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Abstract 15

Evaluation of the Bacterial Flora of the Prostate Using a 16S rRNA-Based Polymerase Chain Reaction

W Hochreiter, J Duncan, A Schaeffer

Northwestern University Medical School, Department of Urology, Chicago, IL

Introduction The role of bacteria in chronic pelvic pain syndrome (i.e., nonbacterial prostatitis and prostatodynia) is controversial and difficult to assess because the bacterial flora of the prostate is not well defined. Polymerase chain reaction (PCR) is a highly sensitive molecular method for bacterial detection. It can confirm the sterility of tissue with a high level of confidence and detect very small numbers of microbial agents that may represent pathogens. The purpose of this study was to use PCR to determine the bacterial colonization of prostates from presumably healthy men and from those undergoing simple or radical prostatectomy.

Materials and Methods We analyzed 28 prostate samples from 18 organ donors, where the prostate tissue was taken under sterile surgical conditions at the time of organ withdrawal; 14 sterile surgical prostate specimens from 7 patients undergoing radical prostatectomy for prostate cancer who previously had had transrectal biopsies; and 6 sterile surgical specimens from 2 patients who underwent simple prostatectomy for benign prostatic hyperplasia (BPH). The PCR assays utilized 2 different sets of primers to detect bacterial 16S rRNA gene sequences. Normal prostate tissue that had been seeded in vitro with known numbers of E. cold was used to assess the sensitivity of the PCR assays.

Results Only 3 out of 28 organ donor samples showed histological signs of minimal inflammation; all other samples appeared to be normal tissue without evidence of inflammatory reaction. All of these samples were PCR-negative. Among several PCR control reactions, the mixture of prostate tissue seeded with known numbers of E. cold demonstrated the high sensitivity of the assays, allowing detection of as few as 6 bacteria in the presence of 25 mg of prostate tissue. A focal and heterogeneous distribution of inflammation and infection was found in the 14 radical prostatectomy specimens. In both the prostate cancer and the BPH group, there was a strong relationship between the presence of inflammation and positive PCR findings. Three out of 11 samples without inflammation, but all 9 samples with inflammation, were PCR-positive.

Conclusions PCR is a highly sensitive method for detection of bacteria in the prostate. In the present study, negative PCR reactions in prostate tissue from apparently healthy men make the presence of a normal bacterial flora in the prostate extremely unlikely. The presence of bacteria and/or inflammation in radical prostatectomy specimens was found to be a localized process. Concordance between inflammation and positive PCR results in both simple and radical prostatectomy specimens suggests that bacteria frequently may play a role in histologically inflammatory prostatitis.