Detection of gram-negative bacteria in urine by the chromogenic limulus assay

The value of the chromogenic limulus assay for detection of gram-negative bacteria in urine was determined. The assay was performed in microtiter plates at room temperature. In 311 consecutively collected urine samples from patients with suspected urinary tract infection, the assay was positive in all 35 samples containing ⩾ 105 bacteria/ml. No false positive or false negative results were obtained. Four of six urine specimens from patients with gonococcal infection were positive in the assay, whereas samples from patients with chlamydial infection did not yield a positive result. The assay is a rapid and reliable method for detection of urinary tract infection caused by gram-negative bacteria when ⩾ 105 bacteria/ml are present.