Unraveling the implications of environmental, host and pathogen-specific determinants on clinical presentations and disease progression among Indian melioidosis patients.

Background: Melioidosis is gaining recognition as an emerging infectious disease with diverse clinical manifestations and high-case fatality rates,worldwide. However, the molecular epidemiology of the disease outside the endemic regions such as,Thailand and Northern Australia remains unclear. Methods: Clinical data and B. pseudomallei (Bps) isolates obtained from 199 culture-confirmed cases of melioidosis, diagnosed during 2006-2016 inSouth India were used to elucidate the host and pathogen-specific variable virulence determinants associated with clinical presentations and disease progression. Further, we determined the temporal variations and the influence of ecological factors on Bps Lipopolysaccharide (LPS) genotypes causing infections. Result: Severe forms of the disease were observed amongst 169 (85%) patients. Renal dysfunction and infection due to Bps harboring Bim-ABm variant had significant associations with severe forms of the disease. Diabetes mellitus, septicemic melioidosis, and infection due to LPS-B genotype were independent risk factors for mortality. LPS-B (74%) and LPS-A (20.6%) were the prevalent genotypes causing infections. Both genotypes demonstrated temporal variations and had significant correlations with rainfall and humidity. Conclusion: Our study findings suggest that the pathogen-specific virulence traits, under the influence of environmental factors, are the key drivers for geographical variations in the molecular epidemiology of melioidosis.