Bone & Soft TIssue Infections Flashcards
This deck covers:
Acute & Chronic Osteomyelitis
Septic Arthritis
TB
Who suffers from osteomyelitis?
Mostly kids, and generally boys with a trauma history
What are the common sources of OM infection?
Haematogenous - kids & elderly
Local spread from trauma & surgery
UTIs & arterial lines in adults
2* to vascular insufficiency
Infected Umbilical Cord in infants
Soft tissue infection
What organism is the mian cause of OM
1) Staph Aureus
It’s the biggest cause in any patient group. However certain groups (e.g. by age, co-morbidity or immunocompromise) are at risk of other specific organisms
What organisms cause OM in infants <1yr?
1) Staph Aureus
2) Group B Strep
3) E. Coli (most common if under <1month old)
What organisms cause OM in diabetics?
Staph Aureus
Mixed infection incl. Anaerobes
What organisms cause OM in Sickle Cell patients?
Staph Aureus
Salmonella
What organisms cause OM in HIV/AIDS patients?
Staph Aureus
Candida
Where in the bone is OM likely to arise?
The metaphysis of long bones or joints with an intra-articular metaphysis e.g. hip/elbow (this can lead to septic arthritis or arise from SA)
Describe the pathogenesis of OM?
Acute inflammation
- > Increase Pressure
- > Suppuration
- > Pressure released into joint
- > Necrosis of bone
- > New Bone growth
- > REsolves or Chronic
What do we call necrosed bone?
Sequestrum
What do we call new bone growth?
Involucrum
How might OM present in an infant?
Failure to thrive ~drowsy or irritable Decreased movement or an odd position Tenderness & swelling over metaphysis Mostly in the knee
How might OM present in a child?
Severe pain +/- tenderness, fever and tachycardia
Systemic Symptoms e.g. fatigue, malaise & N&V
They won’t move or weight bear on that bone
How might primary OM present in an Adult?
MOstly in the thoracolumbar spine
So backache with a h/o UTI or urological procedure
Esp. in the elderly, diabetic or immunocompromised
How might secondary OM present in an adult?
Post an open fracture or surgery
What tests could we do to diagnose OM?
FBC Differential WCC U&Es 3x Blood cultures MRI X-ray Bone biopsy ESR & CRP
Also Aspiration, US, ISotope bone scan and labelled WC scan
And swabs from site during implantation surgery
What would appear on an acute OM Diff. WCC?
Neutrophilic Leucocytosis
What would appear on an Acute OM X-ray?
nothing in first 2 wks
10-20 days you get Early periosteal changes
Then you get late bone necrosis (Sequestrum) and LAte periosteal growth (Involucrum)
DDX for Acute OM?
Acute Septic Arthrits (more common)
Acute Inflammatory Arthritis
Trauma
Transient Synovitis
Soft Tissue Infection (e.g. erysipelas or Cellulitis)
Rarely sickle cell, rheumatic fever, necrotising fasciitis or Gaucher’s Disease
Treatment for Acute OM?
Supportive Care
Rest & Splintage
Abx
Surgery
Whats included in supportive care for acute OM?
Fluids
Analgesia
What Abx are used for Acute OM?
Empircally Flucloxacillin & Benzylpenicillin
4-6 wks on an IV/oral switch at 7-10 days
When would we perform surgery for Acute OM?
Refractory to Abx after 48 hours
Debride dead/infected tissue
Drain abscess
Aspirate abscess for culture
