Group B streptococcal colonization in 160 mother-baby pairs: a prospective cohort study

Serotype distribution, antimicrobial resistance, and molecular characterization of group B Streptococcus isolates from Chinese pregnant woman

OBJECTIVE

This study was aimed to investigate the serotypes, antibiotic susceptibilities, and multi-locus sequence type (MLST) profiles of group B Streptococcus (GBS) in the Beijing area.

METHODS

Lower vaginal and rectal swabs were obtained from pregnant women of 35-37 gestational weeks (GWs) who attended the Beijing Obstetrics and Gynecology Hospital. All GBS isolates were identified with Gram staining, catalase reaction assays, and CAMP tests, followed by antibiotic susceptibility testing, serotype identification, multilocus sequence typing and erythromycin resistance gene analysis (ermB and mefE).

RESULTS

From July 2020 to June 2022, 311 (5.17%) of 6012 pregnant women that were screened for GBS colonization were detected positive. Of the eight serotypes identified (III, Ia, Ib, IV, II, VIII, V, and NT), serotypes III (43.09%), Ia (34.08%) and Ib (17.04%) were the predominant species. In the antimicrobial susceptibility experiments, the resistant rates measured for erythromycin, clindamycin, levofloxacin, and tetracycline were 76.21%, 63.99%, 50.80%, and 81.03%, respectively, and 7.6% of GBS isolates showed inducible clindamycin in resistance (D-test phenotype). Meanwhile, the multilocus sequence typing analysis showed that sequence type 19 (ST19) (30.34%) and ST10 (18.62%) were the dominant sequence types. Among the 237 erythromycin-resistant isolates, 176 harbored ermB (128, 54.00%) or mefE (48, 20.30%) gene alone.

CONCLUSION

The infection rates, serotypes or MSLT distribution, and antimicrobial resistance of GBS in Beijing area were investigated, which may be applied in analyses of the epidemiological characteristics of GBS. This contributes to the basic knowledge required for successful GBS vaccine development suited for disease prevention and treatment in China, as well as the implementation of effective clinical antimicrobials.

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.

Effect of probiotics on mother-to-neonate vertical transmission of group B streptococci: A prospective open-label randomized study

BACKGROUND

Group B Streptococci (GBS) are common vaginal bacteria found in 20-30% of pregnant women and a significant cause of invasive infections in newborns. Recently, attention has been focused on the efficacy of probiotics during the perinatal period. However, the effect of probiotic intake on the mother-to-child transmission (MTCT) of GBS remains unknown.

METHODS

Pregnant women with positive GBS results from vaginal and rectal swab cultures at 35-37 weeks of gestation were randomly assigned to the probiotic group or the control group in an open-label manner at the Department of Obstetrics and Gynecology, San-ikukai Hospital, Tokyo, Japan. The probiotic group received Lactobacillus reuteri during antenatal checkups from 35 to 37-week gestation to 1 month after delivery. Rectal swabs were obtained from the newborns at 5 days and at 1 month of age. Whole-genome sequencing was performed to test for GBS strains in the mother, whose newborn carried GBS at the 1-month checkup. Multi-locus sequence typing and single nucleotide polymorphism analyses were performed to identify MTCT.

RESULTS

Overall, 67 mother-infant pairs were included, with 31 in the probiotic group and 36 in the control group. The positivity rate of GBS in newborns at 1 month of age was 10% (n = 3) in the probiotic group and 28% (n = 10) in the control group. In newborns carrying GBS at 1 month of age, genetic analysis revealed that the MTCT rate was 6% in the probiotic group and 22% in the control group, although the difference was not statistically significant (p = 0.0927).

CONCLUSION

No statistically significant difference was found; however, the consumption of L. reuteri by women with GBS-positive pregnancies may inhibit the MTCT of GBS.

Neonatal Group B Streptococcus Disease

Group B Streptococcus (GBS) is an important cause of neonatal sepsis in term and preterm infants. Because GBS colonizes human genitourinary and gastrointestinal tracts, a significant focus of neonatal GBS disease prevention is to interrupt vertical transmission of GBS from mother to infant during parturition. Routine antepartum GBS screening in pregnant women, as well as widespread use of intrapartum antibiotic prophylaxis, have aided in overall reductions in neonatal GBS disease during the past 3 decades. However, neonatal GBS disease persists and may cause mortality and significant short- and long-term morbidity among survivors. Herein, we highlight contemporary epidemiology, microbial pathogenesis, and the clinical presentation spectrum associated with neonatal GBS disease. We summarize obstetric recommendations for antenatal GBS screening, indications for intrapartum antibiotic prophylaxis, and considerations for antibiotic selection. Finally, we review national guidelines for risk assessment and management of infants at risk for GBS disease.

Neonatal intestinal colonization of Streptococcus agalactiae and the multiple modes of protection limiting translocation

Streptococcus agalactiae, also known as Group B Streptococcus (GBS), is a predominant pathogen of neonatal sepsis, commonly associated with early-onset neonatal sepsis. GBS has also been associated with cases of late-onset sepsis potentially originating from the intestine. Previous findings have shown GBS can colonize the infant intestinal tract as part of the neonatal microbiota. To better understand GBS colonization dynamics in the neonatal intestine, we collected stool and milk samples from prematurely born neonates for identification of potential pathogens in the neonatal intestinal microbiota. GBS was present in approximately 10% of the cohort, and this colonization was not associated with maternal GBS status, delivery route, or gestational weight. Interestingly, we observed the relative abundance of GBS in the infant stool negatively correlated with maternal IgA concentration in matched maternal milk samples. Using a preclinical murine model of GBS infection, we report that both vertical transmission and direct oral introduction resulted in intestinal colonization of GBS; however, translocation beyond the intestine was limited. Finally, vaccination of dams prior to breeding induced strong immunoglobulin responses, including IgA responses, which were associated with reduced mortality and GBS intestinal colonization. Taken together, we show that maternal IgA may contribute to infant immunity by limiting the colonization of GBS in the intestine.

Late-Onset Group B Streptococcal Sepsis in Preterm Twins

Group B streptococcal (GBS) infection is one of the leading causes of neonatal sepsis worldwide. Despite a significant decline in early-onset (EOS) sepsis due to intrapartum antibiotic prophylaxis, the incidence of late-onset (LOS) infection has remained unchanged. However, LOS GBS sepsis affecting twins is very rare. We report on preterm twins born at 29 weeks of gestation: Twin B was 31 days old when he developed LOS GBS sepsis and meningitis, and Twin A was 35 days old when he developed LOS GBS sepsis. Tests for maternal GBS colonization in breast milk were negative. Both babies were treated with antibiotics and eventually discharged without complications.

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

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

The risk factors for Group B Streptococcus colonization during pregnancy and influences of intrapartum antibiotic prophylaxis on maternal and neonatal outcomes

BACKGROUND

Group B Streptococcus (GBS), also referred as Streptococcus agalactiae, is one of the leading causes of life-threatening invasive diseases such as bacteremia, meningitis, pneumonia and urinary tract infection in pregnant women and neonates. Rates of GBS colonization vary by regions, but large-sample studies on maternal GBS status are limited in southern China. As a result, the prevalence of GBS among pregnant women and its associated risk factors and the efficacy of intrapartum antibiotic prophylaxis (IAP) intervention in preventing adverse pregnancy and neonatal outcomes remain poorly understood in southern China.

METHODS

To fill this gap, we retrospectively analyzed demographic and obstetrical data of pregnant women who have undergone GBS screening and delivered between 2016 and 2018 in Xiamen, China. A total of 43,822 pregnant women were enrolled and only a few GBS-positive women did not receive IAP administration. Possible risk factors for GBS colonization were assayed by univariate and multivariate logistic regression analysis. Generalized linear regression model was applicated to analyze whether IAP is one of the impact factors of the hospital length of stay of the target women.

