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Flashcards in Infections Deck (14):
1

What is meant by necrotising fasciitis?

How does it present?

Life-threatening infection that spreads along the soft tissue planes commonly caused by clostridia, group B strep
Risk factors: IVDU, DM, surgery, bites and cuts
Presents with localised abscess/cellulitis with repaid spreads, severe pain, fever, rigours ,tachycardia
O/E skin bullae, ischaemic patches, cutaneous gangrene, subcutaneous emphysema

2

What is the management of necrotising fasciitis?

A to E with would swabs
Biopsy and LRINEC score can be used in early cases
Emergency radical debridement with broad spectrum IV Abx (Pen, Clin, Met and aminoglycoside)
Hyperbaric oxygen chamber to eliminate anaerobic MO
Consider amputation

3

What are the different types of necrotising fasciitis?

Type 1 - polymicrobial - most common
Type 2 - monomicrobial - Group A strep
Type 3 - marine vibrio vulnificus (gram negative rods)
Type 4 - MRSA

4

What are the risk factors for osteomyelitis?

IVDU, diabetes, renal failure, sickle cell disease

5

What is the basic pathophysiology of osteomyelitis?

Infection of the bone
In children, this is usually due to haematogenous spread. The micro-organisms lodge where the blood flow is slowest (metaphysis). This can lead to a secondary septic arthritis

In adults and children, there can also be spread of MO from the skin to the bone in open fracture etc

6

What are the common organisms implicated in osteomyelitis?

Most common organism is Staph A (adults and children)
Group B strep is the most common organism in neonates
Salmonella is pathognomonic in sickle cell disease

7

How does osteomyelitis present clinically?

What are the appropriate investigations?

Painful, red, swollen joint, reduced range of movement, ongoing pain following trauma or fracture, unable to weight bear/limp

WBC, ESR, CRP
Joint aspirate
AP and lateral X-Rays - consider CT/MRI

8

What is meant by sequestrum?

In osteomyelitis, it is an area of necrotic bone which has been walled off from its blood supply

9

What is meant by involucrum?

In osteomyelitis, it is a new layer of bone growth outside existing bone, e.g. Around sequestrum

10

What are the management options in osteomyelitis?

Bone biopsy is gold standard for guiding antibiotic therapy IV/PO for 4-6/52
If no response, abscess formation, draining sinus - irrigation, debridement and organism sensitive antibiotics - any non-essential hardware should be removed

11

What are the possible complications of osteomyelitis?

Persistence/extension of infection
Sepsis
Amputation
Marjolin's ulcer

12

What is meant by a Marjolin's ulcer?

A malignant tumour that develops around chronic osteomyelitis/burn scars/venous ulcers/traumatic wounds
Most commonly squamous cell carcinoma
Usually involving the lower extremities
More commonly occurring at the edges of the wound where there is high cell turnover

13

When should a Marjolin's ulcer be suspected?

Suggested by increasing wound size or foul smelling
Consider in patients with a long standing wound or scar that has undergone recent change and is refractory to wound care
Be suspicious if a wound isn't healing after 3 months of appropriate wound care

14

How should a suspected Marjolin's ulcer be investigated?

What are the management options?

Histological analysis
Treatment of choice in most cases is wide local excision with skin grafting