Oral fosfomycin may be a viable alternative to fluoroquinolones for treating chronic bacterial prostatitis, according to the findings of a small study presented at the 2015 Interscience Conference on Antimicrobial Agents and Chemotherapy in San Diego.

The study by Ilias Karaiskos, MD, of Hygeia General Hospital in Athens, Greece, and colleagues included 20 patients with a mean age of 53.6 years. Oral fosfomycin was taken once daily at a dosage of 3 grams for the first week, followed by 3 grams every 48 hours for a total of 6 weeks. Of the 20 patients, 17 (85%) experienced clinical cure, meaning all signs of infection (clinical and imaging) had resolved or improved during therapy.

Patients were considered to have chronic prostatitis if they had the following features: voiding symptoms and/or pain; positive Meares-Stamey procedure or a positive urine culture; and a transrectal ultrasound and/or magnetic resonance imaging scan of the prostate indicating signs of inflammation.

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The most common pathogen isolated was Escherichia coli (65% of patients). Of the 20 strains isolated from patients, 15 (75%) were resistant to fluoroquinolones. All strains were sensitive to fosfomycin, the researchers reported.

Fluoroquinolones have been a cornerstone of treatment for chronic bacterial prostatitis. Oral fosfomycin appears to be a successful alternative to this class of agents, particularly with the growing problem of multi-drug resistant (MDR) bacteria, according to the investigators, who noted that more studies are needed to clarify the exact dosage regimen.

J. Curtis Nickel, MD, a professor of urology at Queens University in Kingston, Ontario, Canada, who has studied chronic prostatitis extensively, noted that with the growing prevalence of MDR bacterial infections of the urinary tract—including the prostate—fosfomycin deserves another look. He called fosfomycin “an antibiotic almost forgotten [about] in our enthusiastic response to the introduction of sequential fluoroquinolones.”

“Based on its ability to penetrate bacterial aggregates, we suggested 20 years ago that it might eventually be used for biofilm-related infections such as chronic prostatitis,” said Dr. Nickel, citing a study he and his colleagues published in Antimicrobial Agents and Chemotherapy (1995;39:1038-1044).

Dr. Nickel observed that fosfomycin never became popular because the fluoroquinolones were so effective. “But those days are almost over,” Dr. Nickel told Renal & Urology News. “This study [by Dr. Karaiskos and colleagues] strongly suggests that the theoretical benefits of fosmomycin may indeed turn out to be very clinically important.”

He said he agrees with the study authors that more research is required, but noted that “when confronted with chronic bacterial prostatitis with multi-resistant bacteria, I do not hesitate to use fosfomycin as a viable treatment option.”