RESULTS

The overall GBS colonization rate was 13.47% (5902/43,822). Although women > 35 years old (P = 0.0363) and women with diabetes mellitus (DM, P = 0.001) had a higher prevalence of GBS colonization, the interaction between ages and GBS colonization was not statistically significant in Logistic Regression analysis (adjusted OR = 1.0014; 95% CI, 0.9950, 1.0077). The rate of multiple births was significantly dropped in GBS-positive group than that of GBS-negative group (P = 0.0145), with no significant difference in the rate of fetal reduction (P = 0.3304). Additionally, the modes of delivery and the incidences of abortion, premature delivery, premature rupture of membranes, abnormal amniotic fluid and puerperal infection were not significantly different between the two groups. The hospitalization stays of the subjects were not influenced by GBS infection. As for neonatal outcomes, the cases of fetal death in maternal GBS-positive group did not statistically differ from that in maternal GBS-negative group.

CONCLUSION

Our data identified that pregnant women with DM are at high risk of GBS infection and IAP is highly effective in prevention of adverse pregnancy and neonatal outcomes. This stressed the necessity of universal screening of maternal GBS status and IAP administration to the target population in China, and women with DM should be considered as priorities.

Global, regional, and national incidence and mortality of neonatal sepsis and other neonatal infections, 1990–2019

Background

Neonatal infections, especially neonatal sepsis, are one of the major causes of incidence and mortality in pediatrics. However, the global burden of neonatal sepsis and other neonatal infections (NSNIs) remains unclear.

Methods

From the 2019 global disease burden study, we collected annual incident cases, deaths, age-standardized incidence rates (ASIRs), and age-standardized deaths rates (ASDRs) of NSNIs in the past 30 years. Analysis indicators included the percentage of relative changes in incident cases and deaths, and the estimated annual percentage changes (EAPCs) of ASIRs and ASDRs. Correlations were assessed between the EAPCs of ASIRs and ASDRs and social evaluation indicators, including sociodemographic index (SDI) and universal health coverage index (UHCI).

Results

Globally, the number of incident cases of NSNIs grew by 12.79% per year, and the number of deaths dropped by 12.93% per year. During this period, global ASIR of NSNIs increased by 46% annually on average, while ASDR decreased by 53% annually on average. The ASIR and ASDR of female NSNIs were consistently lower than that of male NSNIs. The EAPC of female ASIR was 0.61, nearly twice that of male ASIR, and female ASIR was growing rapidly. The same declining trends of ASDR were noted in males and females. The ASIR of NSNIs in high-SDI regions grew by an average of 14% annually from 1990 to 2019. Except for high-SDI regions, the ASIRs of other 4 SDI regions maintained a rising trend at a high level, and were improved in the past 10 years. The ASDRs of all 5 SDI regions generally showed a downward trend. The region with the highest ASIR of NSNIs was Andean Latin America, and Western Sub-Saharan Africa had the highest mortality. We found a negative correlation between EAPCs of ASDRs and UHCI in 2019.

Conclusion

The global health situation was still not optimal. The incidence of NSNIs remained high, and continues to rise. The mortality of NSNIs has decreased, especially in the countries/territories with high UHCI. Therefore, it is crucial to improve the overall awareness and management of NSNIs, and take interventions for NSNIs worldwide.

Transmission of Group B Streptococcus in late-onset neonatal disease: a narrative review of current evidence

Group B streptococcus (GBS) late-onset disease (LOD, occurring from 7 through 89 days of life) is an important cause of sepsis and meningitis in infants. The pathogenesis and modes of transmission of LOD to neonates are yet to be elucidated. Established risk factors for the incidence of LOD include maternal GBS colonisation, young maternal age, preterm birth, HIV exposure and African ethnicity. The mucosal colonisation by GBS may be acquired perinatally or in the postpartum period from maternal or other sources. Growing evidence has demonstrated the predominant role of maternal sources in the transmission of LOD. Intrapartum antibiotic prophylaxis (IAP) to prevent early-onset disease reduces neonatal GBS colonisation during delivery; however, a significant proportion of IAP-exposed neonates born to GBS-carrier mothers acquire the pathogen at mucosal sites in the first weeks of life. GBS-infected breast milk, with or without presence of mastitis, is considered a potential vehicle for transmitting GBS. Furthermore, horizontal transmission is possible from nosocomial and other community sources. Although unfrequently reported, nosocomial transmission of GBS in the neonatal intensive care unit is probably less rare than is usually believed. GBS disease can sometime recur and is usually caused by the same GBS serotype that caused the primary infection. This review aims to discuss the dynamics of transmission of GBS in the neonatal LOD.

Clinical Risk Factors Associated With Late-Onset Invasive Group B Streptococcal Disease: Systematic Review and Meta-Analyses

BACKGROUND

Group B streptococcal (GBS) infection remains one of the most significant causes of late-onset sepsis and meningitis (LOGBS) among young infants. However, transmission routes and risk factors for LOGBS are not yet fully understood.

METHODS

We conducted systematic reviews on clinical risk factors previously reported in the literature (prematurity, low birth weight [<2500 g], antenatal colonization, multiple-gestation pregnancy, maternal age <20 years, male infant sex, intrapartum fever, prolonged rupture of membranes) and meta-analyses to determine pooled estimates of risk.

RESULTS

We included 27 articles, reporting 5315 cases. Prematurity (odds ratio [OR] 5.66; 95% confidence interval [CI]: 4.43-7.22), low birth weight (OR 6.73; 95% CI: 4.68-9.67), maternal colonization (2.67; [2.07-3.45]), and multiple-gestation pregnancies (OR 8.01; 95% CI: 5.19-12.38) were associated with an increased risk of LOGBS.

CONCLUSIONS

Prematurity/low birth weight and maternal colonization are major risk factors for LOGBS. Future GBS vaccine studies should try to establish the optimal time for vaccination during pregnancy to protect preterm infants.

Prevalence of Group B Streptococcus Recto-Vaginal Colonization, Vertical Transmission, and Antibiotic Susceptibility Among Pregnant Women in Ethiopia: A Systematic Review and Meta-Analysis

Background

Maternal Group B Streptococcus (GBS) recto-vaginal colonization is the most common route for early onset neonatal GBS diseases. A good understanding of the rate of maternal GBS colonization, vertical transmission rate, and antibiotic susceptibility profiles is needed to formulate a broad protection mechanism, like vaccine preparation. For that reason, this meta-analysis aimed at determining the pooled prevalence of GBS recto-vaginal colonization, vertical transmission rate, and antibiotic susceptibility profiles in Ethiopia.

Methods

Both published and unpublished studies were searched from MEDLINE/PubMed, CINAHL (EBSCO), Embase, Cochrane Library, SCOPUS, Web of Sciences databases, and Google Scholar. Independent selection was then carried out by the authors based on the eligibility criteria and data extraction using Microsoft excel. The authors then used STATA version 14.1 software for further cleaning and analysis. The review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses) PRISMA guidelines. Using the random-effect model, the prevalence with a 95% confidence interval (CI) and forest plot were used to present the findings. Besides, the studies' heterogeneity was assessed using Cochrane chi-square (I2) statistics, while Egger intercept was used to assess publication bias.

Results

This review included nineteen studies. The pooled prevalence of recto-vaginal colonization was 15% (95% CI: 11, 19), while the prevalence of vertical transmission was 51% (95% CI: 45, 58) and highest-level susceptibility to vancomycin was 99% (95% CI: 98, 100). However, the GBS susceptibility to tetracycline was 23% (95% CI: 9, 36).

