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

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