Uncertainties in Screening and Prevention of Group B Streptococcus Disease

Development and performance evaluation of a qPCR-based assay for the fully automated detection of group B Streptococcus (GBS) on the Panther Fusion Open Access system

Streptococcus agalactiae [group B Streptococcus (GBS)] poses a major threat as the primary cause of early-onset neonatal invasive disease, particularly when mothers are colonized rectovaginally. Although culture remains the gold standard for antepartum GBS screening, quantitative polymerase chain reaction (qPCR) offers advantages in terms of sensitivity and turnaround time. The aim of this study was to validate the clinical utility of an automated qPCR laboratory-developed test (LDT) for antepartum GBS screening using the Panther Fusion Open Access system (Hologic, California, USA). The LDT targeted a conserved region of the GBS surface immunogenic protein gene, demonstrating no cross-reactivity and high coverage (99.82%-99.99%). The limit of detection (LoD) was 118 CFU/mL. Comparison with commercial qPCR assays (Panther Fusion GBS and VIASURE Streptococcus B Real-Time) revealed an overall agreement of 99.7%, with a robust Cohen's kappa coefficient of 0.992. Testing of 285 rectovaginal swabs from pregnant women and 15 external quality assessment samples demonstrated exceptional diagnostic performance of the LDT, achieving a diagnostic sensitivity and specificity of 100%, underscoring its accuracy. Prevalence and predictive values were also determined to reinforce test reliability. Our research highlights the limitations of culture-based screening and supports the suitability of our qPCR-based LDT for GBS detection in a clinical setting.IMPORTANCERectovaginal colonization by GBS is a major risk factor for early-onset invasive neonatal disease. The most effective approach to reducing the incidence of early-onset disease (EOD) has been described as universal screening, involving assessment of GBS colonization status in late pregnancy and intrapartum antibiotic prophylaxis. Despite its turnaround time and sensitivity limitations, culture remains the gold standard method for GBS screening. However, nucleic acid amplification-based tests, such as qPCR, have been utilized due to their speed and high sensitivity and specificity. This study validated the clinical usefulness of an automated qPCR-LDT for antepartum GBS screening through the Panther Fusion Open Access system (Hologic). Our study addresses the critical need for more robust, sensitive, and rapid strategies for GBS screening in pregnant women that could favorably impact the incidence of EOD.

Evaluation of the Xpert Xpress GBS test for rapid detection of group B Streptococcus in pregnant women

IMPORTANCE

This was the first study evaluating the performance of the Xpert Xpress group B Streptococcus (GBS) test using rectovaginal swabs from Chinese pregnant women. Compared to the other three assays, the Xpert Xpress GBS test demonstrated high sensitivity and specificity when screening 939 pregnant women for GBS in rectovaginal specimens. Additionally, its reduced time to obtain results makes it valuable for the rapid detection of GBS.

Associations of intrapartum antibiotics and growth, atopy, gastrointestinal and sleep outcomes at one year of age

BACKGROUND

Studies investigating neonatal outcomes following intrapartum antibiotic exposure show conflicting results.

METHODS

Data were collected prospectively in pregnancy to 1-year-of-age, from 212 mother-infant pairs. Adjusted multivariable regression models estimated relationships following exposure to intrapartum antibiotics among vaginally-born, full-term infants and outcomes related to growth, atopic disease, gastrointestinal symptoms, and sleep at 1-year.

RESULTS

Intrapartum antibiotic exposure (n = 40) was not associated with mass, ponderal index, BMI z-score (1- year), lean mass index (5-months) or height. Antibiotic exposure in labour ≥4-h was associated with increase in fat mass index at 5-months (β 0.42 [95% CI: 0.03, 0.80], p = 0.03). Intrapartum antibiotic was associated with atopy in the first year (OR: 2.93 [95% CI: 1.34, 6.43], p = 0.007). Antibiotic exposure during intrapartum or day 1-7 was associated with newborn fungal infection requiring antifungal therapy (OR 3.04 [95% CI: 1.14, 8.10], p = 0.026), and number of fungal infections (IRR: 2.90 [95% CI: 1.02, 8.27], p = 0.046).

