Use of endotoxin antigens in enzyme-linked immunosorbent assay for the diagnosis of P. pseudomallei infections (melioidosis).

An enzyme-linked immunosorbent assay (ELISA) with endotoxin preparations of P. pseudomallei as antigen was developed for detection of IgG antibodies specific to melioidosis. Forty-seven sera of bacteriologically confirmed melioidosis patients, 55 non-melioidosis sera and 50 sera of healthy blood donors from non-endemic areas were subjected to this assay in comparison with indirect hemagglutination assay (IHA). The data were treated by receiver operating characteristics analysis. The sensitivity, specificity and accuracy in this ELISA were 95.7%, 94.2%, and 94.7%, respectively, with cut-off value of OD = 0.312 at 490 nm. Meanwhile, those in IHA were 81.0%, 91.4%, and 88.1%, respectively, with a cut-off value of > or = 1:160. From these results, the ELISA was judged to be more reliable than IHA as the seroassay for diagnosis of melioidosis.