Related Experiment Video
Updated: May 2, 2026
In Vivo Mouse Model of Spinal Implant Infection
Published on: June 23, 2020
Propionibacterium acnes and Staphylococcus lugdunensis cause pyogenic osteomyelitis in an intramedullary nail model
Abhay Deodas Gahukamble1, Andrew McDowell, Virginia Post
1AO Research Institute Davos, Davos, Switzerland.
Abstract:
Propionibacterium acnes and coagulase-negative staphylococci (CoNS) are opportunistic pathogens implicated in prosthetic joint and fracture fixation device-related infections. The purpose of this study was to determine whether P. acnes and the CoNS species Staphylococcus lugdunensis, isolated from an "aseptically failed" prosthetic hip joint and a united intramedullary nail-fixed tibial fracture, respectively, could cause osteomyelitis in an established implant-related osteomyelitis model in rabbits in the absence of wear debris from the implant material. The histological features of P. acnes infection in the in vivo rabbit model were consistent with localized pyogenic osteomyelitis, and a biofilm was present on all explanted intramedullary (IM) nails. The animals displayed no outward signs of infection, such as swelling, lameness, weight loss, or elevated white blood cell count. In contrast, infection with S. lugdunensis resulted in histological features consistent with both pyogenic osteomyelitis and septic arthritis, and all S. lugdunensis-infected animals displayed weight loss and an elevated white blood cell count despite biofilm detection in only two out of six rabbits. The differences in the histological and bacteriological profiles of the two species in this rabbit model of infection are reflective of their different clinical presentations: low-grade infection in the case of P. acnes and acute infection for S. lugdunensis. These results are especially important in light of the growing recognition of chronic P. acnes biofilm infections in prosthetic joint failure and nonunion of fracture fixations, which may be currently reported as "aseptic" failure.
Insights
Propionibacterium acnes causes low-grade osteomyelitis in rabbits, forming biofilms but showing no outward signs of infection. Staphylococcus lugdunensis causes acute infection with systemic signs, even without widespread biofilm formation.
Area of Science:
- Orthopedics
- Infectious Diseases
- Microbiology
Background:
- Propionibacterium acnes and coagulase-negative staphylococci (CoNS) are linked to implant-related infections.
- Distinguishing between aseptic failure and subtle infections is clinically challenging.
Purpose of the Study:
- To investigate the osteomyelitis-causing potential of P. acnes and Staphylococcus lugdunensis in a rabbit implant model.
- To differentiate the infection characteristics of these bacteria in the absence of wear debris.
Main Methods:
- Rabbits with implanted intramedullary nails were infected with P. acnes or S. lugdunensis.
- Histological analysis and clinical observations were used to assess infection severity.
- Biofilm presence on explanted devices was evaluated.
Main Results:
- P. acnes infection led to localized osteomyelitis and biofilm formation, with no systemic signs in rabbits.
- S. lugdunensis infection caused pyogenic osteomyelitis and septic arthritis, with systemic signs like weight loss and elevated white blood cell count.
- Biofilm was detected on all P. acnes-infected nails but only in two S. lugdunensis-infected rabbits.
Conclusions:
- P. acnes causes a low-grade, biofilm-mediated osteomyelitis, potentially explaining "aseptic" implant failures.
- S. lugdunensis induces an acute, systemic infection, presenting differently from P. acnes.
- These findings highlight the distinct pathogenic mechanisms of these bacteria in implant-related infections.