CONCLUSION

Intrapartum and early life exposure to antibiotics were independently associated with measures of growth, atopy, and fungal infections suggesting that intrapartum and early neonatal antibiotics be used prudently following careful risk-benefit analysis.

IMPACT

This prospective study: Shows a shift in fat mass index at 5 months associated with antibiotic administration ≥4 h in labour; an earlier age than previously reported; Shows atopy reported less frequently among those not exposed to intrapartum antibiotics; Supports earlier research of increased likelihood of fungal infection following exposure to intrapartum or early-life antibiotics; Adds to growing evidence that antibiotics used intrapartum and in early neonatal periods influence longer-term outcomes for infants. Suggests that use of intrapartum and early neonatal antibiotics should be used prudently after careful consideration of risk and benefit.

Considerations for post-licensure group B streptococcus vaccine effectiveness studies

Post‐licensure studies of a Group B streptococcal vaccines for pregnant women in low and middle‐income countries will require investment in electronic health records.

Antibiotic Sensitivity of Group B Streptococcus from Pregnant Mothers and Its Association with Resistance Genes

OBJECTIVE

This study assessed the antibiotic susceptibility and characterized antibiotic resistance genes of group B Streptococcus (GBS) isolates from selected tertiary care hospitals in Western Province, Sri Lanka.

METHODS

A descriptive cross-sectional study was carried out to determine antibiotic sensitivity of GBS among 175 pregnant women of >35 weeks of gestation attending antenatal clinics in four teaching hospitals. Low vaginal and rectal swabs were collected separately, and GBS was identified by standard microbiological methods. Antibiotic sensitivity and minimum inhibitory concentration (MIC) were performed according to Clinical and Laboratory Standards Institute (CLSI) guidelines. DNA was extracted from culture isolates, and antibiotic-resistant genes were identified by polymerase chain reaction using ermB, ermTR, mefA, and linB genes.

RESULTS

GBS colonization in the study sample was 25.7% (45/175) with detection rate of 22.9% (40/175) and 2.9% (5/175) in vaginal and rectal samples, respectively. All isolates were susceptible to penicillin with an MIC range of 0.03-0.12 μg/mL. Six isolates (13.3%) were intermediate, and 11 isolates (24.4%) were resistant to erythromycin. There were 5 intermediately resistant isolates (11.1%) and 10 resistant isolates (22.2%) for clindamycin. Of them, seven had inducible clindamycin resistance (iMLSB). MIC range of erythromycin was 0.03-0.32 μg/mL and that of clindamycin was 0.06-0.32 μg/mL. ermB gene was detected in 7 (15.5%). ermTR gene was found in 16 (35.6%) and was significantly associated with iMLSB phenotype (p = 0.005). mefA gene was detected in two (4.4%) isolates, while linB gene was not detected in tested isolates.

CONCLUSION

All isolates were sensitive to penicillin, and the most prevalent resistance genotype was ermTR in the study population.

Updates on Group B Streptococcus Infection in the Field of Obstetrics and Gynecology

Group B Streptococcus (GBS, Streptococcus agalactiae) is a Gram-positive bacterium that is commonly found in the gastrointestinal and urogenital tracts. However, its colonization during pregnancy is an important cause of maternal and neonatal morbidity and mortality worldwide. Herein, we specifically looked at GBS in relation to the field of Obstetrics (OB) along with the field of Gynecology (GY). In this review, based on the clinical significance of GBS in the field of OBGY, topics of how GBS is being detected, treated, and should be prevented are addressed.

