Improved diagnosis of melioidosis using a 2-dimensional immunoarray

Melioidosis is caused by the Gram negative bacterium Burkholderia pseudomallei. The gold standard for diagnosis is culture, which requires at least 3-4 days obtaining a result, hindering successful treatment of acute disease. The existing indirect haemagglutination assay (IHA) has several disadvantages, in that approximately half of patients later confirmed culture positive are not diagnosed at presentation and a subset of patients are persistently seronegative. We have developed 2 serological assays, an enzyme-linked immunosorbent assay (ELISA), and a 2-dimensional immunoarray (2DIA), capable of detecting antibodies in patient sera from a greater proportion of IHA-negative patient subsets. The 2DIA format can distinguish between different LPS serotypes. Currently, the 2DIA has a sensitivity and specificity of 100% and 87.1%, respectively, with 100% of culture-positive, IHA-negative samples detected. The ELISA has a sensitivity and specificity of 86.2% and 93.5%, respectively, detecting 67% of culture-positive, IHA-negative samples. The ELISA and 2DIA tests described here are more rapid and reliable for serological testing compared to the existing IHA.