Antibiotics lower PSA in patients with prostatitis

San Francisco-Elevated PSA levels in men who have chronic bacterial prostatitis return to normal after antimicrobial treatment with either levofloxacin (Levaquin) or ciprofloxacin (Cipro), according to researchers from Northwestern University and Ortho-McNeil Pharmaceutical.

In a study that underscores an apparent, direct correlation between clinical infection and increased PSA in some men, a multicenter, double-blind trial demonstrated that the two antimicrobial regimens were able to reduce PSA levels in a large number of infected patients. In fact, the trend holds true for men who did not initially show substantially elevated PSA levels.

"Patients who had contracted bacterial prostatitis and who were treated often had a drop in PSA," said co-author Neringa Zadeikis, MD, director of infectious disease at Ortho-McNeil Pharmaceutical in Raritan, NJ.

However, Anthony J. Schaeffer MD, the study's lead author, said that such an application is not the point, although it may be reasonable to investigate. Trying to delay or eschew biopsy by treating a sharp rise in PSA in such a presumptive way, at the very most, should be transient, he said.

"It should be a very short course of therapy," said Dr. Schaeffer, professor and chairman of the department of urology at Northwestern University, Chicago.

Although past investigations suggest that men with chronic bacterial prostatitis who have elevated PSA levels show a reduction in PSA following treatment of their infection, the current study prospectively documented baseline levels, then compared them to post-therapy PSA values.

Two quinolones studied

The analysis included 377 men: 197 received levofloxacin, 500 mg daily, and 180 received ciprofloxacin, 500 mg twice daily, for 28 days. Of these, 35 men in the levofloxacin group and 37 in the ciprofloxacin group had baseline PSA levels >4.0 ng/mL. The baseline mean PSA value was 7.88 ng/mL in the levofloxacin group and 8.76 ng/mL in the ciprofloxacin group. All patients had been found to have chronic bacterial prostatitis.

Dr. Zadeikis reported that 29 levofloxacin patients and 31 ciprofloxacin patients were available for follow-up and had a post-therapy PSA level below 4.0 ng/mL. The mean level of PSA dropped by 2.81 ng/mL among those in the levofloxacin group. Among those in the ciprofloxacin group, the mean level dropped by 3.13 ng/mL. More than 90% showed eradication of the bacterial cause of prostatitis, Dr. Zadeikis said at the AUA annual meeting.

High eradication rates

For patients in the levofloxacin group who had their post-therapy levels of PSA fall below 4.0 ng/mL, nearly 92% had microbiologic eradication, and almost 86% had clinical success. Similarly, 93% of ciprofloxacin patients who had their post-therapy levels of PSA fall below 4.0 ng/mL experienced microbiologic eradication, and 94% were deemed a clinical success, Dr. Zadeikis said.

But in patients for whom the post-therapy PSA level failed to drop to below 4.0 ng/mL, the outcome changed. The microbiologic eradication rate was about 65%, and the clinical response rate was about 74% for the levofloxacin group. The eradication rate and clinical response rate were similar in the ciprofloxacin group-63% and 75%, respectively.

What is the underlying mechanism that would lead to a decrease in PSA levels with bacterial eradication? It remains to be fully described, Dr. Zadeikis said.

"But it seems to be a trend," she said.