The microbiome bone axis in osteomyelitis: integrating evidence from bone oral and gut microbiota

Osteomyelitis is an inflammatory bone disorder that includes both infectious and noninfectious forms and remains a major cause of bone destruction, impaired skeletal repair, and long-term disability. Although bacterial infection is the predominant cause, disease progression is influenced by interactions among microorganisms, host immunity, inflammation, and bone remodeling. This review critically evaluates current evidence from genome-wide association and Mendelian randomization studies, clinical investigations, and experimental animal models. Clinical studies demonstrate that osteomyelitic bone contains polymicrobial communities enriched with anaerobic and biofilm-forming bacteria, whereas oral microbial dysbiosis differs between chronic bacterial and chronic nonbacterial osteomyelitis. Experimental studies indicate that gut microbial dysbiosis is associated with impaired intestinal barrier function, altered microbial metabolites, systemic inflammation, and delayed bone repair. Current evidence therefore suggests that microbial communities detected at local sites are associated with infection, biofilm formation, and local inflammatory responses, whereas the gut microbiome may influence systemic immunity, inflammatory tone, and bone remodeling. Although microbiome-targeted interventions have shown beneficial effects in experimental models, current evidence remains largely associative, and mechanistic and longitudinal studies are limited. A better understanding of microbiome-host interactions may facilitate the development of microbiome-based strategies for the prevention and treatment of osteomyelitis.