A 14-year-old previously healthy boy came to the hospital emergency unit with the complaint that he had been kicked in the perineum one week earlier. Immediately after the injury he had developed gross hematuria that resolved in two to three days. Subsequently, he developed severe dysuria, urgency, and frequency. His urine was foul-smelling. He had no fever, flank or suprapubic discomfort. There was no prior history of urinary tract symptoms or of urinary tract operations. He denied exposure to tuberculosis and schistosomiasis, although he had traveled to Greece, in which schistosomiasis is endemic, on three occasions.
He was a moderately obese, postpubertal boy with no other abnormalities on physical examination. A urine culture yielded 100,000 colonies per high-power field of Staphylococcus aureus (coagulase-positive). His serum creatinine level was 0.9 mg/dL. The reaction of an intermediate strength of purified protein derivative was postive but was not of recent conversion. Microscopic