Gangrene + Necrotising Fascitis Flashcards
def of gangrene
tissue necrosis can be: -wet with superimposed infection -dry with desiccation -gas gangrene
what is desiccation
extreme dryness
cracking of skin
def of NF
a life threatening condition that spreads rapidly along fascial planes
what is fourniers gangrene
necrotising fascitis of the perineum
aetiology of gangrene
1 tissue ischaemia + infarction
2 trauma
3 thermal injury
aetiology of gas gangrene
clostridia perfringens
aetiology of NF
1 infection with group A streptococcus
2 polymicrobial infection with streptococci, staphylococci, bacteriodes
associations/risk factors
1 diabetes
2 peripheral vascular disease + leg ulcers
3 malignancy
4 immunosuppression
5 steroid use
6 NF can occur in relation to puncture wounds, surgical wounds
epi
gangrene - common
gas gangrene - uncommon
NF - uncommon
history of gangrene
1 pain
2 discolouration
3 often affects extremities or areas subject to pressure
history of NF
1 pain (severe) 2 history of factors or predisposing event
pathogenesis of gangrene
1 tissue damage + ischaemia predispose to bacteria
2 in an anaerobic environment, synergy between the organisms occurs perpetuating the cycle of tissue damage + bacterial growth
3 bacteria grow in anaerobic environment of damaged tissue + produce exotoxins
4 exotoxins destroy local microcirculation, cause necrosis, haemolysis + sepsis
what bacteria grow in an anaerobic environment in sepsis
clostridium perfringens
clostridium novyi
clostridium sepicum
what exotoxins destroy local microcirculation
a lethicinase
pathogenesis of NF
1 most commonly a synergistic polymicrobial infection spreading along fascial planes
2 often caused by group A beta-haemolytic streptococcus pyogenes
