Propionibacterium acnes is a colonizer of the lipid-rich
sebaceous glands of the skin. The pathogenicity of P. acnes has long been
restricted to skin conditions. Its isolation from other anatomical sites or
deep microbiological samples has often been considered as contamination. It is
involved in the inflammation process of acne is well known, but until recently,
it was neglected in other clinical presentations. P. acnes has been considered
to be of low virulence, but the new genomic, transcriptomic, and phylogenetic
studies have allowed better understanding of this potential pathogen's
importance in causing many chronic and recurrent infections, including
orthopedic ( osteo-articular and spine )
and cardiac prosthetic, and breast or eye implant-infections, and
neurosurgical infections of external ventricular shunts.
Hip Joint implant
These
infections, are facilitated by the ability of P. acnes to produce a biofilm, requiring using anti-biofilm active antibiotics
such as rifampicin. However, in the last 10 years, the rate of
antibiotic-resistant bacteria has increased, especially for macrolides and
tetracyclines. The antimicrobial susceptibility of P. acnes is not routinely performed in microbiology laboratories
because of its susceptibility to a wide range of antibiotics.
Some
antibiotics should be tested to adapt treatment because of the prevalence of
antibiotic resistance in P. acnes: tetracycline, erythromycin, clindamycin, and
cotrimoxazole. Furthermore, other antibiotics should be tested for severe
infections, to optimize treatment and obtain a synergistic effect against P. acnes: penicillin, cephalosporins,
vancomycin, quinolones, rifampicin, and the “new” antibiotics such as
linezolid, daptomycin, and tigecycline, to which P. acnes is usually
susceptible. Aminoglycosides and metronidazole are not active against P. acnes.
The
treatment of severe infections caused by P. acnes includes a combination of
antibiotics, administrated intravenously initially, and usually associated with
optimal surgery (e.g., removal of the device and/or debridement of the surgical
site). Penicillin G and ceftriaxone are still considered as first-line
antibiotics for severe infections. Clindamycin, tetracycline, and levofloxacin
are alternatives in those allergic to beta-lactams. Rifampicin and daptomycin
are also active antimicrobial agents, effective also against P. acnes biofilm. Removal of the device
associated with the infection is usually sufficient to reduce the inoculum
causing chronic infection.
Gram stain of Propionibacterium acnes
