Osteomyelitis & Septic Arthritis Flashcards
What is osteomyelitis?
Inflammation in a bone or bone marrow, usually caused by bacterial infection.
Define haematogenous osteomyelitis
When a pathogen is carried through the blood and seeded in the bone (i.e. remote source of infection e.g. cannula, IVDU)
What is the most common mode of infection in osteomyelitis?
Haematogenous osteomyelitis
What is nonhaematogenous osteomyelitis associated with?
Direct inoculation via trauma or medical procedures
What pathogen causes most cases of osteomyelitis?
Staph. aureus
Give 3 conditions associated with osteomyelitis
1) Diabetes
2) Peripheral arterial disease
3) Sickle cell disease
How can diabetes lead to osteomyelitis?
Poorly controlled diabetes with associated peripheral neuropathy:
1) impairs blood supply
2) this can lead to the development of non-healing infected ulcers and 2ary nonhaematogenous spread of the associated pathogens to bone
How can PAD lead to osteomyelitis?
Through a similar process to diabetes
How can sickle cell disease lead to osteomyelitis?
Sickle cell can cause infarction of the bone and bone marrow leading to secondary infection
What are the key risk factors for developing osteomyelitis?
1) Open fractures
2) Orthopaedic operations, particularly with prosthetic joints
3) Diabetes, particularly with diabetic foot ulcers
4) Peripheral arterial disease
5) IV drug use
6) Immunosuppression
Infection in a prosthetic joint is a big problem.
When is this more likely to occur?
In revision surgery rather than during the initial joint replacement.
What can be done to reduce the risk of infection in prosthetic joints?
Perioperative prophylactic antibiotics
Osteomyelitis can be acute or chronic.
What are the features of acute osteomyelitis?
- Pain
- Warmth
- Erythema
- Swelling of the soft tissue surrounding the affected bone
- Systemic e.g. fever, malaise
What is the imaging of choice in suspected osteomyelitis?
MRI
What investigations can be done in suspected osteomyelitis?
1) MRI scan
2) Bloods: WBC, CRP, ESR
3) Blood cultures
Mx of osteomyelitis?
1) Abx
2) +/- surgical debridement
1st line Abx in osteomyelitis?
6 weeks of flucloxacillin, possibly with rifampicin or fusidic acid added for the first 2 weeks
If MRSA is suspected in osteomyelitis, what Abx should be given?
Vancomycin or teicoplanin
How long is abx treatment in acute osteomyelitis?
6 weeks
What can be used as an alternative to flucloxacillin in the mx of osteomyleitis in a penicillin allergy?
Clindamycin
How long is abx treatment in chronic osteomyelitis?
Chronic osteomyelitis usually requires 3 months or more of antibiotics.
