Routine tests and automated urinalysis in patients with suspected urinary tract infection at the ED

Urinary tract infections (UTIs) are frequently encountered. Diagnostics of UTI (urine dipstick, Gram stain, urine culture) lack proven accuracy and precision in the emergency department. Utility of automated urinalysis shows promise for UTI diagnosis but has not been validated.

A total of 381 cases presenting with fever and/or clinically suspected UTI were analyzed. Diagnosis was based on clinical presentation, urine culture and/ or blood culture, and successful treatment. Performance of standard diagnostics and automated urinalysis (Sysmex UF-1000i) was analyzed at various cutoff values, and diagnostic algorithms were tested.

One hundred forty-three (37.5%) cases were diagnosed with UTI. Sensitivity of urine dipstick nitrite was 32.9% and specificity was 93.7%. Sensitivity of urine dipstick leukocyte esterase (3+) was 80.4% and specificity was 82.8%. Receiver operating characteristic curves of automated bacterial and leukocyte count showed area under the curve of 0.851 and 0.872, respectively. Cutoff values of 133 bacteria/μL and 48 leukocytes/μL resulted in >90% sensitivity. Diagnostic values for complicated cases (antibiotics, catheters) were inferior to uncomplicated cases. Algorithms combining dipstick and automated counts did not improve accuracy with the exception of a 5.2% increase in uncomplicated cases (n=247).

Automated leukocyte and bacterial count can be used in the emergency department setting with comparable accuracy compared with standard dipstick analysis with minor improvement when combined.