A DECADE OF STUDY ON K. PNEUMONIAE CAPSULAR TYPE DISTRIBUTION IN INDIA – REVEALS HIGH DIVERSITY AND ITS IMPLICATION IN VACCINE DEVELOPMENT

Abstract

Intro: K.pneumoniae is an urgent health concern due to the emergence of multidrug-resistant strains for which vaccination offers potential remedy. Vaccines based on surface polysaccharides are highly promising but need to address high diversity of surface-exposed polysaccharides. For the success of K/O-antigenbased vaccine strategies, knowledge of serotype distribution and diversity among clinical isolates are mandatory. The study aimed to elucidate the genetic diveristy of K.pneumoniae capsular types in India. Methods: 1072 K.pneumoniae isolates collected during 2013-2022 from 38 hospitals were sequenced. The assembled data was uploaded to pathogen watch for analysis, using kleborate for typing K.pneumoniae Findings: The study defines the genetic diversity of O-and K-loci bearing isolates in India. 71 different K-loci were identified in the study. KL64 (25.5%), KL51 (23.2%) and K2 (8.2%) were predominant and 18 isolates had novel cps loci. Prevalence of internationally known KL-types K1 and K2 was 1.3% and 8.2% respectively. 37.2% of KL-64 strains and 85.1% of KL-51 strains belong to clonal lineage ST147 and ST231 respectively. Strikingly, virulence and antibiotic resistance genes were present in high proportion (70.3% virulence, 90.8% resistance) among KL51 strains where as their presence was 31.4% and 90.9% in KL64 strains. Serotypes-O1/O2v1 and-O1/O2v2 were most prevalent accounting for 43.9% and 32.9% respectively. 67% of O1/O2v2 strains harboured KL51 loci and were associated with ST231 clonal lineage, which is a predominant lineage in India. The distribution of virulence and resistance genes was 22.7% and 79.8% among O1/O2v1 strains where as their presence was 58.6% and 69.6% in O1/O2v2 strains Conclusion: The study reveals the existence of diverse population pool of Kantigens among the Indian circulating strains of K.pneumoniae which is different from other parts of the world. The study isolates in addition, displayed a high diverse STs, virulome and resistome. On the contrary, O-antigens were less diverse. The diversity of circulating population has to be considered while developing vaccines.