Quantitative insights into effects of intrapartum antibiotics and birth mode on infant gut microbiota in relation to well-being during the first year of life

Birth mode and maternal intrapartum (IP) antibiotics affect infants' gut microbiota development, but their relative contribution to absolute bacterial abundances and infant health has not been studied. We compared the effects of Cesarean section (CS) delivery and IP antibiotics on infant gut microbiota development and well-being over the first year. We focused on 92 healthy infants born between gestational weeks 37-42 vaginally without antibiotics (N = 26), with IP penicillin (N = 13) or cephalosporin (N = 7) or by CS with IP cephalosporin (N = 33) or other antibiotics (N = 13). Composition and temporal development analysis of the gut microbiota concentrated on 5 time points during the first year of life using 16S rRNA gene amplicon sequencing, integrated with qPCR to obtain absolute abundance estimates. A mediation analysis was carried out to identify taxa linked to gastrointestinal function and discomfort (crying, defecation frequency, and signs of gastrointestinal symptoms), and birth interventions. Based on absolute abundance estimates, the depletion of Bacteroides spp. was found specifically in CS birth, while decreased bifidobacteria and increased Bacilli were common in CS birth and exposure to IP antibiotics in vaginal delivery. The abundances of numerous taxa differed between the birth modes among cephalosporin-exposed infants. Penicillin had a milder impact on the infant gut microbiota than cephalosporin. CS birth and maternal IP antibiotics had both specific and overlapping effects on infants' gut microbiota development. The resulting deviations in the gut microbiota are associated with increased defecation rate, flatulence, perceived stomach pain, and intensity of crying in infancy.

Retrospective Study for the Clinical Evaluation of a Real-Time PCR Assay with Lyophilized and Ready-to-Use Reagents for Streptococcus agalactiae Detection in Prenatal Screening Specimens

Streptococcus agalactiae is a leading cause of sepsis and meningitis in newborns and young infants. Screening programs and intrapartum antibiotic prophylaxis have reduced early neonatal onset of disease. The aim of this study was to evaluate a molecular assay with lyophilized and ready-to-use reagents: VIASURE® Streptococcus B Real Time PCR detection kit (CerTest Biotec) (Viasure qPCR assay) compared to both the GBS culture and a molecular assay with separated and frozen reagents: Strep B Real-TM Quant (Sacace Biotecnologies®) (Sacace qPCR assay). A total of 413 vaginal−rectal swabs from women between the 35th and 37th weeks of pregnancy were processed. GBS culture was firstly achieved through Granada medium and Columbia CNA agar at 35 °C in aerobic conditions. Then, nucleic acid extraction was performed for subsequent molecular analysis using both commercial assays. Discordant results were resolved via bidirectional Sanger sequencing. Viasure qPCR assay clinical sensitivity was 0.97 (0.92−0.99) and specificity 1 (0.98−1). This retrospective study demonstrated the good clinical parameters and the strong overall agreement (99.3%) between the Viasure qPCR assay and both reference assays. Finally, the added value observed of the assay under study was the stabilized and ready-to-use format, reducing the number of time-consuming steps, permitting the storage at room temperature, facilitating transport, being environmentally respectful, and reducing additional costs.

Group B Streptococcus (GBS) colonisation is dynamic over time, whilst GBS capsular polysaccharides-specific antibody remains stable

Group B Streptococcus (GBS) is a leading cause of adverse pregnancy outcomes due to invasive infection. This study investigated longitudinal variation in GBS rectovaginal colonization, serum and vaginal GBS capsular polysaccharide (CPS)-specific antibody levels. Non-pregnant women were recruited in the UK and were sampled every 2 weeks over a 12-week period. GBS isolates were taken from recto-vaginal swabs and serotyped by polymerase chain reaction. Serum and vaginal immunoglobulin G (IgG) and nasal immunoglobulin A (IgA) specific to CPS were measured by Luminex, and total IgG/A by ELISA. Seventy women were enrolled, of median age 26. Out of the 66 participants who completed at least three visits: 14/47 (29.8%) women that were GBS negative at screening became positive in follow-up visits and 16/19 (84.2%) women who were GBS positive at screening became negative. There was 50% probability of becoming negative 36 days after the first positive swab. The rate of detectable GBS carriage fluctuated over time, although serum, vaginal, and nasal CPS-specific antibody levels remained constant. Levels of CPS-specific antibodies were higher in the serum of individuals colonized with GBS than in non-colonized, but similar in the vaginal and nasal mucosa. We found correlations between antibody levels in serum and the vaginal and nasal mucosa. Our study demonstrates the feasibility of elution methods to retrieve vaginal and nasal antibodies, and the optimization of immunoassays to measure GBS-CPS-specific antibodies. The difference between the dynamics of colonization and antibody response is interesting and further investigation is required for vaccine development.

