Patient compliance to antibiotic regimens. A simple method of evaluation.

Clinicians are often perplexed by patients with bacterial infection who are not responding to oral antibiotic therapy. Since most of the commonly used antibiotics are excreted in the urine, inhibitory activity of urine against susceptible organisms can be used as a measure of patient compliance. To assess the reliability of this technique, we studied 42 hospitalized patients documented to be receiving oral antibiotics. All urine samples from patients receiving oral antibiotics inhibited bacterial growth at a dilution of greater than or equal to 1:32, while none of the specimens from control patients inhibited growth. Subsequent experience in the outpatient clinic has corroborated the reliability and simplicity of this test as a measure of compliance in patients who are receiving antibiotics either for prophylaxis or for therapy of acute infection.