Conclusions

Nearly one out of seven pregnant women in Ethiopia had recto-vaginal colonization of GBS. As a result, half of the pregnancies end with vertical transmission of GBS. Hence, the review emphasizes that policy and programs should consider planning and implementing prophylactic programs.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021287540.

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.

Group B Streptococcus colonisation, prevalence, associated risk factors and antimicrobial susceptibility pattern among pregnant women attending antenatal care at Dschang District Hospital, West Region of Cameroon: A hospital-based cross-sectional study

BACKGROUND

Group B Streptococcus (GBS), also known as Streptococcus agalactiae, is a Gram-positive bacterium known for its ability to colonise the vaginal and rectal areas of the mother and is a leading cause of neonatal mortality and morbidity. This study aimed at determining the prevalence, associated risk factors and antimicrobial susceptibility of GBS colonisation among pregnant women attending antenatal care (ANC) at Dschang District Hospital.

METHODS

This hospital-based cross-sectional study used a multistage sampling method to recruit a total of 621 consented pregnant women who attended ANC in Dchang District Hospital. The 621 Participants at 23.5 ± 6.4 weeks gestation each completed a questionnaire and vaginal swabs were collected for GBS analysis.

RESULTS

Among the 621 pregnant women that were included in this study, the colonisation rate of GBS was found to be 8.69%. Induced abortion (odds ratio [CI] = 3.09, 95% [1.56-6.21]), Spontaneous abortions (OR = 2.82, 95% CI 1.14-7.29), Stillbirth (OR [CI] = 7.75, 95% [2.61-21.71]), Fever (OR [CI] = 0.37, 95% [0.19-0.71]) and anaemia (OR [CI] = 0.22, 95% [0.12-0.43]) were found to be factors associated with GBS colonisation.

CONCLUSION

Our findings suggest that we found that, induce abortion, spontaneous abortions and stillbirths were highly associated rates of GBS colonisation, while fever and anaemia were associated with lower rates of GBS colonisation. Further longitudinal research is needed to establish the causal relationship and its biological mechanisms.

Group B streptococcus neonatal umbilical colonization managed by dry cord care in nurseries: A retrospective cohort study

BACKGROUND

Screening-based intrapartum antibiotic prophylaxis (IAP) has reduced the prevalence of early-onset group B Streptococcus (GBS) infection in newborns. Nevertheless, early-onset disease still occurs despite IAP, and IAP is not effective in preventing late-onset disease. This study aimed to determine the prevalence and risk factors of GBS neonatal umbilical colonization managed by dry cord care in Japan.

METHODS

Of 735 healthy newborns in the well-baby nursery at Saitama City Hospital, 353 from whom umbilical bacterial swabs were obtained before discharge were included in the analysis. Maternal and neonatal clinical characteristics were retrospectively reviewed.

RESULTS

GBS was detected in 4.2% (15/353) of umbilical swabs; 13/15 (86.8%) were born to GBS-negative mothers. The median (IQR) age at umbilical swab collection was 4.0 (4.0-5.0) days. Comparison of clinical characteristics between GBS-positive and negative neonates revealed a significant difference in the proportion of vaginal deliveries (15/15 [100%] in GBS-positive neonates vs. 115/338 [34.0%] in GBS-negative neonates, p < 0.0001). Of 15 GBS-positive neonates, 10 (66.7%) were also co-colonized with other enteric bacteria such as Escherichia coli.

CONCLUSION

Vaginal delivery was a risk factor associated with GBS neonatal umbilical colonization in Japanese neonates. Co-colonization with multiple enteric bacterial species implicates vertical transmission of GBS from undetected carrier mothers during passage through the birth canal.

An 18-year retrospective study on the epidemiology of early-onset neonatal sepsis - emergence of uncommon pathogens

BACKGROUND

Nationwide group B Streptococcus agalactiae (GBS) antepartum screening was instituted in Taiwan in 2012. The impact of the policy on early-onset sepsis (EOS) has not been evaluated. This study aimed to examine the impact of the policy on the incidence of neonatal EOS.

METHODS

This was a retrospective study conducted at MacKay Children's Hospital. Patients with culture-proven neonatal EOS were enrolled and divided by birth year in relation to the implementation of GBS prevention policy: Epoch 1, 2001-2004 pre-GBS screening; Epoch 2, 2005-2011 elective GBS screening; and Epoch 3, 2012-2018 universal GBS screening. The pathogens and antimicrobial resistance patterns were reviewed and analyzed. The incidence was modeled using Poisson regression.

RESULTS

A total of 128 neonates met the enrollment criteria. The observed incidence of EOS was 1.52‰. The incidence rates of EOS, GBS, and Escherichia coli (E. coli) sepsis were similar in Epoch 1 and Epoch 3. E. coli and non-Enterococcal group D Streptococcus (GDS) infection increased significantly in term infants, whereas the EOS-related mortality rate declined in preterm infants. Approximately 72% of the isolated E. coli were ampicillin-resistant, and the antimicrobial sensitivity remained unaltered during the studied period.

CONCLUSIONS

The overall EOS incidence has not changed from 2001 to 2018. However, changes in the causative pathogens were observed in both term and preterm infants. Clinicians should be aware of this evolving epidemiology to provide prompt appropriate perinatal management.

Breastfeeding and Risk of Late-Onset Group B Streptococcal Disease

BACKGROUND

Group B Streptococcus (GBS) is a major contributor to neonatal sepsis worldwide. Late-onset group B Streptococcus disease (LOGBS) and its risk factors remain poorly understood. The isolation of GBS from breast milk has been described in cases of LOGBS. This potential association has raised concerns for mothers and clinicians regarding the safety of ongoing breastfeeding. In this study, we aimed to investigate whether exposure to breast milk is associated with increased risk of LOGBS.

METHODS

A case-control study of LOGBS was conducted across 4 hospital networks in Victoria, Australia, including the 2 major tertiary pediatric centers in the state, to evaluate 11 years of data (2007-2017). Cases were captured initially from microbiology databases and recaptured with International Classification of Diseases discharge coding. Each case patient was matched with 4 controls to assess feeding status. Patients were matched for chronological age, gestation, discharge status, recruitment site, and calendar year.

RESULTS

We identified 92 cases of LOGBS: 73 cases on initial capture and 76 cases on the recapture analysis. Case patients were matched with 368 controls: 4 controls to each patient. Seventy-two patients were exposed to breast milk at the time of LOGBS (78.3%), compared with 274 controls (74.5%; odds ratio 1.2 [95% confidence interval 0.7-2.3]).

CONCLUSIONS

Breastfeeding was not associated with increased risk of LOGBS. Breast milk should not be tested for GBS during a first episode of LOGBS.

Understanding Factors in Group B Streptococcus Late-Onset Disease

Group B streptococcus (GBS) infection remains a leading cause of sepsis, pneumonia, and meningitis in infants. Rates of GBS early onset disease have declined following the widcespread use of intrapartum antibiotic prophylaxis; hence, late-onset infections (LOGBS) are currently a common presentation of neonatal GBS dicsease. The pathogenesis, mode of transmission, and risk factors associated with LOGBS are unclear, which interfere with effective prevention efforts. GBS may be transmitted from the mother to the infant at the time of delivery or during the postpartum period via contaminated breast milk, or as nosocomial or community-acquired infection. Maternal GBS colonization, prematurity, young maternal age, HIV exposure, and ethnicity (Black) are identified as risk factors for LOGBS disease; however, further studies are necessary to confirm additional risk factors, if any, for the implementation of effective prevention strategies. This narrative review discusses current and previous studies that have reported LOGBS. Few well-designed studies have described this condition; therefore, reliable assessment of maternal GBS colonization, breastfeeding, and twin delivery as risk factors for LOGBS remains limited.

