Evaluation of Selective Media for Isolation of Burkholderia pseudomallei

Burkholderia pseudomallei is an environmental gram- negative bacillus that causes melioidosis, an emerging infectious disease that is endemic in Northern Australia and Southeast Asia. Some selective media are used to sustain and support the growth of the bacteria in laboratories such as Ashdown agar, Burkholderia pseudomallei selective agar (BPSA) and MacConkey agar. The growth of B. pseudomallei in a selective agar medium containing gentamicin is debated when more than 80% strains in Sarawak are found to be gentamicin sensitive while strains from other parts of the world B. pseudomallei are gentamicin resistant. The aim of this project is to evaluate the most optimum selective media namely Ashdown agar and MacConkey agar which were modified with the addition of colistin as a selective agent in isolating B. pseudomallei from other Burkholderia species and non-Burkholderia spp. in soils. The soils were sterilized and inoculated with bacterial strains before inoculated onto modified Ashdown agar and modified MacConkey agar. The results show that more than 10% were positive B. pseudomallei on modified Ashdown agar for first and second PCR and only less than 5% were positive B. pseudomallei on modified MacConkey agar for first PCR where second PCR the results for modified MacConkey agar was negative. The combination of Ashdown broth and modified Ashdown agar is better in isolating B. pseudomallei from soils compared to the combination of Ashdown broth and modified MacConkey agar