Infections of Bones and Joints

Question 1

symptoms of septic arthritis

Answer 1

• hot swollen joints
• can lead to irreversible joint damage
• resistance to conventional antibiotics is increasing in these cases
  1. Isolation of a pathogenic organism from an infected joint
  2. isolation of a pathogenic organism from another source in the context of a hot red joint suspicious of sepsis
  3. typical clinical features and turbid joint fluid in the presence of previous antibiotic treatment
  4. post-mortem or pathological features and suspicious of septic arthritis

Question 2

what is a typical presentation of septic arthritis

Answer 2

1-2 weeks of a red painful and restricted joint
large joints/typically in the leg, knee and lumbosacral spine
if preexisting arthritis the joint will show signs out of proportion to disease
low virulence causative organisms and fungal and mycobacterial infections can delay presentation

Question 3

what are the casative organisms for septic arthritis

Answer 3

• S.aureus
• S.pyogenes
• S.epidermidis
• M.tuberculosis
• Salmonella
• Brucella(fromunpasteuriseddairyproducts),
• Don’t forget Neisseria gonorrhoeae in sexually active
• Kingella can cause infections in children
• Pasturella can cause infections in animal bites

Question 4

what are some predisposing conditions which can increase the likelyhood of septic arthritis

Answer 4

• Rheumatoid arthritis or osteoarthritis
• Joint prosthesis
• Intravenousdrugabuse
• Alcoholism
• Diabetes
• Previous intra-articular corticosteroid injection
• Cutaneous ulcers

Question 5

how can the infection be introduced to the joint

Answer 5

– haematogenous spread

– direct inoculation e.g. trauma or iatrogenically.

Question 6

Reactive arthritis

Answer 6

• classic triad conjunctivitis, urethritis, and arthritis
  • Occurring after an infection e.g. urogenital or GI tract.
  • Epidemiologically, the disease is more common in men
  • HLA-B27 is associated with reactive arthritis
  • Dermatologic manifestations
  – keratoderma blennorrhagicum
  – circinate balanitis
  – ulcerative vulvitis
  – nailchanges
  – oral lesions

Question 7

reactive arthritis organisms

Answer 7

– Chlamydia trachomatis
– Shigella flexneri
– Salmonella enteritidis/typhimurium/muenchen

Reactive arthritis may be treated with full dose NSAID with gastric protection and treatment of precipitating factors e.g. Chlamydia

Question 8

Osteomyelitis

Answer 8

inflammation of the bone and bone marrow usually caused by pyogenic bacteria, and rarely by mycobacteria or fungi

Question 9

what causes infection in osteomyelitis

Answer 9

• Haematogenous spread • Local spread (from septic
arthritis)
• Compound fracture (open)
• Foreign body

Question 10

Predisposition to Osteomyelitis

Answer 10

organism and the predisposition it leads to:
salmonella - sickle cell disease 
brucella - milk/travel
s.epidermis - prosthesis
H.influenzae - children under 5 
ecoli and others - UTI

Question 11

Haematogenous Spread to Bones

Answer 11

• Usually asymptomatic
• Skin sepsis may be present (but is usually
absent)
• Organisms settle in growing metaphysis near growth plate

Question 12

foreign bodies that can cause osteomyelitis

Answer 12

• Trauma
• Shrapnel/Gun shot wound
• Orthopaedic implant (K nail)
• Nail through trainer (Pseudomonas)

Question 13

Organisms responsible for osteomyelitis

Answer 13

• S. aureus (>80%)
• S. pyogenes (~5%)
• Gram negative bacteria • M. tuberculosis

Question 14

symptoms/sign of osteomyelitis

Answer 14

• Painful swollen site
• Fever
• Reduced movement (may be only sign in very young)
• Paraplegia

Question 15

preliminary investigations for osteomyelitis

Answer 15

• Fever
• WBC
• ESR
• CRP

Question 16

further investigations for osteomyelitis

Answer 16

Investigations
• Bloodculture
• X-ray
• MRI/CT/Bonescan 
• 
• Take 3 cultures (surgeons may take up to 6)
• May be negative early on in the course of infection
• Operative sample

Question 17

therapeutic regimes

Answer 17

• Alternatives empirical
- Ciprofloxacin (for Salmonella infection)
- Isoniazid, Rifampicin, Pyrazinamide, Ethambutol (tuberculosis)
• Drainage/Removal of involucrum