Abstract
Objectives To isolate Burkholderia pseudomallei from clinical specimens and study the association of virulence genes with clinical
manifestations and outcome in patients with melioidosis.
Materials and Methods Burkholderia
pseudomallei isolates obtained from melioidosis cases diagnosed during 2018 to 2021 were identified
using VITEK 2 system and confirmed by polymerase chain reaction (PCR) targeting a
Type III secretion system gene cluster. Multiplex PCR was performed to detect the
genotypes of lipopolysaccharide (LPS) namely A, B, and B2, and singleplex PCR was
performed to detect the presence of the Burkholderia intracellular motility gene (BimA) and filamentous hemagglutinin gene (fhaB3).
Statistical Analysis Chi-square/Fisher's exact tests were performed to study the association between various
clinical manifestations and outcome and different virulence genes. The results were
expressed as unadjusted odds ratios with 95% confidence intervals.
Results Sixty-seven isolates were available for characterization. BimABm
and BimABp
were observed among 82 and 18% of the isolates, respectively. Both sepsis and mortality
were significantly associated with BimABm
. Majority of the isolates had fhaB3 (97%). Most of the isolates showed the presence of LPS A gene (65.7%) followed by
LPS B gene (6%), while LPS B2 was not detected. Nineteen isolates could not be assigned
to any LPS genotypes.
Conclusion Among the virulence genes studied, only BimABm
was significantly associated with sepsis and mortality. More than a quarter (28.3%)
of the isolates could not be assigned to any LPS genotypes, hinting at a greater genetic
diversity in our isolates.
Keywords
Burkholderia pseudomallei
- melioidosis - virulence genes
