Although two phenotypes of the opportunistic pathogen Propionibacterium acnes (types I and II) have been described, epidemiological investigations of their roles in different infections have not been widely reported. Using immunofluorescence microscopy with monoclonal antibodies (MAbs) QUBPa1 and QUBPa2, specific for types I and II, respectively, we investigated the prevalences of the two types among 132 P. acnes isolates. Analysis of isolates from failed prosthetic hip implants (n ‫؍‬ 40) revealed approximately equal numbers of type I and II organisms. Isolates from failed prosthetic hip-associated bone (n ‫؍‬ 6) and tissue (n ‫؍‬ 38) samples, as well as isolates from acne (n ‫؍‬ 22), dental infections (n ‫؍‬ 8), and skin removed during surgical incision (n ‫؍‬ 18) were predominately of type I. A total of 11 (8%) isolates showed atypical MAb labeling and could not be conclusively identified. Phylogenetic analysis of P. acnes by nucleotide sequencing revealed the 16S rRNA gene to be highly conserved between types I and II. In contrast, sequence analysis of recA and a putative hemolysin gene (tly) revealed significantly greater type-specific polymorphisms that corresponded to phylogenetically distinct cluster groups. All 11 isolates with atypical MAb labeling were identified as type I by sequencing. Within the recA and tly phylogenetic trees, nine of these isolates formed a cluster distinct from other type I organisms, suggesting a further phylogenetic subdivision within type I. Our study therefore demonstrates that the phenotypic differences between P. acnes types I and II reflect deeper differences in their phylogeny. Furthermore, nucleotide sequencing provides an accurate method for identifying the type status of P. acnes isolates.Propionibacterium acnes is an opportunistic pathogen implicated in late-stage prosthetic joint infections, acne vulgaris, endocarditis, endophthalmitis, osteomyelitis, and shunt-associated central nervous system infections (2,5,7,33). Currently, routine diagnostic practices may underestimate the clinical importance of this anaerobic organism due to inefficient detection and isolation procedures, along with the traditionally held view that, due to its low virulence, its presence in clinical samples reflects contamination. While the opportunistic pathogenic potential of coagulase-negative staphylococci (CoNS), such as Staphylococcus epidermidis, is well recognized, the importance of P. acnes may still be overlooked (13), despite the fact that it produces more kinds of putative virulence determinants than CoNS (5, 38). This fact is illustrated by recent studies in which P. acnes was recovered as frequently as CoNS from the prosthetic hips of patients undergoing revision arthroplasty (33, 34).As a member of the resident human microbiota, P. acnes is found predominantly in the sebaceous gland-rich areas of the skin in adults (5, 25). It has, however, also been isolated from the conjunctiva, the mouth, and the large intestine (7). It accounts for approximately half of the total skin microb...

Bacteria of the normal skin microbiota such as Propionibacterium acnes and coagulase-negative staphylococci often are dismissed as contaminants when detected in clinical samples. Propionibacterium acnes is described as a cause of spinal infection and more recently has been linked to sciatica. To date no researchers formally have examined the incidence of bacterial wound contamination during spinal surgery. Surgical specimens were removed from 79 patients having spinal surgery for analysis using agar culture detection, broth enrichment, and immunofluorescence microscopy. Bacteria were identified in 29.1% of skin samples, 21.5% of tissue samples and 16.5% of washings retrieved from operative wounds. Propionibacterium acnes was identified more frequently than Staphylococcus spp in each of the three sample types. Bacteria were detected using enrichment in 9 (11%) patients and using fluorescence microscopy in 15 (19%). The results of immunofluorescence microscopy suggest that Propionibacterium acnes detected in wounds originates from patient skin. Bacteria from contaminated wounds appeared as single cells using fluorescence microscopy; however previous work shows that bacteria from infected hip prosthesis are observed as large aggregates. Therefore, it is suggested that immunofluorescence microscopy is a useful tool to help discriminate between surgical contamination and infection. Level of Evidence: Diagnostic study, Level I (prospective study). See the Guidelines for Authors for a complete description of levels of evidence.

Antisepsis of the skin with the sequential application of PVI and CHG more effectively reduces the contamination of a surgical wound than PVI alone. Cite this article: 2017;99-B:1354-65.