Maternal Carriage in Late-Onset Group B Streptococcus Disease, Italy

At the time of late-onset disease, mothers often have positive breast milk culture or group B Streptococcus bacteriuria, suggesting heavy maternal colonization.

We retrospectively investigated mother-to-infant transmission of group B Streptococcus (GBS) in 98 cases of late-onset disease reported during 2007–2018 by a network in Italy. Mothers with full assessment of vaginal/rectal carriage tested at prenatal screening and at time of late onset (ATLO) were included. Thirty-three mothers (33.7%) were never GBS colonized; 65 (66.3%) were vaginal/rectal colonized, of which 36 (36.7%) were persistently colonized. Mothers with vaginal/rectal colonization ATLO had high rates of GBS bacteriuria (33.9%) and positive breast milk culture (27.5%). GBS strains from mother–infant pairs were serotype III and possessed the surface protein antigen Rib. All but 1 strain belonged to clonal complex 17. GBS strains from 4 mother–infant pairs were indistinguishable through pulsed-field gel electrophoresis. At least two thirds of late-onset cases are transmitted from mothers, who often have vaginal/rectal carriage, positive breast milk culture, or GBS bacteriuria, which suggests heavy maternal colonization.

Relationship between intrapartum antibiotic prophylaxis and group B streptococcal colonization dynamics in Japanese mother-neonate pairs

INTRODUCTION

In Japan, universal screening for group B streptococcal (GBS) colonization in pregnant women and intrapartum antibiotic prophylaxis (IAP) are recommended to prevent neonatal GBS infection. However, the dynamics of GBS colonization in Japanese mother/neonate pairs have not been adequately studied.

METHODS

A prospective cohort study was conducted from July 2018 to March 2019. Rectovaginal samples were collected from pregnant women (33-37 gestation weeks) once. In neonates, nasopharyngeal and rectal samples were collected at three time points: after birth, 1 week after birth, and 1 month after birth. All samples were analyzed for GBS using real-time PCR testing and culture methods. Capsular typing was performed for all GBS isolates and GBS-positive samples using real-time PCR testing.

RESULTS

The overall maternal and neonatal GBS-positivity rates were 22.7% (57/251) and 8.8% (22/251), respectively. IAP for GBS-positive mothers (96.5%) was highly administered. Eleven (19.3%) neonates born to GBS-positive mothers were GBS-positive, which was significantly higher than the 11 (5.7%) neonates born to GBS-negative mothers. The rate of GBS-positivity in neonates increased with an increased number of GBS colonies in mothers. More neonates were GBS-positive 1 month after birth than 1 week after birth, and there was a higher rate of GBS-positive rectal swabs than nasopharyngeal swabs. Capsular types of GBS that were isolated from each mother and neonate pair were the same, namely, Ib, III, V, and VI.

CONCLUSIONS

These findings indicate that the efficacy of IAP in preventing GBS transmission to neonates might be limited to within a few weeks after birth.

Invasive Group B Streptococcus Disease With Recurrence and in Multiples: Towards a Better Understanding of GBS Late-Onset Sepsis

Group B Streptococcus (GBS) is a common intestinal colonizer during the neonatal period, but also may cause late-onset sepsis or meningitis in up to 0.5% of otherwise healthy colonized infants after day 3 of life. Transmission routes and risk factors of this late-onset form of invasive GBS disease (iGBS) are not fully understood. Cases of iGBS with recurrence (n=25) and those occurring in parallel in twins/triplets (n=32) from the UK and Ireland (national surveillance study 2014/15) and from Germany and Switzerland (retrospective case collection) were analyzed to unravel shared (in affected multiples) or fixed (in recurrent disease) risk factors for GBS disease. The risk of iGBS among infants from multiple births was high (17%), if one infant had already developed GBS disease. The interval of onset of iGBS between siblings was 4.5 days and in recurrent cases 12.5 days. Disturbances of the individual microbiome, including persistence of infectious foci are suggested e.g. by high usage of perinatal antibiotics in mothers of affected multiples, and by the association of an increased risk of recurrence with a short term of antibiotics [aOR 4.2 (1.3-14.2), P=0.02]. Identical GBS serotypes in both recurrent infections and concurrently infected multiples might indicate a failed microbiome integration of GBS strains that are generally regarded as commensals in healthy infants. The dynamics of recurrent GBS infections or concurrent infections in multiples suggest individual patterns of exposure and fluctuations in host immunity, causing failure of natural niche occupation.

Prevalence of group B streptococcal colonization in the healthy non-pregnant population: a systematic review and meta-analysis

BACKGROUND

Colonization and transmission precede invasive group B streptococcal (GBS) disease. Data on GBS colonization prevalence, detection methods and risk factors for carriage are relevant for vaccine development and to understand GBS pathogenesis.

OBJECTIVES

To evaluate GBS colonization prevalence after the first week of life in the healthy non-pregnant population.

DATA SOURCES

Pubmed/Medline, Embase, Latin American and Caribbean Health Sciences Literature, World Health Organization Library Information System, and Scopus. Search performed 12 January 2021 with search terms related to 'GBS' and 'colonization, epidemiology, prevalence or screening' without restrictions.

STUDY ELIGIBILITY CRITERIA

All studies that reported prevalence of GBS colonization (any site) in the healthy population.

PARTICIPANTS

All individuals (>6 days of age), with no indication of pregnancy, invasive disease or severe underlying immunological co-morbidities.

METHODS

Logit transformation and a random effects model (DerSimonian and Laird) were used to pool colonization estimates. Subgroup analysis and meta-regression on a priori determined subgroups were performed.

RESULTS

We included 98 studies with 43 112 participants. Our search identified 9309 studies of which 8831 were excluded based on title and abstract and 380 after reading the full text. Colonization rates varied considerably between studies (I² = 97%), which could be partly explained by differences in culture methods (R² = 27%), culture sites (R² = 24%), continent (R² = 10%) and participant's age (R² = 6%). Higher prevalence was found with selective culture methods (19%, 95% CI 16%-23% versus non-selective methods 8%, 95% CI 6%-9%; p < 0.0001). Colonization rates were highest in rectum (19%, 95% CI 15%-24%), vagina (14%, 95% CI 12%-17%) and urethra (9%, 95% CI 5%-18%). In participants with negative rectal cultures, 7% (95% CI 5%-9%) had GBS cultured from another niche. Colonization prevalence was lower in children (6 months to 16 years; 3%, 95% CI 2%-5%) compared with adults (16%, 95% CI 14%-20%; p < 0.0001). Using selective culture methods in adults resulted in a prevalence of 26% (95% CI 19%-33%) rectal, 21% (95% CI 17%-25%) vaginal and 9% (95% CI 6%-14%) urethral colonization.

CONCLUSION

The rectum is the most common body site colonized by GBS. The best approach to screen for any GBS colonization is to screen multiple body sites using selective culture methods.

Updated Guidance: Prevention and Management of Perinatal Group B Streptococcus Infection

Group B Streptococcus (GBS) remains the most common cause of neonatal early-onset sepsis among term infants and a major cause of late-onset sepsis among both term and preterm infants. The American Academy of Pediatrics and the American College of Obstetricians and Gynecologists published separate but aligned guidelines in 2019 and 2020 for the prevention and management of perinatal GBS disease. Together, these replace prior consensus guidelines provided by the Centers for Disease Control and Prevention. Maternal intrapartum antibiotic prophylaxis based on antenatal screening for GBS colonization remains the primary recommended approach to prevent perinatal GBS disease, though the optimal window for screening is changed to 36 0/7 to 37 6/7 weeks of gestation rather than beginning at 35 0/7 weeks' gestation. Penicillin, ampicillin, or cefazolin are recommended for prophylaxis, with clindamycin and vancomycin reserved for cases of significant maternal penicillin allergy. Pregnant women with a history of penicillin allergy are now recommended to undergo skin testing, because confirmation of or delabeling from a penicillin allergy can provide both short- and long-term health benefits. Aligned with the American Academy of Pediatrics recommendations for evaluating newborns for all causes of early-onset sepsis, separate consideration should be given to infants born at less than 35 weeks' and more than or equal to 35 weeks' gestation when performing GBS risk assessment. Empiric antibiotics are recommended for infants at high risk for GBS early-onset disease. Although intrapartum antibiotic prophylaxis is effective in preventing GBS early-onset disease, currently there is no approach for the prevention of GBS late-onset disease.