The Vaginal Microbiota Composition and Genital Infections during and after Pregnancy among Women in Pemba Island, Tanzania

We investigated the vaginal microbiota (VMB) composition, prevalence of genital pathogens and their association among pregnant and post-delivery women in Pemba Island, Tanzania. Vaginal swabs were collected from 90 women, at two time points during pregnancy (<20 weeks of gestational age [GA] and ≥20 weeks GA) and once after delivery, when possible. IS-pro assay was used for VMB characterization. Chlamydia trachomatis (CT), Neisseria gonorrhea (NG), Trichomonas vaginalis (TV), Mycoplasma genitalium (MG) and human papillomavirus (HPV) were detected by qPCRs. VMB were mostly Lactobacillus dominant during pregnancy and non-Lactobacillus dominant post-delivery. A significant decrease in VMB richness was observed during pregnancy among paired and unpaired samples. Shannon diversity was significantly lower during pregnancy than post-delivery among unpaired samples. Klebsiella species and Streptococcus anginosus were the most commonly identified pathobionts at all timepoints. A high abundance of pathobionts was mostly seen in women with non-Lactobacillus dominant VMB. At ≥20 weeks GA timepoint during pregnancy, 63.0% of the women carrying one or more genital pathogen (either HPV, CT, TV, or MG) had L. iners dominant VMB. NG was not detected pre-delivery. This study contributes evidence on VMB composition, its changes during pregnancy and post-delivery, and their association with pathobionts and genital pathogens.

Quality assessment of clinical practice guidelines for neonatal sepsis using the Appraisal of Guidelines for Research and Evaluation (AGREE) II Instrument: A systematic review of neonatal guidelines

BACKGROUND AND OBJECTIVE

Neonatal sepsis (NS) continues to be a critical healthcare priority for the coming decades worldwide. The aim of this study was to critically appraise the quality of recent clinical practice guidelines (CPGs) for neonatal sepsis and to summarize and compare their recommendations.

METHODS

This study involves a systematic review of CPGs. We identified clinical questions and eligibility criteria and searched and screened for CPGs using bibliographic and CPG databases and professional societies. Each included CPG was assessed by four independent appraisers using the Appraisal of Guidelines for REsearch & Evaluation II (AGREE II) instrument. We summarized the recommendations in a comparison practical table. The systematic review was drafted according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) statement. Its protocol was registered in the PROSPERO International Prospective Register of Systematic Reviews (ID: CRD42021258732).

RESULTS

Our search retrieved 4,432 citations; of which five CPGs were eligible and appraised: American Academy of Pediatrics (AAP 2018) (35 and 34 weeks); Canadian Pediatric Society (CPS 2017); National Institute for Health and Care Excellence (NICE 2021); and Queensland Maternity and Neonatal Services (QH 2020). Among these, the overall assessment of two evidence-based CPGs scored > 70% (NICE and QH), which was consistent with their higher scores in the six domains of the AGREE II instrument. In domain 3 (rigor of development), NICE and QH scored 99 and 60%, respectively. In domain 5 (applicability), they scored 96 and 74%, respectively, and in domain 6 (editorial independence), they scored 90 and 71%, respectively.

CONCLUSION

The methodological quality of the NICE CPG was superior followed by the QH CPG with relevant recommendations for use in practice.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021258732, PROSPERO (CRD42021258732).

