Validation of a Lateral Flow Test for the Presumptive Identification of the Presence of Burkholderia mallei or Burkholderia pseudomallei in Environmental Samples

Abstract

We conducted a comprehensive, multiphase laboratory evaluation of InBios Active Melioidosis Detect (AMD) rapid test, a lateral flow immunoassay designed to detect capsular polysaccharides produced by Burkholderia mallei or Burkholderia pseudomallei, used in conjunction with the Omni Array Reader (OAR) for the rapid detection of B mallei or B pseudomallei in environmental (nonclinical) samples at 2 sites. The limit of detection, using reference strains B mallei strain ATCC 23344 and B pseudomallei strain ATCC 11668, was determined to be 10³ to 10⁴ CFU/mL. In different phases of the evaluation, inclusivity strains that included geographically diverse strains of B mallei (N = 13) and B pseudomallei (N = 22), geographically diverse phylogenetic near neighbor strains (N = 66), environmental background strains (N = 64), white powder samples (N = 26), and environmental filter extracts (N = 1 pooled sample from 10 filter extracts) were also tested. A total of 1,753 tests were performed, which included positive and negative controls. Visual and OAR results showed that the AMD test detected 92.3% of B mallei and 95.5% of B pseudomallei strains. Of the 66 near-neighbor strains tested, cross-reactivity was observed with only B stabilis 2008724195 and B thailandensis 2003015869. Overall, the specificity and sensitivity were 98.8% and 98.7%, respectively. The results of this evaluation support the use of the AMD test as a rapid, qualitative assay for the presumptive detection of B mallei and B pseudomallei in suspicious environmental samples such as white powders and aerosol samples by first responders and laboratory personnel.