RESUMO
We investigated the molecular epidemiology of Streptococcus agalactiae (Group B Streptococcus, GBS) from carriage in a cohort of pregnant mothers and their respective newborns in a Teaching Hospital in Sri Lanka. GBS vaginal carriage was assessed on pregnant mothers at pre-delivery (n = 250), post-delivery (n = 130), and from peri-rectal swabs of neonates (n = 159) in a prospective study. All colonizing, non-duplicate GBS isolates (n = 60) were analyzed for antimicrobial susceptibilities, capsular serotyping, and whole-genome sequencing (WGS). The percentage of GBS carriage in mothers in the pre-delivery and post-delivery cohorts were 11.2% (n = 28) and 19.2% (n = 25), respectively, and 4.4% (n = 7) in neonates. GBS isolates predominantly belonged to serotype VI (17/60, 28.3%). The isolates spanned across 12 sequence types (STs), with ST1 (24/60, 40%) being the most predominant ST. Concomitant resistance to erythromycin, tetracyclines, and gentamicin was observed in eight strains (13.3%). WGS revealed the presence of antimicrobial resistance genes including ermA (5/60), mefA (1/60), msrD (1/60), and tetLMO (2/60, 28/60, and 1/60, respectively) among 60 strains. The study provides insight into the diversity of vaccine targets of GBS since serotype VI is yet to be covered in the vaccine development program.
RESUMO
BACKGROUND: Maternal vaginal colonization with antibiotic resistant organisms is a growing concern in countries with high antibiotic resistance rates. METHODS: A low vaginal swab was collected from mothers on admission, on discharge and a peri-rectal swab was collected from the neonates born to these mothers on discharge. Routine microbiological methods were used to identify the colonization rates for Escherichia coli, Klebsiella spp. and Streptococcus agalactiae. RESULTS: The pre-delivery colonization rate among the 250 participants for total Enterobacteriaceae was 18.8%. The colonization rates for Klebsiella spp., E. coli and S. agalactiae were, 12.4, 5.6 and 14.8% respectively. Two Klebsiella spp. and two E. coli isolates were confirmed to be exentend spectrum ß lactamase (ESBL) producers with the commonest resistant determinant being blaCTX-M. Post-delivery swabs were collected from 130 participants and the colonization rates were 41.5% for Enterobacteriaceae, 25.4% for Klebsiella spp., 10.8% for E. coli, and 10.8% for S. agalacteiae. Three Klebsiella isolates and one E. coli isolate were confirmed to be ESBL producers with the commonest resistant determinant being blaCTX-M. Considering the 130 participants with both samples, there was a significant increase in the colonization with any Enterobacteriaceae and Klebsiella spp. (p < 0.05). Peri-rectal swabs were collected from neonates in 159 instances. The isolation rates for Enterobacteriaceae was 34%. The genus specific isolation rate for Klebsiella was 21.4% while the rates for E. coli and S.agalactiae were 10.1 and 5.7% respectively. Two of the E. coli were confirmed to be ESBL producers while none of the klebsiellae were identified to be so. Considering these 159 instances where both the mother and baby were sampled, random amplification of polymorphic DNA (RAPD) analysis revealed that Enterbacteriaceae with same strain type was present in 6.9% of the instances, indicating possible transfer between the mother and neonate. The transfer rate for ESBL producers were 0.6%. CONCLUSIONS: The lower level of antimicrobial resistance among these potentially community acquired isolates is encouraging. However, in view of the increasing level of resistance reported elsewhere in the region, regular monitoring is warranted.
