Septic Arthritis

Question 1

What are the sources of infection of the joint?

Answer 1

• hematogenous spread from a distant focus of infection
• direct seeding by local trauma/ injury
• extension of an infection of overlying soft tissue/ bone

Question 2

Inflammation from joint infection rapidly destroys ________

Answer 2

articular cartilage

Question 3

What are the most common organisms that cause septic arthritis?

Answer 3

• gram positives like strep, staph are most common
• gram negatives in high risk patients
• IVDU= polymicrobial, anaerobes

Question 4

Differentiate gonococcal reactive arthritis vs gonococcal septic arthritis

Answer 4

1. Gonococcal Reactive Arthritis
   - Multiple joints involved
   - Typically affects wrists/hands
   - Skin rash usually evident
   - Rare to find organisms in the synovial fluid
2. Gonococcal Septic Arthritis
   - Monoarthritis
   - Wrists/hands rarely involved
   - Knees primarily involved
   - Gonococci found in both synovial fluid and blood
   - Skin lesions may be present over the affected joint but widespread rashes rare

Question 5

What are some risk factors that should alert the clinician to the possibility of septic arthritis?

Answer 5

• acute monoarthritis
• knee in adults/ hip in children
• history of recent infection, travel, IVDU

Question 6

Septic arthritis of the ____ often indicates severe underlying disease

Answer 6

shoulder

Question 7

What are classic symptoms of septic arthritis?

Answer 7

acute pain in the joint
restricted movement
swelling and erythema around the joint
signs of systemic infection

Question 8

Describe the appearance of synovial fluid from a septic joint

Answer 8

turbid, yellow, decreased viscosity

Question 9

What lab findings on synovial fluid suggest septic arthritis?

Answer 9

• positive gram stain
• cells 50-150k, mostly neutrophils
• decreased glucose

Question 10

What other samples should be taken for microbiological investigation?

Answer 10

blood, urine, throat culture, swab any lesions

if suspected, look for Lyme, syphilis, brucellosis

Question 11

What findings might be present on X ray in septic arthritis?

Answer 11

fluid in joint
joint space widening
soft tissue swelling

Question 12

Empiric therapy for septic arthritis should target ______

Answer 12

S. aureus

Question 13

What groups are considered high risk for gram negatives or anaerobes as the cause of septic arthritis?

Answer 13

diabetics
RS
IVDU
catheter related bloodstream infections
prosthetic joints

Question 14

What is an appropriate antibiotic regimen for a patient with septic arthritis and no specific risk factors for atypical infection?

Answer 14

high dose IV nafcillin/ vancomycin

Question 15

What is an appropriate antibiotic regimen for a high risk patient with septic arthritis

Answer 15

• High-dose IV nafcillin plus either an aminoglycoside or a fluoroquinolone
  or
• A second-generation cephalosporin

Question 16

If a patient has gonococcal arthritis, they must also be treated for ______

Answer 16

chlamydia

Question 17

_________ is critical to preserving joint function after septic arthritis

Answer 17

physical therapy