Long-term antibiotic treatment of chronic bacterial prostatitis. Effect on bacterial flora.

The bacterial flora in patients referred with chronic bacterial prostatitis were studied. Only 13% had Gram-negative bacteria in significant numbers but 43% had Gram-positives using the same criteria. Half of the patients were symptom-free by the end of a 12-week course of antibiotics and remained so after 6 months; in one-third the symptoms were unchanged 6 months after completing treatment. The relief of symptoms correlated with the disappearance of white blood cells in the expressed prostatic secretion (EPS) and with a lowered pH in the EPS. Thus only 1 of the 14 patients without symptoms at 6 months had a significant growth of bacteria at the prostatic level, whereas 7 of 10 patients with unchanged symptoms had a significant bacterial colonisation. Although the initially infecting organism was eliminated in about half of the patients, new Gram-positive bacteria were isolated after treatment in 13 of 29 patients; 12 of these resolved spontaneously within 6 months. Five patients with Gram-positive bacteria were colonised with new Gram-negatives at the end of treatment. Two healed spontaneously but 3 remained colonised with Gram-negatives at the end of the follow-up period. These findings make it likely that many patients infected with Gram-positive bacteria benefit from antibiotic treatment. However, disturbances in the bacterial flora by antibiotic treatment may facilitate invasion by new types of bacteria.