If a woman has taken OTC phenazopyridine (Uristat, Azo), and urine dipstick results are skewed, is it appropriate to treat empirically with antibiotics based on history and exam findings? For context, this question applies to a setting in which a microscope is not available. — Sangeetha Larsen, PA-C, Rockford, Minn.

Phenazopyridine is effective in reducing the discomfort that accompanies urinary tract infection (UTI) but does not treat the underlying cause of the inflammation. It should not be used for more than two days. Urine dipstick is often used to diagnose UTI, but the sensitivity of this method can be as low at 60%. It is more useful in ruling out infection than ruling in.

Presence of nitrites and leukocyte-esterase is often taken as diagnostic of infection, but confirmation with microscopy and culture is recommended. Phenazopyridine will often cause false-positive results of urine dipstick testing. If a patient has taken phenazopyridine, culture is warranted for diagnosis. Decision to treat based on history and exam findings may be acceptable but should be reassessed after culture returns. — Claire Babcock O’Connell, MPH, PA-C (151-3)

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