The impact of biofilm-producing bacteria on chronic bacterial prostatitis treatment: results from a longitudinal cohort study

We aim to evaluate the role of biofilm-producing bacteria in the clinical response to antibiotic therapy among patients affected by chronic bacterial prostatitis (CBP).

All patients attending our centre from January to December 2008 due to prostatitis-like symptoms with a positive Meares-Stamey test were enroled. The clinical symptoms were assessed according to the NIH-CPSI, and the bacterial strains isolated from the patients enroled were identified and tested for antibiotic sensitivity using cards of the Vitek II semi-automated System for Microbiology (BioMerieux). Quantitative bacterial slime production was assessed by the Christensen microwell assay. All patients were treated with fluoroquinolones for 4 weeks and reevaluated clinically and microbiologically after 3 months.

One hundred and sixteen patients were enroled, and 150 bacterial strains were isolated from all patients. About 85 % of these strains were strong or moderate biofilm producers. Patients with strong or moderate biofilm-producing bacteria had a higher NIH-CPSI symptom score than those without biofilm-producing bacteria (mean 17.6 ± 5.6 vs. 14.1 ± 3.3; p = 0.0009). At the follow-up, 68 patients (58.6 %) had negative microbiological tests, but only 11 (9.48 %) reported a reduction in NIH-CPSI score. Improvement of symptoms was found statistically significantly less frequent in patients with biofilm-producing bacteria than in those without (p = 0.03). Ultrastructural analysis showed cellular forms in active replication with aberrant morphology of unknown cause and confirmed strong slime production with consistent bacterial stratification.

In our CBP population, biofilm-producing bacteria were commonly found and had a significant negative impact on the clinical response to antibiotic therapy.