Propionibacterium acnes: from commensal to opportunistic biofilm-associated implant pathogen

Abstract

Propionibacterium acnes is known primarily as a skin commensal. However, it can present as an opportunistic pathogen via bacterial seeding to cause invasive infections such as implant-associated infections. These infections have gained more attention due to improved diagnostic procedures, such as sonication of explanted foreign materials and prolonged cultivation time of up to 14 days for periprosthetic biopsy specimens, and improved molecular methods, such as broad-range 16S rRNA gene PCR. Implant-associated infections caused by P. acnes are most often described for shoulder prosthetic joint infections as well as cerebrovascular shunt infections, fibrosis of breast implants, and infections of cardiovascular devices. P. acnes causes disease through a number of virulence factors, such as biofilm formation. P. acnes is highly susceptible to a wide range of antibiotics, including beta-lactams, quinolones, clindamycin, and rifampin, although resistance to clindamycin is increasing. Treatment requires a combination of surgery and a prolonged antibiotic treatment regimen to successfully eliminate the remaining bacteria. Most authors suggest a course of 3 to 6 months of antibiotic treatment, including 2 to 6 weeks of intravenous treatment with a beta-lactam. While recently reported data showed a good efficacy of rifampin against P. acnes biofilms, prospective, randomized, controlled studies are needed to confirm evidence for combination treatment with rifampin, as has been performed for staphylococcal implant-associated infections.

Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Figures

FIG 1

Relative abundances of Propionibacterium species in different skin areas determined by 16S rRNA gene sequence analysis of 10 individuals. Blue, sebaceous gland; red, dry areas; green, moist areas. +++, relative abundance of >50%; ++, relative abundance of ≥5 to ≤50%; +/−, relative abundance of

FIG 2

Scanning electron micrographs of a P. acnes strain ATCC 11827 biofilm on solid soda lime glass beads (Walter Stern Inc., Port Washington, NY), incubated with P. acnes for 2 days anaerobically at 37°C under static conditions (magnifications, ×2,000 [A] and ×20,000 [B]; beam accelerating voltage, 1 kV; working distance, 3 mm) (Zeiss Supra 55VP field emission scanning electron microscope).

FIG 3

Scanning electron micrographs of a P. acnes strain ATCC 11827 biofilm on a biofilm-coated 0.25-mm-diameter stainless steel insect pin, incubated with P. acnes for 2 days anaerobically at 37°C under static conditions (magnifications, ×371 [A], ×352 [B], and ×33,800 [C]; beam accelerating voltage, 1 kV; working distance, 5 mm) (Zeiss Supra 55VP field emission scanning electron microscope).

FIG 4

Left shoulder PJI with abscess formation in an 82-year-old woman 3 months after primary shoulder arthroplasty. Shown is clinical presentation (A and B) with sudden swelling and pain above left acromioclavicular joint without radiological signs of osteolysis or loosening of the implant (C and D) but with a 2.8- by 1-cm large fluid collection periarticular (E) (A, acromion; C, clavicula). P. acnes was cultivated in 2 of 2 joint aspirates, 1 of 3 tissue biopsy specimens, and sonication fluid of the mobile part of the implant (>500 CFU/ml). (Courtesy of M. Clauss, Liestal, Switzerland.)

FIG 5

Pacemaker endocarditis 15 years after pacemaker revision surgery in a 58-year-old man. Shown are a large vegetation (3.5 by 5 cm) on the pacemaker lead (A) and an echogenic mass (EM) in the right ventricle (RV) seen by transesophageal echocardiography (B and C). P. acnes endocarditis was diagnosed by conventional tissue culture and broad-spectrum PCR of the vegetation around the pacemaker lead. RA, right atrium. Blue-green arrows show pacemaker leads in the cross section. (Courtesy of C. Starck, Zurich, Switzerland.)