 162 200 (70 200-394 400) late-onset infant iGBS cases were estimated to have occurred. In an analysis assuming a higher case fatality rate in the absence of a skilled birth attendant, 91 900 (44 800-187 800) iGBS infant deaths were estimated; in an analysis without this assumption, 58 300 (26 500-125 800) infant deaths from iGBS were estimated. 37 100 children who recovered from iGBS (14 600-96 200) were predicted to develop moderate or severe NDI. 40 500 (21 500-66 200) maternal iGBS cases and 46 200 (20 300-111 300) GBS stillbirths were predicted in 2020. GBS colonisation was also estimated to be potentially associated with considerable numbers of preterm births.

INTERPRETATION

Our analysis provides a comprehensive assessment of the pregnancy-related GBS burden. The Bayesian approach enabled coherent propagation of uncertainty, which is considerable, notably regarding GBS-associated preterm births. Our findings on both the acute and long-term consequences of iGBS have public health implications for understanding the value of investment in maternal GBS immunisation and other preventive strategies.

FUNDING

Bill & Melinda Gates Foundation.

Synthetic Glycans to Improve Current Glycoconjugate Vaccines and Fight Antimicrobial Resistance

Antimicrobial resistance (AMR) is emerging as the next potential pandemic. Different microorganisms, including the bacteria Acinetobacter baumannii, Clostridioides difficile, Escherichia coli, Enterococcus faecium, Klebsiella pneumoniae, Neisseria gonorrhoeae, Pseudomonas aeruginosa, non-typhoidal Salmonella, and Staphylococcus aureus, and the fungus Candida auris, have been identified by the WHO and CDC as urgent or serious AMR threats. Others, such as group A and B Streptococci, are classified as concerning threats. Glycoconjugate vaccines have been demonstrated to be an efficacious and cost-effective measure to combat infections against Haemophilus influenzae, Neisseria meningitis, Streptococcus pneumoniae, and, more recently, Salmonella typhi. Recent times have seen enormous progress in methodologies for the assembly of complex glycans and glycoconjugates, with developments in synthetic, chemoenzymatic, and glycoengineering methodologies. This review analyzes the advancement of glycoconjugate vaccines based on synthetic carbohydrates to improve existing vaccines and identify novel candidates to combat AMR. Through this literature survey we built an overview of structure-immunogenicity relationships from available data and identify gaps and areas for further research to better exploit the peculiar role of carbohydrates as vaccine targets and create the next generation of synthetic carbohydrate-based vaccines.

Bacterial and Host Determinants of Group B Streptococcal Infection of the Neonate and Infant

Group B streptococci (GBS) are Gram-positive β-hemolytic bacteria that can cause serious and life-threatening infections in neonates manifesting as sepsis, pneumonia, meningitis, osteomyelitis, and/or septic arthritis. Invasive GBS infections in neonates in the first week of life are referred to as early-onset disease (EOD) and thought to be acquired by the fetus through exposure to GBS in utero or to vaginal fluids during birth. Late-onset disease (LOD) refers to invasive GBS infections between 7 and 89 days of life. LOD transmission routes are incompletely understood, but may include breast milk, household contacts, nosocomial, or community sources. Invasive GBS infections and particularly meningitis may result in significant neurodevelopmental injury and long-term disability that persists into childhood and adulthood. Globally, EOD and LOD occur in more than 300,000 neonates and infants annually, resulting in 90,000 infant deaths and leaving more than 10,000 infants with a lifelong disability. In this review, we discuss the clinical impact of invasive GBS neonatal infections and then summarize virulence and host factors that allow the bacteria to exploit the developing neonatal immune system and target organs. Specifically, we consider the mechanisms known to enable GBS invasion into the neonatal lung, blood vessels and brain. Understanding mechanisms of GBS invasion and pathogenesis relevant to infections in the neonate and infant may inform the development of therapeutics to prevent or mitigate injury, as well as improve risk stratification.

