Septic arthritis due to Aerococcus viridans.

Area of Science:

• Microbiology
• Infectious Diseases
• Orthopedics

Background:

• Septic arthritis is a serious joint infection requiring prompt diagnosis and treatment.
• Aerococcus viridans is a gram-positive bacterium rarely implicated in human infections, primarily endocarditis and osteomyelitis.
• Distinguishing Aerococcus viridans from morphologically similar bacteria like Streptococcus viridans is crucial for accurate diagnosis.

Observation:

• A 20-year-old woman presented with septic arthritis of the hip.
• The causative agent was identified as Aerococcus viridans based on its characteristic formation of gram-positive tetrads in broth cultures.
• This presentation is distinct from the typical chain formation observed in Streptococcus species.

Findings:

• This case represents the first documented instance of septic arthritis of the hip caused by Aerococcus viridans.
• The identification highlights the importance of considering less common pathogens in septic arthritis.
• Microscopic morphology (tetrads vs. chains) is a key differentiator between Aerococcus and Streptococcus species.

Implications:

• Clinicians should consider Aerococcus viridans in the differential diagnosis of septic arthritis, especially when Gram stains show cocci in tetrads.
• Further research is needed to understand the pathogenicity and clinical spectrum of Aerococcus viridans infections.
• Accurate identification of Aerococcus viridans is essential for appropriate antimicrobial therapy and patient management.