Oral fosfomycin for the treatment of chronic bacterial prostatitis

Background: Chronic bacterial prostatitis (CBP) is a difficult-to-treat infection as only a few antibiotics achieve therapeutic concentrations in the prostate. Data on the efficacy and safety of oral fosfomycin for the treatment of CBP are limited. Objectives: To analyse the efficacy and safety of fosfomycin in CBP due to MDR pathogens. Methods: In a prospective observational study, an oral regimen of 3 g of fosfomycin q24h for 1 week followed by 3 g q48h for a treatment duration of 6-12 weeks was administered. The outcome was clinical and microbiological cure rate at the end of treatment (EOT) and rate of relapse at 3 and 6 months. Results: The study included 44 patients. The most common pathogen was Escherichia coli (66%), followed by Klebsiella spp. (14%) and Enterococcus faecalis (14%). Most strains were MDR (59%) and 23% had an ESBL phenotype; 33 of 44 strains were resistant to fluoroquinolones, but all were susceptible to fosfomycin (median MIC for Gram-negative pathogens 1.5 mg/L). In 25 patients, treatment was administered for 6 weeks, whereas in the remaining 19 patients it was prolonged to 12 weeks based on the presence of calcifications in the prostate. Cure rate was 82% at EOT and 80% and 73% at 3 and 6 months accordingly. Microbiological eradication was achieved in 86% and 77% at EOT and at 6 months, respectively. Failure was observed in 12 patients. The most common adverse event was diarrhoea (18%). Conclusions: Oral fosfomycin, particularly in the era of MDR prevalence, represents an attractive, safe and effective alternative to fluoroquinolones for the treatment of CBP.