skin and soft tissue infection

Question 1

what is impetigo ?

Answer 1

superficial skin infection
multiple vesicular lesions on erythematous base
golden crust highly suggestive

2-5 years, highly infectious
face, extremities, scalp

Question 2

what causes impetigo ?

Answer 2

staph aureus

strep pyogenes

Question 3

what are predisposing factors for impetigo ?

Answer 3

skin abrasions
minor trauma
burns
poor hygiene
insect bites
chicken pox
eczema
atopic dermatitis

Question 4

how do you treat impetigo ?

Answer 4

small area - topical antibiotics

large area - topical + oral flucloxacillin

Question 5

what is erysipelas ?

Answer 5

infection of upper dermis
painful red area, elevated borders
associated fever, regional lymphadenopathy

commonly strep pyogenes

Question 6

where does erysipelas affect ?

Answer 6

70-80% lower limb

tends to occur in areas of lymphodema, venous stasis, obesity, paraparesis, DM
high recurrence rate

Question 7

what is cellulitis ?

Answer 7

diffuse skin infection involving deep dermis and subcutaneous fat

spreading erythematous area with no distinct border
fever, lymphadenopathy, can cause bacteraemia

Question 8

what causes cellulitis ?

Answer 8

staph aureus

strep pyogenes

Question 9

what are predisposing factors for cellulitis ?

Answer 9

DM
tinea pedis
lymphodema

Question 10

how do you treat cellulitis and erysipelas ?

Answer 10

combo of anti-staph, anti-strep antibiotics

IV antibiotics if extensive

Question 11

what is folliculitis ?

Answer 11

circumscribed, pustular infection of hair follicle
up to 5mm in diameter
can spontaneously drain
head, back, buttocks, extremities

Question 12

what organism causes folliculitis ?

Answer 12

staph aureus

Question 13

what is furunculosis ?

Answer 13

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

Question 14

what are risk factors for furunculosis ?

Answer 14

obesity
DM
atopic dermatitis
chronic kidney disease
corticosteroid use

Question 15

what is a carbuncle ?

Answer 15

infection involves multiple furuncles
located on back or thigh
purulent material from multiple sites
constitutional symptoms common

Question 16

how do you treat hair-associated infections ?

Answer 16

folliculitis - no treatment/topical antibiotics
furunculosis - no treat, topical/oral antibiotics
carbuncles - admission, iv antibiotics, surgery

Question 17

what are risk factors for necrotising fasciitis ?

Answer 17

DM
surgery
trauma
peripheral vascular disease
skin popping

Question 18

what is type 1 necrotising fasciitis ?

Answer 18

mixed aerobic and anaerobic infection - diabetic foot

typically strep, staph, enterococci, gram -ve, clsotridium

Question 19

what is type 2 necrotising fasciitis ?

Answer 19

mono microbial

normally strep pyogenes

Question 20

what are clinical features of necrotising fasciitis ?

Answer 20

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

Question 21

how do you treat necrotising fasciitis ?

Answer 21

surgical review

broad spectrum antibiotics - flucloxacillin, gentamicin, clindamycin

Question 22

what is pyomyositis ?

Answer 22

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

Question 23

how does pyomyositis present ?

Answer 23

fever
pain
woody induration of muscle

can lead to septic shock and death

Question 24

what are risk factors for pyomyositis ?

Answer 24

DM
HIV/ immunocompromised
IV drug use
rheumatological disease
malignancy
liver cirrhosis

Question 25

how do you manage pyomyositis ?

Answer 25

CT/MRI
drainage
antibiotic cover

Question 26

what are toxin-mediated syndromes ?

Answer 26

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

Question 27

what causes toxin-mediated syndromes ?

Answer 27

staph aureus - TSST, ETA, ETB

strep pyogenes - TSST

Question 28

what is diagnostic criteria for staph TSS ?

Answer 28

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

Question 29

what is different about strep TSS ?

Answer 29

associated

Question 30

what does panton-valentine toxin do ?

Answer 30

staph aureus
recurrent boils
haemorrhagic pneumonia and SSTI

Question 31

what are risk factors of IV catheter associated infections ?

Answer 31

continuous infusion >24 hours
cannula in situ >72 hours
cannula in lower limb
patients with neurological problems

Question 32

how do you treat iv catheter infection ?

Answer 32

remove cannula
get rid of pus
antibiotics for 14 days
ECHO

Question 33

what are the different classes of surgical wound ?

Answer 33

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

Question 34

what are patient associated risk factors for surgical infections ?

Answer 34

diabetes
smoking
obesity
malnutrition
concurrent steroid use
colonisation with staph aureus

Question 35

what are procedural associated risk factors for surgical site infections ?

Answer 35

shaving of site the night before
improper preoperative skin preparation
improper antimicrobial prophylaxis
break in sterile technique
inadequate theatre ventilation
preoperative hypoxia