M08.027.005 Infectious Arthritis

Suppurative arthritis, a serious joint infection, can cause significant damage and disability if not promptly diagnosed and treated. This guide explores the causes, clinical presentation, diagnosis, and treatment of suppurative arthritis, equipping medical students with the knowledge to effectively manage this condition.

Causes of Suppurative Arthritis

• Bacterial Seeding: Bacteria can reach the joint through the bloodstream (bacteremia) during infections like pneumonia or urinary tract infections.
• Spread from Adjacent Infection: Infections in nearby bones, soft tissues, or bursae can spread to the joint.
• Direct Inoculation: Puncture wounds, surgical procedures, or joint injections can introduce bacteria directly into the joint cavity.

Common Infecting Organisms:

• Gram-positive bacteria: Staphylococcus aureus, Streptococcus species
• Gram-negative bacteria: H. influenzae, Enterobacteriaceae (e.g., E. coli)
• Neisseria gonorrhoeae (gonococcus) – a sexually transmitted infection that can cause septic arthritis

Points to Remember:

• Suppurative arthritis is a medical emergency requiring prompt diagnosis and antibiotic therapy.
• Understanding the route of infection can aid in identifying the causative organism.

Clinical Presentation

Suppurative arthritis typically presents with the following symptoms, often involving large joints like the knee, hip, or shoulder:

• Joint pain: Severe, constant, and worsening with movement.
• Swelling: The affected joint appears visibly swollen and distended.
• Tenderness: Touching or applying pressure to the joint causes significant pain.
• Erythema: The joint appears red and inflamed.
• Limited movement: Joint stiffness and restricted range of motion.

Additional Considerations:

• Fever and chills may be present in some cases.
• Suppurative arthritis is usually monoarticular, affecting only one joint.

Diagnosis

Joint Aspiration:

• A needle is inserted into the joint to withdraw synovial fluid, the lubricating fluid surrounding the joint.
• The aspirated fluid is analyzed for:
  • Clarity: Cloudy fluid indicates inflammation or infection.
  • White blood cell count: Elevated levels suggest infection.
  • Gram stain and culture: Identifying the specific bacteria responsible for the infection is crucial for targeted antibiotic therapy.

Imaging studies: X-rays may be used to assess for joint damage, but often appear normal in the early stages.

Points to Remember:

• Joint aspiration is the cornerstone of diagnosing suppurative arthritis.
• Prompt diagnosis and initiation of antibiotics are crucial to prevent joint destruction.

Treatment

• Antibiotics: Early and aggressive antibiotic therapy is essential to eradicate the infection and prevent joint damage. The choice of antibiotic is guided by the results of gram stain and culture.
• Joint drainage: In some cases, draining pus from the infected joint space may be necessary.
• Pain management: Medications can help manage pain and inflammation.
• Physical therapy: After successful treatment, physical therapy can help regain joint function and mobility.

Points to Remember:

• Rapid intervention with antibiotics is critical to prevent permanent joint damage.
• Treatment may require a multi-disciplinary approach involving infectious disease specialists, orthopedic surgeons, and physical therapists.

Bibliography

• Kumar, Vinay, et al. Robbins and Cotran Pathologic Basis of Disease. Elsevier, 2015.
• Fauci, Anthony S., et al. Harrison’s Principles of Internal Medicine. McGraw-Hill Education, 2018.

Note: This guide is intended for educational purposes only and should not be construed as medical advice. Always consult with a qualified healthcare professional for diagnosis and treatment.