Is Group B Streptococcus Colonization Associated with Maternal Peripartum Infection in an Era of Routine Prophylaxis?

Association between Group B Streptococcus and Clinical Chorioamnionitis by Gestational Week at Delivery-A Multicenter Cohort Study

OBJECTIVE

 In the era of group B Streptococcus (GBS) screening and intrapartum antibiotic prophylaxis (IAP), GBS colonization has been associated with a lower risk of chorioamnionitis, possibly due to a protective effect of IAP. We sought to confirm this finding and assess whether this association varies by gestational week at delivery.

STUDY DESIGN

 We performed a retrospective cohort study of term (37.0-42.6 weeks), singleton parturients with known GBS status who delivered from 2005 to 2021 at two academic medical centers in Israel. We excluded patients who underwent planned cesarean, out of hospital birth, or had a fetal demise. Patients received GBS screening and IAP for GBS positivity as routine clinical care. The primary outcome was a diagnosis of clinical chorioamnionitis as determined by the International Classification of Diseases 10th Revision code, compared between GBS-positive and -negative groups, and assessed by gestational week at delivery.

RESULTS

 Of 292,126 deliveries, 155,255 met inclusion criteria. In total, 30.1% were GBS positive and 69.9% were negative. GBS-positive patients were 21% less likely to be diagnosed with clinical chorioamnionitis than GBS-negative patients, even after controlling for confounders (1.5 vs. 2.2%, adjusted odds ratio: 0.79, 95% confidence interval: 0.68-0.92). When assessed by gestational week at delivery, there was a significantly greater difference in rates of clinical chorioamnionitis between GBS-positive versus GBS-negative groups with advancing gestational age: 1.5-fold difference at 38 to 40 weeks, but a twofold difference at 42 weeks. The risk of clinical chorioamnionitis remained stable in the GBS-positive group, but increased significantly in the GBS-negative group at 41- and 42-week gestation (2.0 vs. 2.9%, p < 0.01 at 41 weeks; up to 3.9% at 42 weeks, p < 0.01).

CONCLUSION

 In a large multicenter cohort with universal GBS screening and IAP, GBS positivity was associated with a lower risk of chorioamnionitis, driven by an increasing rate of chorioamnionitis among GBS-negative patients after 40 weeks.

KEY POINTS

· GBS positivity and IAP may be associated with lower risk of chorioamnionitis.. · GBS-positive patients were less likely to be diagnosed with chorioamnionitis.. · This difference increased with advancing gestational age after 40 weeks..

Association between intrapartum antibiotic prophylaxis for Group B Streptococcus colonization and clinical chorioamnionitis among patients undergoing induction of labor at term

BACKGROUND

Rectovaginal colonization with Group B Streptococcus during pregnancy has historically been shown to be associated with an increased risk of clinical chorioamnionitis and peripartum infectious morbidity.

OBJECTIVE

Newer observational data in the era of intrapartum antibiotic prophylaxis suggest a possible reversal of this association; however, it is unclear if this is related to differences in labor management for those with and without Group B Streptococcus colonization. We therefore sought to assess the association between intrapartum antibiotic prophylaxis for Group B Streptococcus colonization and clinical chorioamnionitis within the context of a randomized induction of labor trial with a standardized labor protocol.

STUDY DESIGN

We performed an exploratory secondary analysis of a randomized trial of patients undergoing term induction at a tertiary care center. Patients received third trimester Group B Streptococcus screening and intrapartum antibiotic prophylaxis as routine care. Group B Streptococcus detection was performed using a carrot broth-enhanced subculture to Group B Streptococcus Detect approach (Hardy Diagnostics, Santa Maria, CA). Labor management was protocolized per the trial. Patients with unknown Group B Streptococcus status or who did not receive intrapartum antibiotic prophylaxis, if indicated, were excluded. The primary outcome was diagnosis of clinical chorioamnionitis, compared between patients who received intrapartum antibiotic prophylaxis for known Group B Streptococcus positive status (by culture, history, or Group B Streptococcus bacteriuria) and those who were Group B Streptococcus negative and did not receive intrapartum antibiotic prophylaxis. Secondary outcomes included postpartum endometritis, wound infection, a composite maternal peripartum infectious morbidity, and neonatal outcomes.

RESULTS

A total of 491 patients were enrolled in the trial. Of these, 466 had a known Group B Streptococcus status and received or did not receive intrapartum antibiotic prophylaxis accordingly and were included in this analysis: 292 (62.7%) were Group B Streptococcus negative and did not receive intrapartum antibiotic prophylaxis, and 174 (37.3%) were Group B Streptococcus positive and received intrapartum antibiotic prophylaxis. The majority of patients were Non-Hispanic Black (78.1%) and nulliparous (59.7%). There were no differences in demographic, clinical, induction or labor characteristics between groups. Patients who were Group B Streptococcus positive had a 49% lower rate of clinical chorioamnionitis (8.1% vs 14.7%, odds ratio, 0.51; P=.03) and a lower rate of peripartum infectious morbidity (8.1% vs 15.8%, odds ratio, 0.47; P=.02) compared to those who were Group B Streptococcus negative. Infants born to patients who were Group B Streptococcus positive were significantly less likely to be admitted to the neonatal intensive care unit (3.4% vs 15.1%, P<.001).

