Infective arthrirtis

Question 1

Define

Answer 1

DEFINITION: joint inflammation resulting from intra-articular infection. Also known as SEPTIC ARTHRITIS.

Question 2

Causes

Answer 2

May be idiopathic

In most cases there is systemic infection allowing for haematogenous spread

Bacteria:
All ages – Staphylococcus aureus, Mycobacterium tuberculosis. <4 years – Streptococcus pneumoniae, Streptococcus pyogenes, Neisseria meningitidis, Gram-negative rods
16–40 years – Mainly Neisseria gonorrhoea

Viruses – Rubella, mumps, HBV, parvovirus B19

Fungi – Candida

Question 3

Risk factors

Answer 3

pre-existing joint disease (especially RhA) DM, immunosuppression, chronic renal failure, recent joint surgery, prosthetic joints, IV drug abuse, ↑age >80 years

Note: infection particularly hard to treat in prosthetic joints

Question 4

Epidemiology

Answer 4

most common in children and elderly

Question 5

Symptoms

Answer 5

Acutely inflamed joint, note: can destroy a joint in under 24 hrs

 Excruciating joint pain, redness, swelling, loss of function

 Usually affects single large joint

(Polyarthritis in immunosuppressed)

 Fever
TB arthritis is more insidious and chronic

Question 6

Signs

Answer 6

• Painful, hot, swollen, immobile joint with overlying erythema
• Serve pain prevents passive movement
• Pyrexia

Question 7

Investigations

Answer 7

Joint Aspiration (IMPORTANT)

• In infective arthritis, the aspirate will be grossly purulent
• Send synovial fluid for MC&S

Microscopy - rule out crystal arthritis

• PCR may be used if a viral cause is suspected

Bloods

• FBC - high WCC, high neutrophils
• High CRP and ESR
• Blood cultures - MC&S
• Viral serology may be useful

Plain Joint Radiographs

• Affected joint may look normal initially
• Can show signs of damage following the infection

MRI Scan

• Useful for detecting osteomyelitis