The association between Maternal GroupB Streptococcus colonization and offspring Gastro-Intestinal morbidity

Objective
Maternal Group B Streptococcus (GBS) colonization is associated with peripartum complications. We sought to evaluate the association between maternal GBS colonization and long-term gastrointestinal (GI) morbidity in the offspring.

Study Design
A population based retrospective cohort study was conducted in a tertiary medical center, serving a population of one million inhabitants. The risk for pediatric GI morbidity of offspring (up to the age of 18 years) was compared among two study groups: exposed and unexposed to maternal rectovaginal GBS colonized mothers, based on perinatal hospitalization databases. All singleton vaginal deliveries occurring between the years 1991-2014 were included. Offspring with congenital malformations were excluded. GI morbidities were based on a pre defined set of ICD-9 codes, as recorded in the hospital computerized files. Kaplan Meier survival curves were used to compare the cumulative risks among the two study groups, and Cox multivariable survival models were used to adjusted for confounding variables.

Results
During the study period, 195,457 newborns met the inclusion criteria; 4820 parturient had a proven diagnosis of GBS colonization. Selected categories of GI morbidity are presented in the Table. Total GI morbidity rate was higher in the GBS positive group as compared with the comparison group (7.69 vs. 5.03/ 1000-person years; Table). Offspring of GBS positive mothers had significantly higher rates of gastroduodenal diseases (0.69 vs. 0.51/1000-person years, p=0.005; Table) and of inflammatory bowel diseases (IBD), 3.03 vs. 1.26/1000 person years, p=0.023). The Kaplan-Meier survival curve demonstrated GBS positive offspring to have a significantly higher cumulative incidence of total GI morbidity (log rank, p=0.002; Figure). The association between maternal GBS and offspring GI morbidity remained significant in the Cox model, which adjusted for maternal age, diabetes, hypertensive disorders and gestational age (adjusted HR=1.2; 95% CI 1.1- 1.2).

Conclusion
Maternal GBS colonization is an independent risk factor for long-term GI morbidity in the offspring, and specifically for gastroduodenal diseases and IBD. The exact mechanism leading to these findings, whether fetal microbiome changes or immunological alterations due to peripartum antibiotic exposure, awaits further investigations.