Rapid filter-based detection and culture of burkholderia pseudomallei from small volumes of urine

Abstract

Clinical outcomes of melioidosis patients improve when the infecting agent, Burkholderia pseudomallei, is rapidly detected and identified by laboratory testing. Detection of B. pseudomallei DNA or recovery of the pathogen by culture from urine can support a diagnosis of melioidosis and guide patient care. Two new methods, designated filter-capture DNA isolation (FCDI) and filter cellular recovery (FCR), were developed to increase the sensitivity of detection and recovery of viable B. pseudomallei cells from small volumes (0.45 ml) of urine. DNA from eight strains of B. pseudomallei that were spiked into synthetic urine at low concentrations (1 × 102 CFU/ml) was detected in FCDI cell lysates using real-time PCR with greater consistency than with preparations from a QIAamp DNA Blood minikit. The FCR method showed greater B. pseudomallei detection sensitivity than conventional urine culture methods and resulted in typical colony growth at 24 h from as few as 1 × 102 CFU/ml. In addition, the FCR method does not rely on precipitation of a urine pellet by centrifugation and requires a smaller volume of urine. The FCDI and FCR methods described here could improve time-to-results and decrease the number of negative B. pseudomallei reports that are currently observed from urine culture as a consequence of samples containing low or variable bacterial cell concentrations.