Value of semen culture in the diagnosis of chronic bacterial prostatitis: a simplified method

Abstract

Objective: To investigate the role of semen cultures versus segmented urine cultures for the diagnosis of bacterial chronic prostatitis.

Material and methods: We retrospectively examined 895 patients (age range 17-67 years) who met the consensus criteria for clinical chronic prostatitis/chronic pelvic pain syndrome, 50.1% of whom had dysuria and/or perineal discomfort, 37.4% infertility of unknown etiology and 12.5% erectile dysfunction. Segmented urine cultures, including expressed prostatic secretions (EPSs) and semen culture, were performed in all patients.

Results: Of the 895 patients, 182 had significant positive cultures for Gram-negative microorganisms (Escherichia coli was the commonest specimen isolated: 70.4% of cases) and 283 had significant positive cultures for Gram-positive microorganisms. We compared the culture yield in EPS and/or the urine voided after prostatic massage (VB3) sample (four-glass method) with that of the semen sample. In the Gram-negative group, 32 patients were diagnosed by means of semen culture (negative EPS and/or VB3 sample) and in only five cases was a positive diagnosis made despite a negative semen culture (positive EPS and/or VB3 sample). In the remaining subjects, diagnosis was performed with the aid of both EPS/VB3 sample and semen (both of which were positive). In the Gram-positive group, there was significant growth of such microorganisms in semen in every case considered positive, but in only 46 cases was diagnosis achieved via EPS and/or VB3 sample. A diagnosis of chronic prostatitis by Gram-positive microorganisms in these patients was only considered when the same microorganism was retrieved in repeated cultures without previous treatment. Only three cases met such criteria (all of whom had negative EPSs). To evaluate the diagnostic efficiency of the semen and EPS samples, we analyzed their sensitivity and specificity, obtaining higher sensitivity in semen than EPS samples for significant Gram-negative cultures: 97% vs 82.4%. In significant Gram-positive cultures, the sensitivity of semen samples was 100%, compared to only 16.1% for EPS.

Conclusions: A semen sample has higher sensitivity than an EPS for the diagnosis of bacterial chronic prostatitis. In our clinical work-up, first-void urine and a semen culture are considered the only tests necessary to diagnose chronic prostatitis.