A group B Streptococcus alpha-like protein subunit vaccine induces functionally active antibodies in humans targeting homotypic and heterotypic strains

Maternal vaccination is a promising strategy for preventing neonatal disease caused by group B Streptococcus. The safety and immunogenicity of the prototype vaccine GBS-NN, a fusion protein consisting of the N-terminal domains of the alpha-like proteins (Alp) αC and Rib, were recently evaluated favorably in healthy adult women in a phase 1 trial. Here we demonstrate robust immunoglobulin G (IgG) and immunoglobulin A (IgA) responses against αC and Rib, as well as against the heterotypic Alp family members Alp1–Alp3. IgA and heterotypic IgG responses are more variable between subjects and correlate with pre-existing immunity. Vaccine-induced IgG mediates opsonophagocytic killing and prevents bacterial invasion of epithelial cells. Like the vaccine-induced response, naturally acquired IgG against the vaccine domains is dominated by IgG1. Consistent with the high IgG1 cross-placental transfer rate, naturally acquired IgG against both domains reaches higher concentrations in neonatal than maternal blood, as assessed in a separate group of non-vaccinated pregnant women and their babies.

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GBS-NN subunit vaccine broadly elicits IgG1 to homotypic αC and Rib N-terminal domains

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IgA and heterotypic IgG responses occur in vaccinees with pre-existing immunity

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Abs mediate opsonophagocytic killing and prevent bacterial epithelial cell invasion

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IgG against αC-N and Rib-N is transferred efficiently across the placenta

Every Country, Every Family: Time to Act for Group B Streptococcal Disease Worldwide

The global burden of Group B Streptococcus (GBS) was estimated for 2015 prompting inclusion of GBS as a priority in the Global Meningitis Roadmap. New estimates for the year 2020 and a WHO report analysing the full value of GBS maternal vaccines has been launched to advance evidence based decision making for multiple stakeholders. In this first of a 10-article supplement, we discuss the following (1) gaps in evidence and action, (2) new evidence in this supplement, and (3) what actions can be taken now and key research gaps ahead. We call for investment in the research pipeline, notably description, development, and delivery, in order to accelerate progress and address the large burden of GBS for every family in every country.

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 CHROMagar^TM 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.

Evaluation of the Revogene® GBS DS assay performance for the intrapartum screening of group B streptococcus in comparison with intrapartum culture

Prevention of perinatal Group B Streptococcus (GBS) transmission is crucial in our effort to prevent Early-onset GBS disease. Here, we established the performance of the Revogene GBS DS assay for the detection of group B streptococcus on intrapartum vaginal samples in a laboratory environment using a prospective noninterventional study design. Intrapartum vaginal swabs were enriched using a selective culture method which served as study reference method. Overall, 119 patients were enrolled with an antenatal and intrapartum Group B Streptococcus colonization prevalence of 12.9% and 11.8%, respectively. Compared to intrapartum culture, the Revogene GBS DS assay had a sensitivity of 92.9% and a specificity of 99.1%, while the antenatal culture displayed a sensitivity 78.6% of and specificity of 96.2%. The Revogene GBS DS assay displayed an acceptable performance according to the European Group B Streptococcus consensus recommendations. Complementary studies in clinical practice are needed to confirm these findings.

Serotype distribution and incidence of invasive early onset and late onset group B streptococcal disease amongst infants in Singapore

Background

The current group B streptococcal (GBS) preventive measures had reduced invasive GBS early onset disease (EOD) incidences worldwide, but the late onset disease (LOD) incidences had remained unchanged. Administration of a safe and effective GBS vaccine in addition to the current strategies were thought to be the next steps in reducing the incidences of invasive GBS infection especially LOD. In this study, we aimed to examine the causative GBS serotypes in invasive GBS disease, determine the incidences of EOD and LOD, and compare the risk factors between EOD and LOD.

