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 [3]
Haematogenous:
- Infected Umbilical Cord in infants
- Boils/tonsilitis/skin abrasions in kids
- UTIs & arterial lines in adults
Local: open #
2* to vascular insufficiency
What organisms cause OM in infants <1yr? [3]
1) Staph Aureus
2) Group B Strep
3) E. Coli (most common if under <1month old)
What organisms cause OM in Older kids? [3]
1) Staph Aureus
2) Strep Pyogenes
3) H. Influenzae
What organisms cause OM in Adults? [4]
1) Staph Aureus
2) Coagulase -ve Staph via prosthesis
3) Mycobacterium TB
4) Pseudomonas Aeruginosa via penetrating foot injury or IVDA
What organisms cause OM in diabetics?
Pseudomonas
What organisms cause OM in Sickle Cell patients?
Salmonella
What organisms cause OM in people with dead fish contact? (Fishermen and filleters)
Mycobacterium Marinum
What organisms cause OM in HIV/AIDS patients?
Candida
Where in the bone is OM likely to arise? [2]
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 [5]
- venous congestion and venous thrombosis
- active inflammation and increased pressure results in…
- Suppuration which releases pressure and pus into medulla/joint
- Sequestrum is bone necrosis
- Involcrum - bone formation replaces necrosis with
- either resolution or chronic OM
How might OM present in an infant? [5]
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? [4]
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? [3]
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 open fracture or surgery
What tests could we do to diagnose OM? [8]
Indicate gold standard with *
Lab work Bone biopsy Tissue swabs Imaging USS Aspiration Isotope bone scan MRI*
What would appear on an acute OM Diff. WCC?
Describe how blood cultures should be done in acute OM?
In prosthetic infections, how many tissue swabs must be done around implant at debridement?
Neutrophilic Leucocytosis
Blood cultures should be done at pyrexial peak as the most bugs are released into circulation at this point
3 must be done
Prostethic infections: Max 5 sites
What would appear on an Acute OM X-ray? [4]
Early radiographs of acute OM will show minimal changes. What range of dates is this?
Periosteal changes
Medullary changes with lytic areas
Late osteonecrosis
Periosteal new bone - involucrum
10-14days
DDX for Acute OM? [5]
Rare causes [4]
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? [4]
Supportive Care
Rest & Splintage
Abx
Surgery
Whats included in supportive care for acute OM? [2]
Fluids
Analgesia
What Abx are used for Acute OM? [3]
What antibiotic to use for pseudomonas?
6w abx total
Empirical IV FLUCLOXICILLIN then switch to oral after 7-10d (ESR should return to normal in 4-6w)
Pseudomonas: CIPROFLOXACIN
When would we perform surgery for Acute OM? [4]
Refractory to Abx after 48 hours
Debride dead/infected tissue
Drain abscess
Aspirate abscess for culture
