Antibiotic screening of urine culture as a useful quality audit

The diagnosis of urinary tract infections includes microbiologic culture of urine to determine the etiology of the infection. However, interpretation of the results can be confounded by various factors including the accuracy of a patient's history of current antibiotic usage.

In this report, we tested urine specimens for the presence of antibiotics and compared our results to the accuracy of antibiotic data entry on the accompanying request forms. In addition, the consequences of culturing urine specimens with incomplete antibiotic history received in the laboratory were investigated.

During the study period, 14,680 urines were obtained and tested with a modified urine antibacterial substance assay (UABA). There were (97.32%) true-negative, 6 (0.04%) false-negative, 222 (1.51%) true-positive and 166 (1.13%) false-positive results. The sensitivity and specificity of this test was 97.37% and 98.85% respectively.

This internal audit practice demonstrates the importance of accurately completed request forms and how this information impacts the clinical interpretation of urine culture results.