Abscess Flashcards
def
collection of pus surrounded by a wall of tissue
aetiology
tissue barrier is disrupted by injury, infection, migration of normal flora to sterile areas of the body
this areas becomes walled off to encapsulate and limit further spread of infection
what are the common bacteria involved in abscesses
staph
strep
e. coli
what causes cold abscesses
TB
what is associated with local abscesses
tissue necrosis - an underperfused space of which provides a focus for infection
what is associated with systemic abscesses
diabetes
immunosuppresion
history
abscess may be red, hot swollen and painful
additionally there may be signs of systemic infection such as fever or malaise
examination
signs of acute inflammation at site of abscess (if superficial)
if abscess is present within an organ only fever may be observable
what sort of fever is associated with abscesses
swinging fever
what causes the swinging fever in abscesses
periodic release of microbes or inflammatory mediators into the systemic circulation
pathogenesis
bacteria induce an acute inflammatory response and the formation of pus
an abscess forms as it becomes surrounded by a fibrinous exudate and granulation tissue with subsequent collagen deposition which walls off the infection
what is pus
collection of cellular debris and bacteria
what is granulation tissue formed of
macrophages and fibroblasts
what are cold abscesses
caused by TB
caseating necrosis
they are ‘cold’ because there is no associated inflammatory response
investigations
1 bloods -FBC with raised WCC 2 imaging -USS, CT, MRI to search for abscesses 3 aspiration -C+S of pathogens