Methods

A retrospective study of infants ≤ 90-day-old over an 8-year period (2010–2017). The incidences of EOD and LOD were obtained by using patients with EOD and LOD who were born in our institution as the numerator and the live births in our institution per year of the study period as the denominator. Available GBS isolates were serotyped by the National Public Health Laboratory using capsular serotyping methods. The risk factors of EOD and LOD were compared.

Results

A total of 71 infants were identified; 16 (22.5%) and 55 (77.5%) of them had EOD and LOD, respectively. Serotype III (n = 42, 71.2%) was the most common serotype amongst the 59 isolates available for serotyping. Serotypes Ia, Ib, II, III, and V accounted for 98.3% (n = 58) of the invasive GBS diseases. The overall incidence was 0.42 per 1000 live births. The mean incidences of EOD and LOD were 0.13 per 1000 live births and 0.29 per 1000 live births, respectively. On multivariate analysis, risk factors for LOD as compared to EOD were: Chinese ethnicity (OR 27.1, 95% CI 3.0–243.1, p = 0.003) and negative/unknown maternal GBS status (OR 20.0, 95% CI 2.0–250.0, p = 0.012). Prematurity and intrapartum risk factors (peripartum maternal pyrexia, prolonged rupture of membrane) of EOD were not associated with LOD.

Conclusions

The LOD incidence had remained higher than EOD incidence in our cohort. A GBS vaccine that covers the major causative serotypes found in our cohort can potentially reduce the overall GBS disease burden in the country.

Probiotic interventions to reduce antepartum Group B streptococcus colonization: A systematic review and meta-analysis

OBJECTIVE

To systematically review and meta-analyse studies of the efficacy of probiotics to reduce antenatal Group B Streptococcus (GBS) colonisation.

PARTICIPANTS

Antenatal participants with known positive GBS colonisation or unknown GBS status.

INTERVENTION

Probiotic interventions containing species of Lactobacillus or Streptococcus.

DESIGN

Systematic review and meta-analysis.

MEASUREMENTS AND FINDINGS

The systematic review included 10 studies. Five articles contained in vitro studies of probiotic interventions to determine antagonistic activity against GBS. Six clinical trials of probiotics to reduce antenatal GBS were systematically reviewed and meta-analysed. The meta-analysis revealed that the use of an antenatal probiotic increased the probability of a negative GBS result by 79% (OR = 0.56, 95% CI = 8.7%, 194.1%, p = 0.02) (n = 709). However, only one clinical trial of 6 had a low risk of bias.

KEY CONCLUSIONS

The probiotic interventions subjected to in vitro testing showed antagonistic activity against GBS through the mechanisms of acidification, immune modulation, and adhesion. The findings of the meta-analysis of the clinical trials revealed that probiotics are a moderately effective intervention to reduce antenatal GBS colonisation. More well-controlled trials with diverse participants and with better elucidation of variables influencing GBS colonisation rates are needed.

IMPLICATIONS FOR PRACTICE

Probiotic interventions appear to be a safe and effective primary prevention strategy for antenatal GBS colonisation. Application of this low-risk intervention needs more study but may reduce the need for intrapartum antibiotic prophylaxis in countries or regions where antenatal GBS screening is used. Midwives can be instrumental in conducting and supporting larger well-controlled clinical trials.

