An evaluation of PCR primer sets used for detection of Propionibacterium acnes in prostate tissue samples.

BACKGROUND: Multiple studies have now shown that Propionibacterium acnes can be cultured from post-prostatectomy derived prostate tissue samples. In contrast, both universal eubacterial 16S rDNA PCR and P. acnes-specific 16S rDNA PCR have failed to detect this organism at a frequency similar to that of bacterial culture. A potential explanation for this discrepancy, proposed by Cohen et al., involves mismatches in 16S rDNA primer sets used for bacterial detection.
METHODS: The sensitivity of both a previously published P. acnes-specific primer set containing a potential mismatch and a new primer set with no mismatches was determined. Both primer sets were used to interrogate two sets of DNA samples derived from post-prostatectomy prostate tissues that differed in the level of sterile precautions maintained during tissue collection.
RESULTS: The number of P. acnes positive samples was associated with the sterility of the sample collection process. In all instances, positive samples were determined to reflect low cell numbers (<10 CFU).
CONCLUSIONS: Although the results of previous studies have shown that P. acnes is not the only organism potentially present in the prostates of prostate cancer patients, mismatches in PCR primer sets may have also influenced the sensitivity of P. acnes detection. When using PCR in determining the presence of P. acnes in the human prostate, care should be taken to establish the potential influence of exogenous contamination and, due to the sensitivity of the assay, samples exposed to the urethra during the collection process (prostatic secretions, TURP specimens) should not be used.