Septic arthritis caused by Peptostreptococcus asaccharolyticus

Peptostreptococcus spp are commensal organisms, usually involved in periodontal disease. Peptostreptococcus asaccharolyticus is an anaerobic gram-negative cocci, difficult to isolate due to its slow growth. Septic arthritis by this microorganism is a rare entity, but it can occur by hematogenous dissemination from a distant focus. Colonization and growth are more likely to occur in an already damaged articulation. We report the case of a 57 year-old woman with peripheral spondyloarthritis who developed knee septic arthritis by Peptostreptococcus asaccharolyticus.