Neonatal sepsis: within and beyond China

Sepsis remains a significant cause of neonatal morbidity and mortality in China. A better understanding of neonatal sepsis in China as compared with other industrialized and non-industrialized countries may help optimize neonatal health care both regionally and globally. Literature cited in this review was retrieved from PubMed using the keywords "neonatal sepsis," "early-onset (EOS)" and "late-onset (LOS)" in English, with the focus set on population-based studies. This review provides an updated summary regarding the epidemiology, pathogen profile, infectious work-up, and empirical treatment of neonatal sepsis within and beyond China. The incidence of neonatal EOS and the proportion of Group B Streptococcus (GBS) within pathogens causing EOS in China seem to differ from those in developed countries, possibly due to different population characteristics and intrapartum/postnatal health care strategies. Whether to adopt GBS screening and intrapartum antibiotic prophylaxis in China remains highly debatable. The pathogen profile of LOS in China was shown to be similar to other countries. However, viruses as potential pathogens of neonatal LOS have been underappreciated. Growing antimicrobial resistance in China reflects limitations in adapting antibiotic regimen to local microbial profile and timely cessation of treatment in non-proven bacterial infections. This review stresses that the local epidemiology of neonatal sepsis should be closely monitored in each institution. A prompt and adequate infectious work-up is critically important in diagnosing neonatal sepsis. Adequate and appropriate antibiotic strategies must be overemphasized to prevent the emergence of multi-resistant bacteria in China.

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

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

Group B streptococcal transmission rates as determined by PCR

Background Group B Streptococcus (GBS) is a common cause of neonatal sepsis. GBS colonization of the newborn gastrointestinal tract (GIT) may be a critical precursor for late-onset infection. Assessment of the rate of neonatal GBS intestinal colonization has generally relied upon culture-based methods. We used polymerase chain reaction (PCR) and culture to determine the rate of GBS transmission to neonates. We hypothesized that PCR may enhance the detection of neonatal GBS colonization of the GIT, and that the rate will be higher when evaluated with PCR as compared to culture. Methods This was a cross-sectional study, in which mothers who were positive for GBS on routine screening and their healthy infants were eligible for recruitment. Newborn stool was collected after 24 h of life and before hospital discharge, and stored at -80°C for culture and PCR targeting the GBS-specific surface immunogenic protein (sip) gene. Results A total of 94 mother-infant pairs were enrolled; of these pairs, stool was collected from 83 infants. Based on PCR, the overall GBS transmission rate was 3.6% (3/83). The transmission rate was 2.4% (1/41) among vaginal deliveries and 4.8% (2/42) among cesarean deliveries. The results of culture-based transmission detection were identical. Conclusion These results indicate that the rate of GBS transmission is low and that detection may not be enhanced by PCR methods.

Management of Infants at Risk for Group B Streptococcal Disease

Group B streptococcal (GBS) infection remains the most common cause of neonatal early-onset sepsis and a significant cause of late-onset sepsis among young infants. Administration of intrapartum antibiotic prophylaxis is the only currently available effective strategy for the prevention of perinatal GBS early-onset disease, and there is no effective approach for the prevention of late-onset disease. The American Academy of Pediatrics joins with the American College of Obstetricians and Gynecologists to reaffirm the use of universal antenatal microbiologic-based testing for the detection of maternal GBS colonization to facilitate appropriate administration of intrapartum antibiotic prophylaxis. The purpose of this clinical report is to provide neonatal clinicians with updated information regarding the epidemiology of GBS disease as well current recommendations for the evaluation of newborn infants at risk for GBS disease and for treatment of those with confirmed GBS infection. This clinical report is endorsed by the American College of Obstetricians and Gynecologists (ACOG), July 2019, and should be construed as ACOG clinical guidance.

Drugs for the Prevention and Treatment of Sepsis in the Newborn

Antimicrobial medications are the most commonly used medications in the neonatal intensive care unit. Antibiotics are used for infection prophylaxis, empiric treatment, and definitive treatment of confirmed infection. The choice of medication should be informed by the epidemiology and microbiology of infection in specific clinical scenarios and by the clinical condition of the infant. Understanding evolving pathogen susceptibility to antimicrobials and key pharmacotherapy determinants in neonates can inform optimal antibiotic use.

Group B streptococcus colonisation and associated risk factors among pregnant women: A hospital-based study and implications for primary care

BACKGROUND

Group B streptococcus (GBS), which asymptomatically colonises the vaginal and rectal areas of women, is a leading cause of neonatal mortality and morbidity. This study aimed to determine the prevalence and factors associated with GBS colonisation among pregnant women in Shenzhen, China.

METHODS

A hospital-based cross-sectional survey was conducted, using a multistage sampling method. Pregnant women at ≥28 weeks' gestation completed a questionnaire and vaginal swabs were obtained for GBS analysis. Data were analysed by chi-squared tests and logistic regression models.

RESULTS

The colonisation rate of GBS among pregnant women was 4.9%. The influencing factors associated with GBS colonisation included body mass index before pregnancy (odds ratio [OR] = 3.79, 95% CI 1.28-11.26), gestational age (OR = 5.81, 95% CI 1.20-28.15), induced abortion (OR = 0.63, 95% CI 0.40-0.98) and lotion use before pregnancy (OR = 1.59, 95% CI 1.04-2.44).

CONCLUSIONS

Our findings suggest that obesity, gestational age, induced abortion and lotion use were significantly associated with GBS colonisation. Further longitudinal research is needed to establish the causal relationship and its biological mechanisms.

Repertoire of human breast and milk microbiota: a systematic review

Breastfeeding is a major determinant of human health. Breast milk is not sterile and ecological large-scale sequencing methods have revealed an unsuspected microbial diversity that plays an important role. However, microbiological analysis at the species level has been neglected while it is a prerequisite before understanding which microbe is associated with symbiosis or dysbiosis, and health or disease. We review the currently known bacterial repertoire from the human breast and milk microbiota using a semiautomated strategy. Total 242 articles from 38 countries, 11,124 women and 15,489 samples were included. Total 820 species were identified mainly composed of Proteobacteria and Firmicutes. We report variations according to the analytical method (culture or molecular method), the anatomical site (breast, colostrum or milk) and the infectious status (healthy control, mastitis, breast abscess, neonatal infection). In addition, we compared it with the other human repertoires. Finally, we discuss its putative origin and role in health and disease.

Risk Factors for Infant Colonization by Hypervirulent CC17 Group B Streptococcus: Toward the Understanding of Late-onset Disease

The hypervirulent group B Streptococcus clone CC17 accounts for the majority of infant late-onset disease (LOD). We provide evidence that the high incidence of CC17 in LOD is likely due to an enhanced post-delivery mother-to-infant transmission.

