Usefulness of LAL assay for rapid detection of gram-negative bacteriuria.

LAL assay is a rapid and reliable and easy to perform and interpret urine screen for clinically significant gram-negative bacteriuria. Chromogenic assays are rapid (5 min) and obviate problems associated with gel endpoints, such as inadvertant dissolution of the gel, either during incubation or reading. LAL urine screening is characterized by both high positive and negative predictive values. LAL urine assay identifies gram-negative urinary tract infections by measuring urine endotoxin content as an index for significant numbers of urinary tract pathogens, thus eliminating large numbers of false-positive tests characteristic of other urine screening methods. Screening urine for greater than or equal to 10(5) CFU/ml appears to be an acceptable criterion for defining a UTI in patient populations with low prevalence rates (2-10%). Thus, LAL urine assay may have potential usefulness for screening of asymptomatic populations, such as pregnant women and the elderly.