necrotising fascitis Flashcards
what is necrotising fascitis
bacterial infection of the soft tissue and fascia
classification of necrotising fasciitis
Type I (polymicrobial i.e. more than one bacteria involved)
Type II (due to haemolytic group A streptococcus, staphylococci including methicillin-resistant strains/MRSA)
Type III (gas gangrene, eg due to clostridium)
Other: marine organisms
causes if necrotising fasciitis
- wound, surgery
- direct contact
risk factors for nectrosing fasciitis
- Aspirin and non-steroidal anti-inflammatory drugs
- Advanced age
- Diabetes
- Immune suppression
- Obesity
- Drug abuse
- Severe chronic illness
- Malignancy.
symptoms/signs of necrotising fasciitis
pain fever, N, diarrhoea swelling blisters with dark fluid oedema crackiling sensation unser the skin due to the gas
diagnosis of nectrotising fasciitis
A positive finger test is highly pathognomic for necrotising fasciitis. A 2–cm vertical incision is made in the affected skin and an index finger is pushed into the tissue. The test is positive if the finger passes through the subcutaneous tissue without resistance
There is poor adherence of tissue to the fascia on incising the site.
Necrotic tissue/pus oozes out of the fascial planes.
Dishwater-coloured fluid seeps out of the skin.
Typically, necrotising fasciitis does not bleed.
tool used in necrotising fasciitis
LRINEC
tX FOR NECROTISING FASCIITIS
hospitalised
IV ABx
The initial antibiotic choice includes penicillin, clindamycin, metronidazole, cephalosporins, carbapenems, vancomycin and linezolid. After the culture is reported, the choice is adjusted.
It is absolutely vital than an experienced surgeon urgently removes all necrotic tissue (debridement).
Supplemental oxygen, fluids and medicines may be needed to raise blood pressure.
Hyperbaric oxygen and intravenous immunoglobulin may also be considered.
complications of necrotising fasciitis
renal failure and septicaemia (blood poisoning) and multiorgan failure.
what is erythema multiforme
hypersensitivity reaction usually triggered by infections, most commonly herpes simplex virus (HSV). It presents with a skin eruption characterised by a typical target lesion.
who gets erythema multiforme
young adults
Triggers of erythema multiforme
infections - HSV
then mycoplasma pneumonia
Drugs - NSAIDS, penicillins
clinical features of erythema multiforme
first seen on the backs of hands and/or tops of feet and then spread down the limbs towards the trunk.
- may be associated with itch or burning sensation
- sharply demarcated, round red/pink and falt
- raised adn enlarge to form plaques
- centre of papule darken in colour adn devekops epidermal changes
- blistering or crusting
EVOLVE OVER 72 HOURS
how does a typical target lesion of erythema multiforme present
sharp margin, regular round shape and three concentric colour zones:
The centre is dusky or dark red with a blister or crust
Next ring is a paler pink and is raised due to oedema (fluid swelling)
The outermost ring is bright red.
Mx of erythema multifome
No mx is required as it settles by itself
Supportive/symptomatic treatment may be necessary.
Itch — oral antihistamines and/or topical corticosteroids may help.
Oral pain — mouthwashes containing local anaesthetic and antiseptic reduce pain and secondary infection.
Eye involvement should be assessed and treated by an ophthalmologist.
Erythema multiforme major may require hospital admission for supportive care, particularly if severe oral involvement restricts drinking.