Maternal antibiotic prophylaxis affects Bifidobacterium spp. counts in the human milk, during the first week after delivery

Human milk is an important source of microorganisms for infant gut colonisation. Although the maternal antibiotic prophylaxis is an important strategy to prevent maternal/neonatal sepsis, it has to be investigated how it may affect the human milk microbiota, especially the genus Bifidobacterium, which has been associated to health benefits. Here, we investigated the impact of the maternal antibiotic prophylaxis on the human milk Bifidobacterium spp. and total bacteria counts, in the first week (short-term) and first month (medium-term) after delivery. Human milk samples were collected from 55 healthy lactating women recruited from the University Hospital of the University of São Paulo at days 7±3 and 30±4 after vaginal delivery. Twenty one volunteers had received maternal antibiotic prophylaxis (MAP group) and 34 had not received MAP (no-MAP group) during or after labour. Total DNA was isolated from milk samples, and the bacterial counts were estimated by quantitative PCR (qPCR). We found lower levels of Bifidobacterium in the MAP group in the first week after delivery (median = 2.1 vs 2.4 log of equivalent cells/ml of human milk, for MAP and no-MAP groups, respectively; P=0.01), although there were no statistical differences in total bacteria count. However, no differences were found in Bifidobacterium counts between the groups at day 30±4 (median = 2.5 vs 2.2 log of equivalent cells/ml of human milk, for MAP and no-MAP groups, respectively; P=0.50). Our results suggest that MAP has a significant impact on Bifidobacterium counts in human milk, reducing this population in the first week after delivery. However, throughout the first month after delivery, the Bifidobacterium counts tend to recover, reaching similar counts to those found in no-MAP group at day 30±4 after delivery.

Molecular Characteristics and Antimicrobial Resistance of Group B Streptococcus Strains Causing Invasive Disease in Neonates and Adults

We aimed to analyze the molecular characteristics, clonality and antimicrobial resistance profiles of group B streptococcus (GBS) isolates collected in Taiwan from invasive diseases and carriage. Multilocus sequence typing (MLST) was used to assess the genetic diversity of 225 GBS strains from neonates and adults with invasive GBS diseases. 100 GBS strains collected from colonized pregnant women during the same period were compared, and all strains were characterized for one of nine capsule genotypes. We also determined the susceptibilities of all GBS isolates to various antimicrobial agents. The most frequently identified serotypes that caused invasive disease in neonates were III (60.6%) and Ia (17.3%), whereas type VI (32.7%), Ib (19.4%), and V (19.4%) were the most common to cause invasive disease in adults. Serotype VI was the leading type that colonized pregnant women (35.0%). Twenty-six sequence types (STs) were identified, and 90.5% of GBS strains were represented by 6 STs. ST-17 and ST-1 were more prevalent in invasive diseases in neonates and adults, respectively. The majority of serotype III and VI isolates belonged to clonal complex (CC)-17 and CC-1, respectively. ST-17 strains were more likely to cause meningitis and late-onset disease than other strains. In addition, ST-12 and ST-17 GBS strains showed the highest rate of resistance to erythromycin and clindamycin (range: 75.8–100%). In conclusion, CC-17/type III and CC-1/type VI are the most important invasive pathogens in infants and non-pregnant adults in Taiwan, respectively. GBS genotypes vary between different age groups and geographical areas and should be considered during GBS vaccine development.

Two Overlapping Clusters of Group B Streptococcus Late-onset Disease in a Neonatal Intensive Care Unit

OBJECTIVES

Current predominant routes of group B Streptococcus (GBS) transmission in preterm neonates admitted to neonatal intensive care unit (NICU) are poorly defined. We report 2 overlapping clusters of GBS late-onset disease (LOD) from June to September 2015 in an Italian NICU.

METHODS

During the outbreak, possible sources of transmission (equipment, feeding bottles and breast pumps) were swabbed. Specimens from throat and rectum were collected on a weekly basis from all neonates admitted to NICU. Colonized or infected neonates had cohorting. Bacterial isolates were characterized by serologic and molecular typing methods.

RESULTS

GBS was isolated in 2 full-term and 7 preterm neonates. Strains belonged to serotype III, with 3 different sequence types (ST17, ST182 and ST19). Full-term neonates were colonized with GBS strains unrelated to the clusters (ST182 and ST19). Two distinct ST17 strains caused 2 clusters in preterm neonates: a first cluster with 1 case of LOD and a second, larger cluster with 6 LOD in 5 neonates (one of them had recurrence). ST17 strains were isolated from vaginorectal and milk samples of 2 mothers. Two preterm neonates had no evidence of colonization for weeks, until they presented with LOD.

CONCLUSIONS

Molecular analyses identified the presence of multiclonal GBS strains and 2 clusters of 7 cases of GBS-LOD. The dynamics of transmission of GBS within the NICU were complex. Breast milk was suspected to be one of the possible sources. In a research setting, the screening of GBS carrier mothers who deliver very preterm could contribute to the tracking of GBS transmission.

Risk factors for neonatal group B streptococcus vertical transmission: a prospective cohort study of 1815 mother-baby pairs

BACKGROUND

The potential factors associated with group B streptococcus (GBS) vertical transmission have not been studied in detail.

STUDY DESIGN

A prospective cohort study was conducted to recruit 1815 mother-neonate pairs for GBS analysis. Pearson's chi-squared tests and generalized linear models were used to explore the risk factors for neonatal GBS colonization.

RESULTS

The rate of GBS vertical transmission was 14.1%. GBS colonization in all neonates was significantly associated with maternal GBS colonization, mode of delivery, episiotomy, number of prenatal vaginal exams, parity, and hypertension. For neonates born to GBS-positive mothers, GBS vertical transmission was associated with the mode of delivery, episiotomy, and sexually transmitted diseases. For neonates born to GBS-negative mothers, neonatal GBS colonization was associated with the number of prenatal vaginal exams, parity, and hypertension.

CONCLUSION

These findings suggest the need for prenatal GBS screening for pregnant women and intrapartum antimicrobial prophylaxis for GBS-colonized women.

Group B streptococcus late-onset disease,contaminated breast milk and mothers persistently GBS negative: report of 3cases

Background

Human milk is fundamental for its nutritional properties and to protect newborns, but it is not sterile and can sometime transmit bacteria. Few anecdotal cases suggest that breast milk could be a possible source of group B Streptococcus (GBS) late onset disease, although the pathogenesis is not entirely understood.

Case presentation

We report 3 cases of GBS late onset disease in full-term newborns. Fresh breast milk cultures yielded GBS, but mothers of neonates had no signs of mastitis and remained persistently GBS negative at rectovaginal site.

Conclusions

Breast milk containing group B Streptococcus can be a risk factor for late onset disease. The persistent negative maternal GBS status supports the assumption that newborns, colonised in the throat, could be the initial source of GBS, while the mammary gland could act as a GBS replication site. It is unclear whether a low bacterial load may represent only contamination rather than true milk infection.

Vertical transmission of group B Streptococcus and associated factors among pregnant women: a cross-sectional study, Eastern Ethiopia

Background

Vertically transmitted group B Streptococcus (GBS) causes fetal and neonatal infections. However, there is limited information on the vertical transmission of GBS in low-income countries. This study, therefore, aimed to determine the rate of vertical transmission of GBS and associated factors among pregnant women in Eastern Ethiopia.

Subjects and methods

A cross-sectional, facility-based study was conducted among pregnant women in Harar town, Eastern Ethiopia, from June to October, 2016. GBS positivity of pregnant women was confirmed by culture of rectovaginal swab. Vertical transmission at birth was confirmed by culture on swabs taken from the ear canal, umbilicus, axilla, groin, and nose within 6 hours after birth. Prevalence ratio (PR) along with 95% CI was estimated to examine factors associated with vertical transmission using log binomial regression analysis.

