Molecular insights of melioidosis causing Burkholderia pseudomallei strains in Sri Lanka

Abstract

Objectives: Objectives: Gram-negative pathogenic bacterium Burkholderia pseudomallei is the causative organism of melioidosis, predominantly reported in Southeast Asia. The infections in humans can be recurrent, and sometimes difficult to cure. Studying the genome of B. pseudomallei is the key to understand origins, transmission routes, and phylogenetic relationships. Methods: We compared all available B. pseudomallei genomes from the NCBI database representing Sri Lanka to 15 previously reported genomes in Asia. The analysis involved in silico MLST, wgMLST, single nucleotide polymorphism (SNP), average nucleotide identity (ANI), clonal complexes (CC), virulence, and antibiotic resistance profiles. Results: The MLST analyses of 24 strains revealed, 6 Sri Lankan and 1 Indian strain formed CC594*, a novel single locus variant clonal complex, and 3 strains from Malaysia, Vietnam, Thailand formed another clonal complex named CC70*. From 9 Sri Lankan strains, BPs122 and BPs133 had ancestral origins tied to BPs114 with 114/99.6% and 140/99.6% for SNPs/ANIs. In CC70*, Thailand and Vietnam strains had 1196/99.95% for SNPs/ANIs, respectively. Among the Sri Lankan strains, actin-based motility gene bimA detected in BPs110 only, whereas LPS antigen was presented in BPs112, BPs115, and BPs116 genomes. A total of 67 genes related to antibiotic resistance (22 multidrug efflux systems, 10 regulators modulating/expression of antibiotic resistance, and 11 antibiotic inactivation enzymes related genes) were identified. Conclusion: The B. pseudomallei strains in Sri Lanka represent a highly diverse nature and some of them had clonal relationships with other Asian strains. The present study concludes B. pseudomallei strains in Sri Lanka have probably risen from different ancestral origins. J Microbiol Infect Dis 2020; 10(4): 215-221.