Whole Genome Sequence based Capsular Typing and Antimicrobial Resistance Prediction of Group B Streptococcal Isolates from Colonized Pregnant Women in Nigeria

Abstract

\n Background: Streptococcus agalactiae (Group B Streptococcus, GBS) is one of the major bacterial pathogens responsible for neonatal sepsis. Whole genome sequencing has, in recent years, emerged as a reliable tool for capsular typing and antimicrobial resistance prediction. This study characterized vaginal and rectal isolates of Group B Streptococcus obtained from pregnant women in Port Harcourt, Nigeria using a whole-genome sequence-based approach.Results: Capsular types Ia, Ib, II, III, IV and V were detected among the 43 isolates sequenced. Twelve sequence types (STs) were identified, with ST19 (n=9, 27.3%) and ST486 (n=5, 15.2%) the most frequent among non-duplicated isolates. Of the alpha-like proteins (alp) identified, Alp1 was the most prevalent in 11 (33.3%) isolates. Macrolide and lincosamide resistance determinants were present in 15 (45.5%) isolates; ermB was detected in 1 (3%) and ermTR in 7 (21.2%) isolates. The lnu gene, was detected in 6 (18.2%) and mef was identified in 3 (9.1%) isolates. Resistance of GBS to erythromycin and clindamycin was found to be 30.3% and 24.2%, respectively. All isolates were resistant to tetracycline with only the tetM gene identified. Fluoroquinolone-resistance conferring substitutions in gyrA + parC were detected in 9 (27.3%) isolates and chloramphenicol resistance was predicted in 11 (33.3%).Conclusion: The data available from the whole genome sequencing of these isolates offers a small but insightful description of common serotypes and resistance features within colonizing GBS in Nigeria.