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Infectious Arthritis (Including septic arthritis, viral hepatitis and other viral diseases, Lyme disease, etc.)

Contributor: Kevin McKown, MD

CASE 1:

A healthy 18 year old woman presents with a one week history of pain in her hands, wrists and knees. She has no other medical complaints.

She lives in Florida and has no travel history. She works in a daycare. She has never been sexually active. She uses no illicit drugs. She has received all recommended vaccinations.

Her vital signs were as follows: BP 110/60 P 84 RR 14. The patient was in mild distress due to joint pain. General physical examination was normal. Musculoskeletal examination revealed tenderness of several PIP and MCP joints of both hands, both wrists and both knees.

What is your differential diagnosis?

  • In this young woman, infectious causes of arthritis need to be on the top of the differential diagnoses. Included in this list are parvovirus B19, hepatitis B and C virus, reactive arthritis with chlamydia/salmonella/shigella/yersinia, gonococcal arthritis, lyme disease and rubella arthritis. Also included on the differential should be inflammatory arthritis associated with rheumatic disease such as rheumatoid arthritis, systemic lupus erythematosus, and Sjogren’s syndrome to name a few.
  • Her lack of other systemic complaints or changes of inflammatory arthritis on examination make a rheumatic condition unlikely. All of these infections could cause an acute polyarthritis. Hepatitis B and C are unlikely given a lack of identified risk factors and vaccination. Rubella arthritis is unlikely because of vaccination. Lyme disease is unlikely given that she lives in a non-endemic area and has no history of recent travel to an endemic area. Parvovirus will commonly cause arthritis in adults, especially in young women and a rash may not be present. She also has an occupational risk for parvovirus exposure. Parvovirus has a high attack rate and is commonly transmitted to adults by infected children.

CASE 2:

A 65 year old man with hypertension, obesity and benign prostatic hypertrophy presents with a 2 day history of a painful knee. He has no other medical complaints.

His vital signs are BP 144/88, P 92, RR 18, T 38.1 C (100.6 F). He appears to be in mild distress due to knee pain. The general physical exam is only significant for obesity. Musculoskeletal examination reveals crepitus in the right knee. The left knee is red, warm, tender and swollen. Arthrocentesis reveals 40mL of fluid.

Laboratory studies-

CBC- WBC 10,400/uL, hemoglobin 14.5 g/dL, platelets 258,000/uL, differential 80% neutrophils

Synovial Fluid WBC 36,000/uL

92% neutrophils

Gram stain negative

Crystal exam: few weakly birefringent crystals (extra-cellularly)

What is the next best course of action?

This patient has extra-cellular calcium pyrophosphate crystals in his synovial fluid and may have pseudogout as an explanation for his acute monoarthritis; however, pseudogout and infectious arthritis can occur together. The sensitivity of the gram stain for non-gonococcal bacterial arthritis is only around 60% so patients who have a high enough pretest probability for bacterial arthritis need to be treated with appropriate intravenous antibiotics until cultures have returned as negative. This patient had a fever, neutrophilia, a relatively high WBC and high percentage of neutrophils in the synovial fluid, all of which are suggestive of infection. Thus the next best course of action is to treat him for both infection and pseudogout of his knee and NSAIDs, such as naproxen, until the culture results are obtained.. This would include intravenous antibiotics (vancomycin to cover MRSA), repeated drainage of his knee and NSAIDs, such as naproxen until the culture results are obtained.

Patient Care

  1. Recognize the clinical presentations and treatment of bacterial, gonococcal, viral (hepatitis B and C, HIV, Parvovirus B19), Lyme and mycobacterial arthritis.
  2. Describe the steps in performing arthrocentesis of the joints.
  3. Recognize typical synovial fluid test results in bacterial arthritis.
  4. Describe the therapy for bacterial septic arthritis, including initial antibiotic therapy and joint drainage
  5. Describe cultures useful in diagnosing gonococcal arthritis.
  6. Identify the serologic tests useful in diagnosing viral and Lyme arthritis.
  7. Identify radiographic changes suggestive of septic arthritis (1, 2, 3, 4, 5)
  8. Identify skin changes seen in gonococcal arthritis (1, 2) and Lyme’s disease (1, 2, 3).
  9. Identify physical exam, radiographic findings and pathology seen in mycobacterial arthritis (1, 2, 3, 4)

Medical Knowledge

  1. List the most common bacterial organisms causing arthritis in children, adults, IV drug users, and patients with prosthetic joints.
  2. Define host factors that predispose to bacterial arthritis.
  3. Discuss the natural history of untreated bacterial arthritis, gonococcal, viral, Lyme and mycobacterial arthritis
  4. Describe the sensitivity of synovial fluid stains and cultures for bacterial, gonococcal and mycobacterial arthritis.
  5. Relate the epidemiology of Lyme disease (1).

Interpersonal Communication

  1. Explain evaluation, diagnosis, treatment and prognosis to patient and family, using a patient-centered approach.
  2. Summarize case findings when referring to an orthopedic surgeon for surgical drainage.

Professionalism

  1. Demonstrate integrity and honesty in interactions with others.
  2. Serve as a patient advocate.

Problem-based Learning

  1. Identify knowledge deficits regarding infectious arthritis and define a learning plan.
  2. Develop a willingness to recognize mistakes and learn from them.

Systems Based Practice

  1. Effectively engage all medical providers and incorporate different facets of the health system in managing infectious arthritis.
  2. Identify barriers to the delivery of optimal patient care for patients with infectious arthritis.

Keywords: Septic arthritis, Infectious arthritis, Viral arthritis, Bacterial arthritis, Non-gonococcal arthritis, Gonococcal arthritis, Hepatitis C associated arthopathy, Mycobacterial arthritis, Lyme arthritis.

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