Inflammation of the prostate caused by a long-standing bacterial infection that often develops insidiously; causative organisms include gram-negative bacteria and enterococci. Clinically, the patient may have mild to moderate low back pain, pain with urination, and perineal discomfort, or he may be asymptomatic. Patients may have a history of multiple urinary tract infections; bacteria can hide in the prostate, which resists penetration by antibiotics, and reinfect the urinary tract. Causal bacteria are identified by culture of prostatic secretions and urine. Treatment consists of ciprofloxacin or another fluoroquinolone antibiotic for 4 to 6 weeks. The long course is needed because of poor penetration into the prostate.