IDENTIFICATION OF SPECIFIC ANTIGENS OF PSEUDOMONAS-PSEUDOMALLEI AND EVALUATION OF THEIR EFFICACIES FOR DIAGNOSIS OF MELIOIDOSIS

Current methods for the diagnosis of melioidosis are based on bacterio logical culture. A number of serological tests currently available lac k specificity and sensitivity. This is largely due to the use of crude antigens which results in a significant cross-reactivity with sera fr om individuals infected with other bacteria. In this study five differ ent antigens were prepared and evaluated for their potential usefulnes s in diagnosis of melioidosis. These included a 19.5-kDa antigen which was previously shown to be specific by Western blotting (immunoblotti ng), a crude cell extract, a veronal extract, a 39.0-kDa antigen, and an immunoaffinity-purified antigen. AH antigens were used for detectin g antibody in sera from patients with septicemic melioidosis by indire ct enzyme-linked immunosorbent assay. The results were compared with t hose obtained with sera from patients with other bacterial infections and normal sera from areas where the infection is and is not endemic. The 19.5-kDa antigen exhibited the most satisfactory results, with 92% sensitivity, 91% specificity, 81% positive predictive value, and 96% negative predictive value based on a background obtained with normal s era from the area where the infection is nonendemic. These values were 82% sensitivity, 96% specificity, 94% positive predictive value, and 87% negative predictive value based on results with normal sera from t he area where the infection is endemic. Results from this study showed that the 19.5-kDa antigen was potentially useful in the diagnosis of melioidosis and deserves further investigation.