Serotype distribution and antimicrobial susceptibility profile of invasive group B streptococcal disease-in South Indian population.

Invasive group B Streptococcal disease (iGBS) is an important cause of morbidity and mortality in neonates for which the development of an efficacious vaccine remains a global health imperative. The knowledge about the serotype distribution of iGBS is important component for formulation of Capsular polysaccharide (CPS)-based vaccine. However, there were absolute lack of information on serotype distribution in invasive GBS isolates from Indian subcontinent. Methods This study has assessed the serotype distribution and antimicrobial susceptibility profile of invasive group B streptococcal isolates for a period of 13 years from 2009 to 2022 from a tertiary care Center in South India. A total of 155 iGBS isolates were subjected to serotyping by conventional multiplex PCR for identification of all ten GBS serotype. Antimicrobial susceptibility profile and demographic details were extracted from microbiological records. Results Overall, the most common serotype causing invasive GBS were Ia (29%), V (26%), III (15%), II (12%), VI (6%), VII (5%) and Ib (5%). Serotypes IV, VIII and XI were not detected. Among the early-onset iGBS, the common serotype were Ia (36%), V (27%), and III (8%). In late onset iGBS, Serotype III (44%) was predominant. The common serotype in adults were Serotype V (31%) and III (20%). All the invasive GBS isolates were susceptible for penicillin (100%), but the susceptibility for clindamycin and erythromycin were 72% and 80% respectively. Conclusion The serotype distribution of invasive Group B streptococcal isolates from India suggest that hexavalent group B CPS vaccine will cover only 90% of GBS isolates causing invasive disease among the infants in India. Continued surveillance monitoring for serotype distribution and antimicrobial resistance patterns for iGBS are warranted to make public health interventions.