Chronic prostatic infection and inflammation by Propionibacterium acnes in a rat prostate infection model

PLoS One. 2012;7(12):e51434. doi: 10.1371/journal.pone.0051434. Epub 2012 Dec 11.


Chronic inflammation in the prostate, seen as infiltration of inflammatory cells into the prostate gland in histological samples, affects approximately half the male population without indication of prostate disease, and is almost ubiquitous in patients diagnosed with benign prostate hyperplasia and cancer. Several studies have demonstrated the gram-positive bacterium Propionibacterium acnes to be frequently present in prostate tissue from men suffering from prostate disease. P. acnes has been shown to be associated with histological inflammation in human prostatectomy specimens, and also to induce strong inflammatory response in prostate-derived tissue culture models. The present paper describes a rat model for assessment of the pathogenic potential of P. acnes in prostate. Prostate glands of Sprague Dawley rats (n = 98) were exposed via an abdominal incision and live P. acnes or, in control rats, saline were injected into the ventral and dorso-lateral lobes. Rats were sacrificed 5 days, 3 weeks, 3 months and 6 months post infection, and prostate tissue was analyzed for bacterial content and histological inflammation. Rat sera were assessed for levels of CRP and anti-P. acnes IgG. Live P. acnes could be recovered from the dorso-lateral lobes up to 3 months post infection, while the ventral lobes were cleared from bacteria at that time. In samples up to 3 months post infection, the dorso-lateral lobes exhibited intense focal inflammation. CRP and IgG levels were elevated throughout the span of the experiment, and reached maximum levels 3 weeks and 3 months post infection, respectively. We show that P. acnes have the potential to cause chronic infection in previously healthy prostate, and that the infection has potential to cause chronic histological inflammation in the infected tissue. The high prevalence of P. acnes in human prostate tissue calls for resolution of pathogenic details. The present rat model suggests that complications such as chronic inflammation may be induced by P. acnes infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Bacterial / blood
  • Chronic Disease
  • Disease Models, Animal
  • Humans
  • Immunoglobulin G / blood
  • Inflammation* / microbiology
  • Inflammation* / physiopathology
  • Male
  • Propionibacterium acnes / pathogenicity
  • Prostate* / microbiology
  • Prostate* / physiopathology
  • Prostatic Diseases* / microbiology
  • Prostatic Diseases* / physiopathology
  • Prostatic Hyperplasia* / microbiology
  • Prostatic Hyperplasia* / pathology
  • Rats
  • Rats, Sprague-Dawley


  • Antigens, Bacterial
  • Immunoglobulin G

Grants and funding

This study was funded by grants from the County Council of Västerbotten (ALF), (FE), the Medical Faculty of Umeå University (FE), the Lions Cancer Research Foundation and Cancerforskningsfonden Norrland (JO, FE), Percy Falks Stiftelse för forskning beträffande prostatacancer och bröstcancer (JO), and Svenska Läkaresällskapet (SLS-173871, SLS-248771) (JO). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.