Efficacy of an enzyme-linked immunosorbent assay for detection of urinary tract immunoglobulins for diagnosis of urinary tract infections

Abstract

Results of the Uristat test (Shield Diagnostics Ltd.), a novel enzyme-linked immunosorbent assay (ELISA) for detection of urine antibodies to seven common bacterial pathogens, were compared with results of urine culture, urinalysis, and clinical history to determine the usefulness of Uristat in the diagnosis of urinary tract infections (UTIs). Midstream, catheterized, and indwelling catheter urine specimens sent to the laboratory for culture were included in the study. Quantitative cultures were performed on both 5% sheep blood agar and eosin-methylene blue agar. Uristat ELISAs were performed according to the manufacturer's instructions. By using a Bacillus subtilis bioassay technique, antibacterial activity was detected in the urine of 236 (22.2%) of 1,061 patients. Probable, possible, or asymptomatic UTIs were diagnosed for 258 (24.3%) of the 1,061 patients. Of those infections, 219 (84.9%) were caused by bacterial species whose antibodies were detectable by Uristat. Uristat's sensitivity and specificity were 76.7 and 56.0%, respectively. Uristat's predictive values of positive and negative results were 31.2 and 90.2%, respectively. Further development of the Uristat test is necessary before it can be of assistance in the diagnosis of UTIs.