Molecular and Biological Characterisation of Burkholderia pseudomallei

Abstract

The studies presented in this thesis included phenotypic and molecular characterization of B. pseudomallei. A total of 55 clinical isolates were obtained from 44 culture proven melioidosis cases. The highest numbers of patients in this study were from Tamil Nadu (n=14) followed by West Bengal (n=9), Orissa (n=5) and Kerala (n=5). Of the 55 clinical isolates 36 (65%) were from septicaemic individuals. Among the patients 95% were male and median age of patients was 48 years. Diabetes mellitus was the major risk factor (59.5%) seen in this study population followed by alcohol consumption (13%) and renal disease (11%). All the 55 clinical isolates had typical culture and biochemical characteristics described for B. pseudomallei. These isolates were found to be non-arabinose assimilators (Ara+), in concordance with the known pattern for human isolates. This particular biochemical reaction distinguishes B. pseudomallei from that of B. thailandensis; they are morphologically and immunologically close with similar antibiogram. Analysis of the antimicrobial susceptibility pattern of B pseudmallei revealed that all the isolates were susceptible to ceftazidime and imipenem but resistant to gentamicin and ampicillin. Of the isolates 29% were susceptible to ciprofloxacin and 71% were susceptible to cefotaxime and the remaining were intermediately resistant to cefotaxime. FUTURE PERSPECTIVES: The virulence testing for B. pseudomallei could be done in secondary and tertiary level laboratories using the convenient C .elegans model. The co-agglutination test could be easily applied in the secondary level laboratories for confirmation of B. pseudomallei in blood culture. In tertiary laboratories a real -time PCR for the 16S rRNA sequence can be applied for the detection of B. pseudomallei in clinical samples. For molecular epidemiological studies the technique of RAPD and ISSR can be used successfully. A detailed investigation is required to fully study the environmental distribution of this organism in India and identify high risk areas.