Plate-associated localized osteitis in mini-pig by biofilm-forming Methicillin-resistant Staphylococcus aureus (MRSA): establishment of a novel experimental model

Efficacy of lysostaphin-coated titanium plates on implant-associated MRSA osteitis in minipigs

PURPOSE

The growing incidence of implant-associated infections (IAIs) caused by biofilm-forming Staphylococcus aureus in combination with an increasing resistance to antibiotics requires new therapeutic strategies. Lysostaphin has been shown to eliminate this biofilm. Own studies confirm the effectiveness in a murine model. The current study characterizes the effects of lysostaphin-coated plates in an IAI minipig model.

METHODS

The femur of 30 minipigs was stabilized with a five-hole plate, a bone defect was created, and in 20 cases methicillin-resistant Staphylococcus aureus was applied. Ten animals served as control group. After 14 days, local debridement, lavage, and plate exchange (seven-hole plate) were performed. Ten of the infected minipigs received an uncoated plate and 10 a lysostaphin-coated plate. On day 84, the minipigs were again lavaged, followed by euthanasia. Bacterial load was quantified by colony-forming units (CFU). Immunological response was determined by neutrophils, as well as interleukins. Fracture healing was assessed radiologically.

RESULTS

CFU showed significant difference between infected minipigs with an uncoated plate and minipigs with a lysostaphin-coated plate (p = 0.0411). The infection-related excessive callus formation and calcification was significantly greater in the infected animals with an uncoated plate than in animals with a lysostaphin-coated plate (p = 0.0164/p = 0.0033). The analysis of polymorphonuclear neutrophils and interleukins did not reveal any pioneering findings.

CONCLUSION

This study confirms the minipig model for examining IAI. Furthermore, coating of plates using lysostaphin could be a promising tool in the therapeutic strategies of IAI. Future studies should focus on coating technology of implants and on translation into a clinical model.

Choosing the right animal model for osteomyelitis research: Considerations and challenges

Osteomyelitis is a debilitating bone disorder characterized by an inflammatory process involving the bone marrow, bone cortex, periosteum, and surrounding soft tissue, which can ultimately result in bone destruction. The etiology of osteomyelitis can be infectious, caused by various microorganisms, or noninfectious, such as chronic nonbacterial osteomyelitis (CNO) and chronic recurrent multifocal osteomyelitis (CRMO). Researchers have turned to animal models to study the pathophysiology of osteomyelitis. However, selecting an appropriate animal model that accurately recapitulates the human pathology of osteomyelitis while controlling for multiple variables that influence different clinical presentations remains a significant challenge. In this review, we present an overview of various animal models used in osteomyelitis research, including rodent, rabbit, avian/chicken, porcine, minipig, canine, sheep, and goat models. We discuss the characteristics of each animal model and the corresponding clinical scenarios that can provide a basic rationale for experimental selection. This review highlights the importance of selecting an appropriate animal model for osteomyelitis research to improve the accuracy of the results and facilitate the development of novel treatment and management strategies.