Identification of Propionibacterium acnes by polymerase chain reaction for amplification of 16S ribosomal RNA and lipase genes

Propionibacterium acnes belongs to the cutaneous flora and is present in sebaceous follicles. The fatty acids that are released from sebum triglycerides by the action of this bacterial lipase play an important role in the pathogenesis of acne vulgaris. P. acnes is also involved in postoperative disorders and opportunistic infections in immunosuppressed hosts. Recently, it has been proposed that P. acnes causes sarcoidosis. Therefore, rapid isolation and identification of P. acnes is important. This study evaluated the polymerase chain reaction (PCR) for the detection of the 16S rRNA and lipase genes of P. acnes. The PCR used to detect the 16S rRNA gene could amplify the gene of P. acnes, but not the genes of the other tested strains of P. avidum, P. granulosum, P. lymphophilum, P. jensenii, P. acidipropionici and P. thoenii. The PCR to detect the lipase gene of P. acnes, however, could amplify not only the gene of P. acnes but also that of P. avidum. The PCR product of this lipase gene was not found in the strains of the other species tested. Therefore, the organism that has both the 16S rRNA gene and lipase gene was identified as P. acnes, while the strain with the lipase gene but not the 16S rRNA gene of P. acnes was characterized as P. avidum. These findings were confirmed by the conventional biochemical tests including lipase activity. Furthermore, out of the seven clinical isolates from acne vulgaris, four were identified as P. acnes and three as P. avidum by the PCR method and biochemical tests. The combination of two PCR, one for the detection of the 16S rRNA and the other of lipase genes was shown to be an easier, faster and more accurate method to identify P. acnes and P. avidum than conventional methods.