Screening of bacteria in urine using luciferin-luciferase assay of microbial ATP: a comparative study

A total of 3227 urine specimens were analysed to investigate the applicability of a firefly luciferase assay of microbial adenosine triphosphate (ATP) for the rapid screening of bacteriuria in clinical specimens. Urine sediment, dipslide culture, and three plate cultures were also investigated in the majority of the urine specimens, the plate cultures serving as the reference. Of the specimens with positive plate culture (greater than or equal to 10(5) colony forming units (CFU)), leucocyte content of the spun urine sediment was negative (less than or equal to 4 cells per high-power field) in 34% and bacterial content was negative in 14% (no bacteria seen microscopically); the dipslide test was negative (less than 10(5) CFU) in 16%, and the luminescence assay of ATP in 7% (less than or equal to 500 relative light units). Of the urine specimens forming less than 10(5) CFU on plate cultures, leucocytes were positive in 15%, spun sediment bacteria in 21%, the dipslide test in 0.5%, and the luminescence assay of ATP in 11%. When used as a screening test for further studies by complete culture techniques, the luminescence assay of microbial ATP can improve the rapid diagnosis of urinary tract infections.