Septic arthritis caused by Peptostreptococcus asaccharolyticus

Area of Science:

• Microbiology
• Rheumatology
• Infectious Diseases

Background:

• Peptostreptococcus spp are commensal anaerobic bacteria often implicated in periodontal disease.
• Peptostreptococcus asaccharolyticus is a gram-negative coccus known for slow growth, complicating its isolation and identification.
• Septic arthritis caused by this bacterium is uncommon, typically arising from hematogenous spread from a remote infection site.

Observation:

• A 57-year-old woman with a history of peripheral spondyloarthritis presented with knee septic arthritis.
• The affected knee joint was colonized and infected by Peptostreptococcus asaccharolyticus.

Findings:

• The diagnosis of septic arthritis was confirmed in the patient.
• Peptostreptococcus asaccharolyticus was identified as the causative pathogen, despite its fastidious growth requirements.
• The infection likely occurred due to hematogenous dissemination to an already compromised joint.

Implications:

• This case underscores the importance of considering rare pathogens like Peptostreptococcus asaccharolyticus in the differential diagnosis of septic arthritis, particularly in immunocompromised or chronically ill patients.
• Early and accurate identification of the causative agent is crucial for effective treatment and management of septic arthritis.
• Further research may elucidate the specific mechanisms by which Peptostreptococcus asaccharolyticus colonizes and infects joint tissues, especially in the context of underlying inflammatory conditions.