Evaluation of an automated molecular diagnostic instrument for direct detection of Burkholderia pseudomallei from clinical specimens

Abstract

Background. Melioidosis is a potentially life-threatening infectious disease. The diagnosis of melioidosis is time-critical due to the organism's intrinsic antimicrobial resistance and requirement for directed therapy.Aim. To assess the ability of an automated molecular diagnostic instrument to detect Burkholderia pseudomallei directly from clinical samples.Methods. Urine, sputum, swabs and Ashdown's (ASH) broth were spiked with known concentrations of B. pseudomallei and analysed using an automated PCR platform (Panther® Fusion; Hologic) targeting the type III Secretion System (TTS-1) gene. In addition, clinical specimens from patients with confirmed melioidosis were also evaluated.Results. Urine was the clinical sample that demonstrated the lowest limit of detection (LOD), 1.8×102 c.f.u. ml-1. Compared with dry swabs (LOD: 1.0×103 c.f.u. ml-1), Amies agar swabs were inferior (LOD: >3.3×104 c.f.u. ml-1). Inoculation of dry swabs into ASH, with an abbreviated incubation period, did not improve detection. All culture-positive sputum and urine samples from patients with confirmed melioidosis were detected by the PCR method.Conclusion. This study demonstrates the ability of the Panther® to directly detect B. pseudomallei across a range of clinical sample types and estimates the minimum bacterial concentration required for diagnostic detection. The described methodology holds promise for expediting diagnosis and, in turn, enhancing patient outcomes.