New findings raise questions about the practice of prescribing antibiotics to men prior to prostate biopsy if they have newly elevated PSA levels and a normal digital rectal examination (DRE).

The thinking behind this practice is that prostatic inflammation is known to raise PSA levels, and studies have shown that antibiotic treatment can lower those levels. In a study of 100 men (mean age 62.9 years) with elevated total PSA (between 4 and 10 ng/mL) and a normal DRE, Turkish investigators demonstrated that although antibiotic treatment decreased total PSA, it did not decrease the risk of a positive prostate biopsy, even if PSA dropped to below 4.

“Therefore, prescribing antibiotics for asymptomatic men with a newly increased PSA may not be an appropriate…management,” the authors concluded in The Journal of Urology (2009;181:128-132).

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The 100 men received 400 mg ofloxacin daily for 20 days and were then re-evaluated. Regardless of the total PSA value after treatment, investigators performed transrectal ultrasound-guided prostate biopsy. Twenty-three men (23%) had histologically proven prostate cancer.

Postantibiotic decreases in total PSA were similar whether patients had prostate cancer or not. In 17 of the 100 patients, total PSA dipped to below 4 following antibiotic treatment. Of these patients, five (29.4%) had prostate cancer on biopsy. No differences in PSA parameters were observed between patients who had cancer and those who did not.