Construction of a specific DNA probe for diagnosis of melioidosis and use as an epidemiological marker of Pseudomonas pseudomallei

Abstract

Pseudomonas pseudomallei is a causative agent of melioidosis. The disease manifestations range from fulminant sepsis to asymptomatic seroconversion. In septicemic cases, a mortality rate of 80-90% is reported. Rapid and specific diagnosis has become important to the clinical microbiology laboratory. We have developed a P. pseudomallei-specific DNA probe. The cloned fragment, herein designated pKKU-S23L, contained 1·5 kb of P. pseudomallei chromosomal DNA. A radioactively labelled pKKU-S23L insert could detect 1·5 ng of its genomic DNA or 40 000 P. pseudomallei cells. The probe was highly specific for P. pseudomallei DNA and did not cross-hybridize with DNAs prepared from other related bacteria. Using pKKU-S23L as a probe in total cellular DNA digestions and Southern blot hybridization, we were able to classify 60 P. pseudomallei clinical isolates obtained from individual melioidosis patients into eight categories. Therefore, this probe has a potential not only for use in development of specific detection of bacterial DNA in clinical specimens but also for application in epidemiological studies of P. pseudomallei.