Results

Out of 231 GBS-colonized pregnant women at delivery, 104 births were identified as GBS colonized with a vertical transmission rate of 45.02% and 95% CI: 38.49, 51.68. Of 104 vertical transmission cases, 65 (62.50%) received no intrapartum antibiotic prophylaxis (IAP), 28 (26.92%) received it <4 hours before delivery, and 11 (10.58%) received it ≥4 hours before delivery. Pre-labor rupture of membranes at term (PR: 1.93; 95% CI: 1.04, 3.57), prolonged rupture of the membrane ≥18 hours (PR: 1.76; 95% CI: 1.13, 2.74), intrapartum maternal fever (PR: 1.40; 95% CI: 1.13, 1.75), and IAP received ≥4 hours (PR: 0.17; 95% CI: 0.09, 0.30) were significantly associated with vertical transmission of GBS.

Conclusion

The magnitude of vertical transmission of GBS was very high. However, the rate of adequate IAP received by mothers was very low. Efforts need to be strengthened to screen pregnant women during antenatal care and IAP should be used as necessary. Furthermore, maternal vaccination may provide a feasible strategy to reduce the vertical transmission.

Neonatal colonization of group B Streptococcus in China: Prevalence, antimicrobial resistance, serotypes, and molecular characterization

BACKGROUND

Group B Streptococcus (GBS) remains a leading cause of neonatal mortality and morbidity. This study aimed to determine the prevalence, antimicrobial susceptibility, serotypes, and molecular characterization of GBS colonized in neonates.

METHODS

A cross-sectional study was conducted using a multistage sampling method. Swabs for GBS identification were taken from infants' ear, oral cavity, and umbilicus immediately after birth. All GBS isolates were tested for antimicrobial susceptibility, resistance genes, serotyping, multilocus sequence typing, and virulence genes.

RESULTS

Of the 1,814 neonates, 1.3% tested positive for GBS, with 66.7% tested as multidrug resistant. All GBS isolates were susceptible to penicillin, but rates of resistance to tetracycline and erythromycin were high (70.8%), with the predominant resistance genes being tetM and ermB. The predominant serotype was III, followed by Ia and Ib, and the most common genotypes were sequence type (ST) 19, ST10, and ST485. Notably, we found that ST19 and ST17 isolates were associated with serotype III, resistant to tetracycline, erythromycin, and clindamycin, and carrying ermB, tetM, and rib; ST10 and ST12 isolates were associated with serotype Ib, resistant to erythromycin and clindamycin, and carrying ermB and alphaC; and ST485 isolates were associated with serotype Ia and carrying mefA/E, tetM, and epsilon.

CONCLUSIONS

These findings indicate a high prevalence of multidrug-resistant GBS and specific phenotype-genotype combinations for GBS clones.

The controversial role of breast milk in GBS late-onset disease

Group B streptococcus (GBS) is one of the most common causes of neonatal sepsis and meningitis. Intra-partum antibiotic prophylaxis does not play a significant role in reducing the risk of GBS late-onset disease. One of the proposed mechanisms for GBS late-onset disease is infection through contaminated breast milk. Infants in whom breast milk is thought to be the source for GBS late-onset disease are more heavily colonised and reports suggest they have a higher recurrence rate compared to infants with other potential sources. There is no consensus whether the breast milk of mothers of infants with GBS late-onset disease, especially those with recurrent episodes, should be tested for GBS. In addition, recommendations differ on whether breast-feeding should be interrupted or breast milk pasteurised, or whether the mother and infant should be treated for colonisation. In this review we discuss these different approaches.

Group B Streptococcal Maternal Colonization and Neonatal Disease: Molecular Mechanisms and Preventative Approaches

Group B Streptococcus (GBS) colonizes the gastrointestinal and vaginal epithelium of a significant percentage of healthy women, with potential for ascending intrauterine infection or transmission during parturition, creating a risk of serious disease in the vulnerable newborn. This review highlights new insights on the bacterial virulence determinants, host immune responses, and microbiome interactions that underpin GBS vaginal colonization, the proximal step in newborn infectious disease pathogenesis. From the pathogen perspective, the function GBS adhesins and biofilms, β-hemolysin/cytolysin toxin, immune resistance factors, sialic acid mimicry, and two-component transcriptional regulatory systems are reviewed. From the host standpoint, pathogen recognition, cytokine responses, and the vaginal mucosal and placental immunity to the pathogen are detailed. Finally, the rationale, efficacy, and potential unintended consequences of current universal recommended intrapartum antibiotic prophylaxis are considered, with updates on new developments toward a GBS vaccine or alternative approaches to reducing vaginal colonization.

Codevelopment of Microbiota and Innate Immunity and the Risk for Group B Streptococcal Disease

The pathogenesis of neonatal late-onset sepsis (LOD), which manifests between the third day and the third month of life, remains poorly understood. Group B Streptococcus (GBS) is the most important cause of LOD in infants without underlying diseases or prematurity and the third most frequent cause of meningitis in the Western world. On the other hand, GBS is a common intestinal colonizer in infants. Accordingly, despite its adaption to the human lower gastrointestinal tract, GBS has retained its potential virulence and its transition from a commensal to a dangerous pathogen is unpredictable in the individual. Several cellular innate immune mechanisms, in particular Toll-like receptors, the inflammasome and the cGAS pathway, are engaged by GBS effectors like nucleic acids. These are likely to impact on the GBS-specific host resistance. Given the long evolution of streptococci as a normal constituent of the human microbiota, the emergence of GBS as the dominant neonatal sepsis cause just about 50 years ago is remarkable. It appears that intensive usage of tetracycline starting in the 1940s has been a selection advantage for the currently dominant GBS clones with superior adhesive and invasive properties. The historical replacement of Group A by Group B streptococci as a leading neonatal pathogen and the higher frequency of other β-hemolytic streptococci in areas with low GBS prevalence suggests the existence of a confined streptococcal niche, where locally competing streptococcal species are subject to environmental and immunological selection pressure. Thus, it seems pivotal to resolve neonatal innate immunity at mucous surfaces and its impact on microbiome composition and quality, i.e., genetic heterogeneity and metabolism, at the microanatomical level. Then, designer pro- and prebiotics, such as attenuated strains of GBS, and oligonucleotide priming of mucosal immunity may unfold their potential and facilitate adaptation of potentially hazardous streptococci as part of a beneficial local microbiome, which is stabilized by mucocutaneous innate immunity.

Effects of Intrapartum Antibiotic Prophylaxis on Neonatal Acquisition of Group B Streptococci

OBJECTIVES

To assess the incidence of colonization with group B streptococci (GBS) among neonates as influenced by maternal GBS carriage and intrapartum antibiotic prophylaxis (IAP).

STUDY DESIGN

Between October 2014 and May 2015, nasopharyngeal and rectal swab samples were collected from 730 neonates at 1 week and 1 month after birth. GBS and capsular serotype were identified by real-time polymerase chain reaction and by culture. IAP at delivery was determined retrospectively from hospital records.

RESULTS

Sixty-four neonates (8.8%) were GBS-positive by real-time polymerase chain reaction and culture. Among neonates born to mothers who were GBS carriers (n = 107), 94.4% (101/107) had maternal IAP; 19.6% nonetheless were GBS-positive, compared with 6.5% of neonates born to noncarrier mothers (P <.01). Among neonates born to mothers receiving IAP, more were positive only at 1 month of age than at both 1 week and 1 month. The frequency of GBS in neonates born to mothers receiving IAP was significantly lower than that in neonates born to mothers not receiving IAP (P <.05). Capsular serotypes V (25%) and III (23.4%) were common, followed by Ib (15.6%), Ia (14.1%), II (7.8%), IV (6.3%), nontypeable (4.7%), and VI and VIII (each 1.6%).

CONCLUSIONS

Delayed colonization with GBS occurs in infants born to GBS carrier mothers receiving IAP. GBS should be considered in all infants at 1 month after birth with signs of infection.

