Propionibacterium acnes and Staphylococcus lugdunensis Cause Pyogenic Osteomyelitis in an Intramedullary Nail Model in Rabbits

Abstract

b 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.

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.…”

Histological Identification ofPropionibacterium acnesin Nonpyogenic Degenerated Intervertebral Discs

“…Even the positive rates of HE staining were much higher than other staining methods in the detection of Campylobacter pylori in gastric antral biopsies [21]. Brown-Brenn staining is a modified form of Gram-staining used to stain bacteria in tissues directly [22]. It has some advantages over traditional Gram-staining, because the backgrounds created by traditional Gram-staining are so dark that it can be difficult to observe bacteria in tissue.…”

Options and Limitations in Clinical Investigation of Bacterial Biofilms

“…Compared to TEM, it is considered the optimal imaging tool, offering detailed, high-resolution 3D biofilm visualization (217). Staphylococcus lugdunensis and Propionibacterium acnes causing implant-related osteomyelitis in an in vivo animal model were visualized by SEM analysis when present in intercellular aggregates within the bone marrow but not when localized intracellularly (218).…”