Development and Immunogenicity of a Prototype Multivalent Group B Streptococcus Bioconjugate Vaccine

Group B Streptococcus (GBS) is a leading cause of neonatal infections and invasive diseases in nonpregnant adults worldwide. Developing a protective conjugate vaccine targeting the capsule of GBS has been pursued for more than 30 years; however, it has yet to yield a licensed product. In this study, we present a novel bioconjugation platform for producing a prototype multivalent GBS conjugate vaccine and its subsequent analytical and immunological characterizations. Using a glycoengineering strategy, we generated strains of Escherichia coli that recombinantly express the type Ia, type Ib, and type III GBS capsular polysaccharides. We then combined the type Ia-, Ib-, and III-capsule-expressing E. coli strains with an engineered Pseudomonas aeruginosa exotoxin A (EPA) carrier protein and the PglS oligosaccharyltransferase. Coexpression of a GBS capsule, the engineered EPA protein, and PglS enabled the covalent attachment of the target GBS capsule to an engineered serine residue on EPA, all within the periplasm of E. coli. GBS bioconjugates were purified, analytically characterized, and evaluated for immunogenicity and functional antibody responses. This proof-of-concept study signifies the first step in the development of a next-generation multivalent GBS bioconjugate vaccine, which was validated by the production of conjugates that are able to elicit functional antibodies directed against the GBS capsule.

Analysis of Susceptibility to the Antimicrobial and Anti-Biofilm Activity of Human Milk Lactoferrin in Clinical Strains of Streptococcus agalactiae With Diverse Capsular and Sequence Types

Group B Streptococcus (GBS) is one of the leading infection-related causes of adverse maternal and neonatal outcomes. This includes chorioamnionitis, which leads to preterm ruptures of membranes and can ultimately result in preterm or stillbirth. Infection can also lead to maternal and neonatal sepsis that may contribute to mortality. Currently, treatment for GBS infection include a bolus of intrapartum antibiotic prophylaxis to mothers testing positive for GBS colonization during late pregnancy. Lactoferrin is an antimicrobial peptide expressed in human breast milk, mucosal epithelia, and secondary granules of neutrophils. We previously demonstrated that lactoferrin possesses antimicrobial and antibiofilm properties against several strains of GBS. This is largely due to the ability of lactoferrin to bind and sequester iron. We expanded upon that study by assessing the effects of purified human breast milk lactoferrin against a panel of phenotypically and genetically diverse isolates of GBS. Of the 25 GBS isolates screened, lactoferrin reduced bacterial growth in 14 and biofilm formation in 21 strains. Stratifying the data, we observed that colonizing strains were more susceptible to the growth inhibition activity of lactoferrin than invasive isolates at lactoferrin concentrations between 250-750 µg/mL. Treatment with 750 µg/mL of lactoferrin resulted in differences in bacterial growth and biofilm formation between discrete sequence types. Differences in bacterial growth were also observed between capsular serotypes 1a and III. Maternally isolated strains were more susceptible to lactoferrin with respect to bacterial growth, but not biofilm formation, compared to neonatal sepsis isolates. Finally, high biofilm forming GBS strains were more impacted by lactoferrin across all isolates tested. Taken together, this study demonstrates that lactoferrin possesses antimicrobial and antibiofilm properties against a wide range of GBS isolates, with maternally isolated colonizing strains being the most susceptible.

Bacterial and Host Determinants of Group B Streptococcal Vaginal Colonization and Ascending Infection in Pregnancy

Group B streptococcus (GBS) is a gram-positive bacteria that asymptomatically colonizes the vaginal tract. However, during pregnancy maternal GBS colonization greatly predisposes the mother and baby to a wide range of adverse outcomes, including preterm birth (PTB), stillbirth, and neonatal infection. Although many mechanisms involved in GBS pathogenesis are partially elucidated, there is currently no approved GBS vaccine. The development of a safe and effective vaccine that can be administered during or prior to pregnancy remains a principal objective in the field, because current antibiotic-based therapeutic strategies do not eliminate all cases of invasive GBS infections. Herein, we review our understanding of GBS disease pathogenesis at the maternal-fetal interface with a focus on the bacterial virulence factors and host defenses that modulate the outcome of infection. We follow GBS along its path from an asymptomatic colonizer of the vagina to an invasive pathogen at the maternal-fetal interface, noting factors critical for vaginal colonization, ascending infection, and vertical transmission to the fetus. Finally, at each stage of infection we emphasize important host-pathogen interactions, which, if targeted therapeutically, may help to reduce the global burden of GBS.

