Multilocus sequence types of clinical Burkholderia pseudomallei isolates from peninsular Malaysia and their associations with disease outcomes

Abstract

BackgroundPrevious studies on the Burkholderia pseudomallei genetic diversity among clinical isolates from melioidosis-endemic areas have identified genetic factors contributing to differential virulence. Although it has been ruled out in Australian and Thai B. pseudomallei populations, it remains unclear whether B. pseudomallei sequence types (STs) correlate with disease in Malaysian patients with melioidosis.MethodsIn this study, multi-locus sequence typing (MLST) was performed on clinical B. pseudomallei isolates collected from Kelantan state of Malaysia, patients’ clinical data were reviewed and then genotype-risk correlations were investigated.ResultsGenotyping of 83 B. pseudomallei isolates revealed 32 different STs, of which 13(40%) were novel. The frequencies of the STs among the 83 isolates ranged from 1 to 12 observations, and ST54, ST371 and ST289 were predominant. All non-novel STs reported in this study have also been identified in other Asian countries. Based on the MLST data analysis, the phylogenetic tree showed clustering of the STs with each other, as well as with the STs from Southeast Asia and China. No evidence for associations between any of B. pseudomallei STs and clinical melioidosis presentation was detected. In addition, the bacterial genotype clusters in relation with each clinical outcome were statistically insignificant, and no risk estimate was reported. This study has expanded the data for B. pseudomallei on MLST database map and provided insights into the molecular epidemiology of melioidosis in Peninsular Malaysia.ConclusionThis study concurs with previous reports concluding that infecting strain type plays no role in determining disease presentation.

Molecular analysis of clinical Burkholderia pseudomallei isolates from southwestern coastal region of India, using multi-locus sequence typing

“…ST1368 was found to be the predominant ST representing about 17% of the total isolates. Predominance of particular genotype among single population communities have previously been reported from various endemic areas of Malaysia [ 21 ], Sri Lanka [ 22 ], Thailand, and Australia ( http://pubmlst.org/bpseudomallei/ ).Occurrence of ST1368 over a period of time, which appeared from an isolate of 2006 [ 11 ] and in all 4 states of India suggests high level of genetic uniformity among B . pseudomallei isolates from southwestern region of India.The results of this study suggest that the Indian isolates are closely related with lesser heterogeneity among them and belong to single group.…”

Human Melioidosis

“…However, it should be noted that these studies were performed prior to a published international consensus method for environmental sampling and recovery of B. pseudomallei (100). A notable difference in Singapore isolates is a lack of genetic diversity, with only 3 STs from 13 environmental samples, compared with 9 STs from a single sampling point in Thailand, 33 from Cambodia, 32 from Malaysia, and 13 from Laos (101)(102)(103)(104)(105).…”

Melioidosis in Malaysia: Incidence, Clinical Challenges, and Advances in Understanding Pathogenesis

“…Thus far, this intriguing phenomenon has not been observed in other parts of Malaysia. A recent study by Zueter et al [ 64 ] on genotyping of 83 clinical B. pseudomallei isolates from Peninsular Malaysia revealed 32 different sequence types (STs), of which 13 were novel. All non-novel STs were previously identified in other Asian countries [ 65 , 66 ], suggesting that Malaysian isolates may not be distinct from those of Southeast Asian countries.…”