Intracellular infection of Cutibacterium acnes in macrophages of extensive peri‐implantitis lesions: A clinical case series

Abstract

AbstractCutibacterium acnes is a facultative anaerobic, gram‐positive rod, and a commensal bacterium of the body surface including oral cavity. A causal relationship between C. acnes and chronic granulomatous diseases, such as sarcoidosis and orthopedic implant‐associated infections, has been previously reported. Typically, C. acnes has been observed inside macrophages, allowing evasion of host immunity, and triggering a persistent inflammatory response. However, such findings have not been reported in peri‐implantitis lesions. In this case series, we collected inflamed tissues from extensive peri‐implantitis lesions of eight patients. Out of the eight samples, seven tested positive for the 16 s rRNA gene of C. acnes by polymerase chain reaction, and six were positive by immunohistochemistry. Immunohistochemical staining revealed the presence of C. acnes in the cytoplasm of macrophages, suggesting a role in lesion formation. This finding may enhance our understanding of the pathophysiology of persistent peri‐implantitis lesions and provide implications for future therapy.