Assessing the added value of group B Streptococcus maternal immunisation in preventing maternal infection and fetal harm: population surveillance study

OBJECTIVE

To assess the incidence of maternal group B Streptococcus (GBS) infection in England.

DESIGN

Population surveillance augmented through data linkage.

SETTING

England.

POPULATION

All pregnant women accessing the National Health Service (NHS) in England.

METHODS

Invasive GBS (iGBS) infections during pregnancy or within 6 weeks of childbirth were identified by linking Public Health England (PHE) national microbiology surveillance data for 2014 to NHS hospital admission records. Capsular serotypes of GBS were determined by reference laboratory typing of clinical isolates from women aged 15-44 years. Post-caesarean section surgical site infection (SSI) caused by GBS was identified in 21 hospitals participating in PHE SSI surveillance (2009-2015).

MAIN OUTCOME MEASURES

iGBS rate per 1000 maternities; risk of GBS SSI per 1000 caesarean sections.

RESULTS

Of 1601 patients diagnosed with iGBS infections in England in 2014, 185 (12%) were identified as maternal infections, a rate of 0.29 (95% CI 0.25-0.33) per 1000 maternities and representing 83% of all iGBS cases in women aged 18-44 years. Seven (3.8%) were associated with miscarriage. Fetal outcome identified excess rates of stillbirth (3.4 versus 0.5%) and extreme prematurity (<28 weeks of gestation, 3.7 versus 0.5%) compared with national averages (P < 0.001). Caesarean section surveillance in 27 860 women (21 hospitals) identified 47 cases of GBS SSI, with an estimated 4.24 (3.51-5.07) per 1000 caesarean sections, a median time-to-onset of 10 days (IQR 7-13 days) and ten infections that required readmission. Capsular serotype analysis identified a diverse array of strains with serotype III as the most common (43%).

CONCLUSIONS

Our assessment of maternal GBS infection in England indicates the potential additional benefit of GBS vaccination in preventing adverse maternal and fetal outcomes.

Downregulation of Ribosomal Contents and Kinase Activities Is Associated with the Inhibitive Effect on the Growth of Group B Streptococcus Induced by Placental Extracellular Vesicles

BACKGROUND

Like many other cell types, the human placenta produces large amounts of extracellular vesicles (EVs). Increasing evidence has shown that placental EVs contribute to the regulation of maternal immune and vascular systems during pregnancy via the transfer of their cargos. In this study, we investigated the effect of placental EVs on the growth of opportunistic pathogens that commonly colonise the female reproductive tract.

METHODS

Gram-positive bacterium Group B Streptococcus (GBS) and Gram-negative bacterium Escherichia coli (E. coli) were treated with placental EVs that were collected from placental explant cultures, and the growth, susceptibility, and resistance to antibiotics of the bacteria were measured. In addition, comparative proteomics analysis was also performed for the GBS with or without exposure to placental EVs.

RESULTS

When treated with placental micro-EVs or nano-EVs, the GBS growth curve entered the stationary phase earlier, compared to untreated GBS. Treatment with placental EVs also inhibited the growth of GBS on solid medium, compared to untreated GBS. However, these biological activities were not seen in E. coli. This attenuative effect required interaction of placental EVs with GBS but not phagocytosis. In addition, the susceptibility or resistance to antibiotics of GBS or E. coli was not directly affected by treatment with placental EVs. The proteomic and Western blotting analysis of GBS that had been treated with placental EVs suggested that the downregulation of cellular components and proteins associated with phosphorylation and cell energy in GBS may contribute to these attenuative effects.

CONCLUSION

We demonstrated the attenuative effect of the growth of GBS treated with placental EVs. Downregulation of cellular components and proteins associated with phosphorylation and cell energy may contribute to the physiological changes in GBS treated with placental EVs.