Group B Streptococcus among Pregnant Women and Newborns in Mirzapur, Bangladesh: Colonization, Vertical Transmission, and Serotype Distribution

Group B streptococcus (GBS) infection is a leading cause of death among newborns in developed countries. Data on the burden of GBS in Asian countries are lacking. This study aimed to understand (i) the rate of maternal rectovaginal GBS carriage, (ii) the rate of vertical transmission of GBS, as determined by culturing ear, umbilicus, and nasal swabs, and (iii) the distribution of GBS serotypes. This prospective observational study was conducted between September 2012 and November 2013 at Kumudini Women's Medical College Hospital, a secondary-level hospital in Mirzapur, Bangladesh. The study enrolled pregnant women who visited the outpatient clinic for antenatal care (ANC) and/or delivered a child in the inpatient department of Kumudini Women's Medical College Hospital and the babies born to those mothers. Among 1,151 enrolled pregnant women, 172 (15% [95% confidence interval [CI], 13 to 17%]) carried GBS; among 68 babies born to mothers with carriage, 26 (38% [95% CI, 27 to 51%]) had GBS on their body surfaces, indicating vertical transmission. Typing of the isolates (n = 172) identified all 10 GBS serotypes, most commonly types Ia (40% [69/172 isolates]), V (23% [40/172 isolates]), II (14% [24/172 isolates]), and III (12% [20/172 isolates]). This study shows that Bangladesh has all of the ingredients for invasive GBS disease, including colonization of mothers by invasive serotypes and vertical transmission to babies.

Neonatal Group B Streptococcus Infections: Prevention Strategies, Clinical and Microbiologic Characteristics in 7 Years of Surveillance

BACKGROUND

The characteristics of group B streptococcus (GBS) neonatal disease in a period of 7 years are reported.

METHODS

The estimation of the neonatal GBS disease risk and prevention strategies adopted at delivery in absence of national guidelines was evaluated by the analysis of 3501 questionnaires. Notification of 194 neonatal GBS infections was recorded. In addition, 115 strains from neonatal early-onset disease (EOD) and late-onset disease, respectively, plus 320 strains from pregnant women were analyzed by molecular typing methods and for antibiotic resistance.

RESULTS

Preterm deliveries, precipitous labor and GBS negatively screened mothers were the prominent causes for an inadequate or lack of intrapartum antibiotic prophylaxis and EOD occurrence. The superimposable serotype distribution of GBS strains from EOD and from antenatal screening confirmed the vertical transmission from mother to neonate as the cause of disease. On the contrary, late-onset disease was almost exclusively caused by the internationally diffused clonal complex 17. Erythromycin resistance was detected in 17% of strains. Resistance to clindamycin was 15.3 %.

CONCLUSIONS

The administration of intrapartum antibiotic prophylaxis to negatively GBS screened women in presence of risk factors was a deviation from the recommendations issued by the Centers for Disease Control and Prevention, and it should deserve further consideration. Routine surveillance and molecular typing of circulating clones are essential for the effective management of the neonatal GBS disease.

Risk factors for group B streptococcal disease in neonates of mothers with negative antenatal testing

OBJECTIVE

The aim of this study was to identify risk factors for early-onset group B Streptococcus (EOGBS) disease in neonates of mothers with negative antenatal screening.

STUDY DESIGN

We performed a retrospective cohort study of neonates born to mothers with negative antenatal GBS screening between 2002 and 2012. Our primary outcome was EOGBS infection. We used multivariable logistic regression to assess factors associated with EOGBS.

RESULTS

EOGBS was confirmed in 492 of the 179 818 neonates that met the study inclusion criteria. Risk factors for EOGBS included black race (reference: white, odds ratio (OR) =1.81 (95% confidence interval: 1.43, 2.31)), maternal age <18 years (reference: >35 years, OR=2.63 (1.54, 4.51)) and maternal age 18 to 35 years (reference: >35 years, OR=1.94 (1.30, 2.88)).

CONCLUSION

Maternal age <18 years and black race were the strongest predictors of EOGBS. Further research investigating contributors to the discordance between screening results and neonatal outcomes in these populations is needed.

Risk factors for Group B Streptococcus colonisation and disease in Gambian women and their infants

OBJECTIVES

To determine risk factors for GBS colonisation in Gambian mothers and in their infants from birth to day 60-89 of age.

METHODS

Swabs and breastmilk from mothers/infant pairs were collected and cultured on selective agar. Negative samples were analysed for GBS DNA via real-time PCR. Positive isolates were serotyped using multiplex PCR and gel-agarose electrophoresis.

RESULTS

Seven hundred and fifty women/infant pairs were recruited. 253 women (33.7%) were GBS-colonised at delivery. The predominant serotypes were: V (55%), II (16%), III (10%), Ia (8%) and Ib (8%). 186 infants were colonised (24.8%) at birth, 181 (24.1%) at 6 days and 96 at day 60-89 (14%). Infants born before 34 weeks of gestation and to women with rectovaginal and breastmilk colonisation at delivery had increased odds of GBS colonisation at birth. Season of birth was associated with increased odds of persistent infant GBS colonisation (dry season vs. wet season AOR 2.9; 95% CI 1.6-5.2).

CONCLUSION

GBS colonisation is common in Gambian women at delivery and in their infants to day 60-89 and is dominated by serotype V. In addition to maternal colonisation, breastmilk and season of birth are important risk factors for infant GBS colonisation.

Group B streptococcal infections in the newborn infant and the potential value of maternal vaccination

Group B Streptococcus (GBS) is a leading cause of neonatal bacterial infections in developed countries. Early-onset disease (EOD) occurs at day 0-6 and late-onset disease occurs at day 7-89. Currently, the prevention of EOD relies upon intrapartum antibiotic prophylaxis (IAP) given to women who are GBS positive at prenatal screening or women with risk factors for EOD. Although successfully implemented, IAP has not fully eradicated EOD, and incidence rates of late-onset disease remain unchanged. Furthermore, antibiotic resistance may result from widespread antibiotic use. New prophylactic strategies are therefore of critical importance. A vaccine active against GBS, administered during pregnancy and combined with targeted IAP, could overcome these problems and reduce the mortality and morbidity associated with invasive diseases.

Maternal group B Streptococcus and the infant gut microbiota

Early patterns of gut colonization may predispose children to adult disease. Exposures in utero and during delivery are associated with the infant gut microbiome. Although ~35% of women carry group B strep (GBS; Streptococcus agalactiae) during pregnancy, it is unknown if GBS presence influences the infant gut microbiome. As part of a population-based, general risk birth cohort, stool specimens were collected from infant's diapers at research visits conducted at ~1 and 6 months of age. Using the Illumina MiSeq (San Diego, CA) platform, the V4 region of the bacterial 16S rRNA gene was sequenced. Infant gut bacterial community compositional differences by maternal GBS status were evaluated using permutational multivariate analysis of variance. Individual operational taxonomic units (OTUs) were tested using a zero-inflated negative binomial model. Data on maternal GBS and infant gut microbiota from either 1 (n=112) or 6-month-old stool (n=150) specimens was available on 262 maternal-child pairs. Eighty women (30.5%) were GBS+, of who 58 (72.5%) were given intrapartum antibiotics. After adjusting for maternal race, prenatal antifungal use and intrapartum antibiotics, maternal GBS status was statistically significantly associated with gut bacterial composition in the 6 month visit specimen (Canberra R 2=0.008, P=0.008; Unweighted UniFrac R 2=0.010, P=0.011). Individual OTU tests revealed that infants of GBS+ mothers were significantly enriched for specific members of the Clostridiaceae, Ruminococcoceae, and Enterococcaceae in the 6 month specimens compared with infants of GBS- mothers. Whether these taxonomic differences in infant gut microbiota at 6 months lead to differential predisposition for adult disease requires additional study.