Delayed Propionibacterium acnes surgical site infections occur only in the presence of an implant

Abstract

Whether Propionibacterium acnes (P. acnes) causes surgical-site infections (SSI) after orthopedic surgery is controversial. We previously reported that we frequently find P. acnes in intraoperative specimens, yet none of the patients have clinically apparent infections. Here, we tracked P. acnes for 6 months in a mouse osteomyelitis model. We inoculated P. acnes with an implant into the mouse femur in the implant group; the control group was treated with the bacteria but no implant. We then observed over a 6-month period using optical imaging system. During the first 2 weeks, bacterial signals were detected in the femur in the both groups. The bacterial signal completely disappeared in the control group within 28 days. Interestingly, in the implant group, bacterial signals were still present 6 months after inoculation. Histological and scanning electron-microscope analyses confirmed that P. acnes was absent from the control group 6 months after inoculation, but in the implant group, the bacteria had survived in a biofilm around the implant. PCR analysis also identified P. acnes in the purulent effusion from the infected femurs in the implant group. To our knowledge, this is the first report showing that P. acnes causes SSI only in the presence of an implant.

Immunoproteomic Identification ofIn Vivo-Produced Propionibacterium acnes Proteins in a Rabbit Biofilm Infection Model

“…This observation is also similar to the findings of the two nonhematogenous studies that required a high inoculum of 10 7 to 10 8 to achieve chronic infection (34,35). The clinical strain RMA 13884 in this study was chosen since (i) it was relevant and recently isolated from a clinical case of spinal osteomyelitis with hardware, and (ii) it matched the 1A lineage with the P. acnes laboratory strain from the ATCC that has been used in multiple in vitro studies (10,11).…”

“…Current animal models for P. acnes bone infections associated with an implant are limited to a hematogenous infection model of total knee arthroplasties (33), an implant-associated osteomyelitis model in rabbits (34), and a bone implant model in BALB/c mice (35). These studies examined the capability of P. acnes to establish chronic infections but did not evaluate the in vivo protein expression of P. acnes and/or the host humoral response.…”

Propionibacterium acnes as an emerging pathogen in skull base osteomyelitis: A case series

“…P. acnes infections have been reported in the orthopedic literature, particularly after shoulder surgery, although there is some controversy over whether this phenomenon is only associated with surgical implants . The virulence of this commensal bacterium is thought to be due to its ability to form biofilms and its production of a number of enzymes that can destroy host tissue .…”

Bacterial Infection of Spine Instrumentation and Microbial Influenced Corrosion (MIC): Chicken or Egg

“…There is evidence that microbes including bacteria and macrophages are associated with in the presence biomedical alloys implants for orthopedic procedures [1][2][3][4]. The corrosion of metal alloys (A316L Surgical stainless steel; ASTM F136 ELI Ti6Al4V; ASTM F75/F1537/F799 CoCrMoC) in-vivo has also been well documented [5][6][7][8].…”

“…were shown to be associated with orthopedic infections, where it was detected in 63% of sonicated samples taken from 120 patients receiving total hip revision [4]. As recently as 2016, P. acnes were highlighted as a possible contributor to post operative infections in orthopedic procedures [1]. These commensal skin dwelling microbes are anaerobic, sulfur reducing bacteria [11][12][13].…”