skin and soft tissue infection Flashcards
what is impetigo ?
superficial skin infection
multiple vesicular lesions on erythematous base
golden crust highly suggestive
2-5 years, highly infectious
face, extremities, scalp
what causes impetigo ?
staph aureus
strep pyogenes
what are predisposing factors for impetigo ?
skin abrasions minor trauma burns poor hygiene insect bites chicken pox eczema atopic dermatitis
how do you treat impetigo ?
small area - topical antibiotics
large area - topical + oral flucloxacillin
what is erysipelas ?
infection of upper dermis
painful red area, elevated borders
associated fever, regional lymphadenopathy
commonly strep pyogenes
where does erysipelas affect ?
70-80% lower limb
tends to occur in areas of lymphodema, venous stasis, obesity, paraparesis, DM
high recurrence rate
what is cellulitis ?
diffuse skin infection involving deep dermis and subcutaneous fat
spreading erythematous area with no distinct border
fever, lymphadenopathy, can cause bacteraemia
what causes cellulitis ?
staph aureus
strep pyogenes
what are predisposing factors for cellulitis ?
DM
tinea pedis
lymphodema
how do you treat cellulitis and erysipelas ?
combo of anti-staph, anti-strep antibiotics
IV antibiotics if extensive
what is folliculitis ?
circumscribed, pustular infection of hair follicle
up to 5mm in diameter
can spontaneously drain
head, back, buttocks, extremities
what organism causes folliculitis ?
staph aureus
what is furunculosis ?
boils
single follicle inflammatory nodule extending into dermis and subcutaneous tissue
usually moist, hairy, friction-prone areas of body
spontaneously drain purulent material
staph aureus
what are risk factors for furunculosis ?
obesity DM atopic dermatitis chronic kidney disease corticosteroid use
what is a carbuncle ?
infection involves multiple furuncles
located on back or thigh
purulent material from multiple sites
constitutional symptoms common
how do you treat hair-associated infections ?
folliculitis - no treatment/topical antibiotics
furunculosis - no treat, topical/oral antibiotics
carbuncles - admission, iv antibiotics, surgery
what are risk factors for necrotising fasciitis ?
DM surgery trauma peripheral vascular disease skin popping
what is type 1 necrotising fasciitis ?
mixed aerobic and anaerobic infection - diabetic foot
typically strep, staph, enterococci, gram -ve, clsotridium
what is type 2 necrotising fasciitis ?
mono microbial
normally strep pyogenes
what are clinical features of necrotising fasciitis ?
rapid onset
erythema, extensive oedema, unremitting pain
haemorrhage bull, skin necrosis, crepitus
system - fever, hypotension, tachycardia, delirium, multiorgan failure
anaesthesia at site of infection if highly suggestive of disease
how do you treat necrotising fasciitis ?
surgical review
broad spectrum antibiotics - flucloxacillin, gentamicin, clindamycin
what is pyomyositis ?
purulent deep infection in striated muscle, manifest as abscess
infection often secondary to damaged muscle
commonly limbs, chest, psoas
staph aureus, +ve/-ve, TB, fungi
how does pyomyositis present ?
fever
pain
woody induration of muscle
can lead to septic shock and death
what are risk factors for pyomyositis ?
DM HIV/ immunocompromised IV drug use rheumatological disease malignancy liver cirrhosis
how do you manage pyomyositis ?
CT/MRI
drainage
antibiotic cover
what are toxin-mediated syndromes ?
due to superantigens, pyrogenic exotoxins
attach directly to Cell receptors activating huge amounts of T cells, massive cytokine release
leads to endothelial leakage, haemodynamic shock, multi-organ failure
what causes toxin-mediated syndromes ?
staph aureus - TSST, ETA, ETB
strep pyogenes - TSST
what is diagnostic criteria for staph TSS ?
fever
hypotension
diffuse macular rash
three of liver, blood, renal, GI, CNS, muscular involved
isolation of staph aureus from mucosal or sterile site
production of TSST
development of Ab to toxin during convalescence
what is different about strep TSS ?
associated
what does panton-valentine toxin do ?
staph aureus
recurrent boils
haemorrhagic pneumonia and SSTI
what are risk factors of IV catheter associated infections ?
continuous infusion >24 hours
cannula in situ >72 hours
cannula in lower limb
patients with neurological problems
how do you treat iv catheter infection ?
remove cannula
get rid of pus
antibiotics for 14 days
ECHO
what are the different classes of surgical wound ?
class 1 - clean wound, systems not entered class 2 - clean-contaminated wound, tracts entered but no contamination class 3 - contaminated wound, class 4 - infected wound
what are patient associated risk factors for surgical infections ?
diabetes smoking obesity malnutrition concurrent steroid use colonisation with staph aureus
what are procedural associated risk factors for surgical site infections ?
shaving of site the night before improper preoperative skin preparation improper antimicrobial prophylaxis break in sterile technique inadequate theatre ventilation preoperative hypoxia