CONCLUSION

Although Group B Streptococcus colonization has historically been considered a risk factor for clinical chorioamnionitis, in the era of universal antibiotic prophylaxis for Group B Streptococcus positive patients, our findings support the point that intrapartum antibiotic prophylaxis for Group B Streptococcus positivity is associated with lower rates of clinical chorioamnionitis and peripartum infectious morbidity among patients undergoing induction with protocolized labor management. These findings demonstrate that intrapartum antibiotic prophylaxis for Group B Streptococcus may protect against perinatal infectious morbidity, a phenomenon that warrants further investigation.

Group B Streptococcus and Pregnancy: Critical Concepts and Management Nuances

Importance

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

Objective

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

Evidence Acquisition

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

Results

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

Conclusions

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

Causes of early postpartum complications that result in visits to the emergency department

OBJECTIVE

This study aimed to review the reasons why postpartum women present to the emergency department (ED) over a short term (≤10 days post-delivery) and to identify the risk factors associated with early visits to the ED.

METHODS

This retrospective chart review included all women who delivered at a regional health system (William Osler Health System, WOHS) in 2018 and presented to the WOHS ED within 10 days after delivery. Baseline descriptive statistics were used to examine the patient demographics and identify the timing of the postpartum visit. Univariate tests were used to identify significant predictors for admission. A multivariate model was developed based on backward selection from these significant factors to identify admission predictors.

RESULTS

There were 381 visits identified, and the average age of the patients was 31.22 years (SD: 4.83), with median gravidity of 2 (IQR: 1-3). Most patients delivered via spontaneous vaginal delivery (53.0%). The median time of presentation to the ED was 5.0 days, with the following most common reasons: abdominal pain (21.5%), wound-related issues (12.6%), and urinary issues (9.7%). Delivery during the weekend (OR 1.91, 95% CI 1.00-3.65, P = 0.05) was predictive of admission while Group B Streptococcus positive patients were less likely to be admitted (OR 0.22, CI 0.05-0.97, P<0.05).

CONCLUSIONS

This was the first study in a busy community setting that examined ED visits over a short postpartum period. Patient education on pain management and wound care can reduce the rate of early postpartum ED visits.

Biomarkers for a histological chorioamnionitis diagnosis in pregnant women with or without group B streptococcus infection: a case-control study

Background

Chorioamnionitis may cause serious perinatal and neonatal adverse outcomes, and group B streptococcus (GBS) is one of the most common bacteria isolated from human chorioamnionitis. The present study analyzed the impact of GBS infection and histological chorioamnionitis (HCA) on pregnancy outcomes and the diagnostic value of various biomarkers.

Methods

Pregnant women were grouped according to GBS infection and HCA detection. Perinatal and neonatal adverse outcomes were recorded with a follow-up period of 6 weeks. The white blood cell count (WBC), neutrophil ratio, and C-reactive protein (CRP) level from peripheral blood and soluble intercellular adhesion molecule-1 (sICAM-1), interleukin 8 (IL-8), and tumor necrosis factor α (TNF-α) levels from cord blood were assessed.

Results

A total of 371 pregnant women were included. Pregnant women with GBS infection or HCA had a higher risk of pathological jaundice and premature rupture of membranes and higher levels of sICAM-1, IL-8, and TNF-α in umbilical cord blood. Univariate and multivariate regression analysis revealed that sICMA-1, IL-8, TNF-α, WBC, and CRP were significantly related to an increased HCA risk. For all included pregnant women, TNF-α had the largest receiver operating characteristic (ROC) area (area: 0.841; 95% CI: 0.778–0.904) of the biomarkers analyzed. TNF-α still had the largest area under the ROC curve (area: 0.898; 95% CI: 0.814–0.982) for non-GBS-infected pregnant women, who also exhibited a higher neutrophil ratio (area: 0.815; 95% CI: 0.645–0.985) and WBC (area: 0.849; 95% CI: 0.72–0.978), but all biomarkers had lower value in the diagnosis of HCA in GBS-infected pregnant women.

Conclusion

GBS infection and HCA correlated with several perinatal and neonatal adverse outcomes. TNF-α in cord blood and WBCs in peripheral blood had diagnostic value for HCA in non-GBS-infected pregnant women but not GBS-infected pregnant women.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03731-7.