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.

Intrapartum Group B Streptococcal Prophylaxis and Childhood Allergic Disorders

OBJECTIVES

To determine if maternal intrapartum group B Streptococcus (GBS) antibiotic prophylaxis is associated with increased risk of childhood asthma, eczema, food allergy, or allergic rhinitis.

METHODS

Retrospective cohort study of 14 046 children. GBS prophylaxis was defined as administration of intravenous penicillin, ampicillin, cefazolin, clindamycin, or vancomycin to the mother, ≥4 hours before delivery. Composite primary outcome was asthma, eczema, or food allergy diagnosis within 5 years of age, identified by diagnosis codes and appropriate medication prescription. Allergic rhinitis was defined by using diagnostic codes only and analyzed as a separate outcome. Analysis was a priori stratified by delivery mode and conducted by using Cox proportional hazards model adjusted for multiple confounders and covariates. Secondary analyses, restricted to children retained in cohort at 5 years' age, were conducted by using multivariate logistic regression.

RESULTS

GBS prophylaxis was not associated with increased incidence of composite outcome among infants delivered vaginally (hazard ratio: 1.13, 95% confidence interval [CI]: 0.95-1.33) or by cesarean delivery (hazard ratio: 1.08, 95% CI: 0.88-1.32). At 5 years of age, among 10 404 children retained in the study, GBS prophylaxis was not associated with the composite outcome in vaginal (odds ratio: 1.21, 95% CI: 0.96-1.52) or cesarean delivery (odds ratio: 1.17, 95% CI: 0.88-1.56) cohorts. Outcomes of asthma, eczema, food allergy, separately, and allergic rhinitis were also not associated with GBS prophylaxis.

CONCLUSIONS

Intrapartum GBS prophylaxis was not associated with subsequent diagnosis of asthma, eczema, food allergy, or allergic rhinitis in the first 5 years of age.

Group B streptococcal disease in the mother and newborn-A review

Group B Streptococcus, a common commensal in the gut of humans and in the lower genital tract in women, remains an important cause of neonatal mortality and morbidity. The incidence of early onset disease has fallen markedly in countries that test women for carriage at 35-37 weeks of pregnancy and then offer intrapartum prophylaxis with penicillin during labour. Countries that do not test, but instead employ a risk factor approach, have not seen a similar fall. There are concerns about the effect on the neonatal microbiome of widespread use of antibiotic prophylaxis during labour, but so far the effects seem minor and temporary. Vaccination against GBS would be acceptable to most women and GBS vaccines are in the early stages of development. Tweetable abstract: Group B Strep is a key cause of infection, death and disability in young babies. Antibiotics given in labour remain the mainstay of prevention, until a vaccine is available.

Development and analytical validation of real-time PCR for the detection of Streptococcus agalactiae in pregnant women

Background

Group B Streptococcus (GBS) is the leading cause of invasive neonatal infection. In this study, we aimed to evaluate the analytical validation of qualitative real-time polymerase chain reaction (qPCR) as a means to detect GBS.

Methods

Genomic DNA (gDNA) was purified from 12 ATCC bacterial strains, two belonging to GBS and the remainder acting as negative controls. Additionally, gDNA was isolated from 21 strains of GBS from various serotypes (Ia, Ib and II-VIII). All gDNA was used to evaluate the analytical validation of the qPCR method employing a specific Taqman probe. Inclusivity, exclusivity, anticipated reportable range, the limit of detection and robustness were evaluated. The methods used are described in international guidelines and other existing reports. The performance of this qPCR method for detecting GBS was compared to other microbiological methods used with vaginal-rectal samples from pregnant women.

Results

Our qPCR method for detecting GBS was analytically validated. It has a limit of detection of 0.7 GE/μL and 100% analytical specificity. It detects all strains of GBS with the same level of performance as microbiological methods.

Conclusion

Data suggest that this qPCR method performs adequately as a means to detect GBS in vaginal-rectal swabs from pregnant women.