Genome analysis of clinical isolate of Campylobacter fetus subspecies fetus MMM01 from India reveals genetic determinants of pathogenesis and adaptation.

Abstract

In this study we report the whole genome sequencing (WGS) based analysis of blood-borne Campylobacter fetus subsp. fetus MMM01 isolated from a diabetic patient to obtain deeper insights in to the virulence and host adaptability. The sequenced genome of C. fetus subsp. fetus MMM01 along with reference genomes retrieved from NCBI was subjected to various in-silico analysis including JSpecies, MLST server, PATRIC server, VFanalyzer, CARD, PHASTER to understand their phylogenetic relation, virulence and antimicrobial resistance profile. The genome had a size of 1,788,790 bp, with a GC content of 33.09%, nearly identical to the reference strain C. fetus subsp. fetus 82-40. The MLST based phylogenetic tree constructed revealed the polyphyletic branching and MMM01 (ST25) was found to be closely related to ST11, both belong to the sap-A serotype which are more common in human infections. VFanalyzer identified 88 protein-coding genes coding for several virulence factors including Campylobacter adhesion to fibronectin, flagellar apparatus, cytolethal distending toxin operons and Campylobacter invasion antigen proteins which enhance the virulence of bacteria along with resistance genes against antibiotics including fluoroquinolone, chloramphenicol, tetracycline, and aminoglycoside in MMM01, which points to enhanced survival and pathogenicity of this zoonotic pathogen. It was interesting to find that MMM01 lacked FGI-II island found in most of the clinical isolates, which encoded CRISPR Cas and prophage II regions. More details about the complexity and evolution of this zoonotic pathogen could be learned from future studies that concentrate on comparative genome analysis using larger genome datasets.