Skin and soft tissue infection Flashcards
What layer of the skin does impetigo affect?
epidermis
Causative organisms of impetigo
staph aureus
strep pyogenes
List some predisposing factors for impetigo
break in skin
- burns
- poor hygiene
- minor trauma
- eczema
- chicken pox
- insect bites
Treatment for small areas of impetigo
topical antibiotics
Treatment for large areas of impetigo
topical and oral antibiotics
Area which erysipelas affects and causative organism
upper dermis
strep pyogenes
Describe appearance of impetigo
golden crust with multiple vascular lesions on erythematous base on the face or arms of children
describe appearance of erysipelas
painful red area with distinct elevated borders
Systemic symptoms of erysipelas
fever, lymphadenopathy and lymphangitis
Where on the body does erysipelas occur
70-80% lower limb and rest is face
4 predisposing factors for erysipelas
DM
venous stasis
obesity
pre-existing lymphoedema
Area of skin cellulitis affects
deep dermis and subcutaneous fat
Causative organisms of cellulitis
staph aureus and strep pyogenes
Describe the appearance of cellulitis
spreading erythematous area with no borders
systemic symptoms of cellulitis
fever, lymphadenopathy and lymphangitis
What 2 groups of patients may a gram -ve bacteria be causing cellulitis?
diabetics and febrile neutropenics
3 disposing factors for cellulitis
lymphoedema
tinea pedis
DM
Treating erysipelas and cellulitis
anti staph and anti strep antibiotics
if severe IV antibiotics and rest
10-14 days
3 hair associated infection
folliculitis
furunculosis
carbuncles
Describe folliculitis briefly
1 hair follicle affected
less than 5mm pustule with small red papules
Where is folliculitis found?
head, back, buttocks, extremities
Causative organism of folliculitis
staph aureus
Briefly describe furunculosis
single hair follicle associated with inflammatory nodule extending to dermis and subcutaneous fat
Where is furinculosis found?
moist, hairy, friction prone areas eg buttocks, neck, face
Causative organisms of furinculosis and risk factors
DM, obesity, CKD, CCS
Describe a carbuncle
infection involves multiple furuncles
where are carbuncles found?
back of neck, posterior trunk or thigh
treatment for
a) folliculitis
b) furunculosis
c) carbuncle
a - none or topical antibiotics
b) no treatment or topical/oral antibiotics
c) hospital, surgery, IV antibiotics
type 1 necrotising fasciitis (causative organisms)
mixed aerobic and anaerobic infection - diabetic foot
strep/staph, enterococci, Gram -ve bacilli
Type 2 necrotising fasciitis (causative organisms)
monomicrobial
strep pyogenes
Describe appearance of necrotising fasciitis
rapid onset or erythema –> extensive oedema and pain
haemorrhagic bullae, skin necrosis
anaesthesia at site
systemic symptoms of necrotising fasciitis
fever, hypotension, tachycardia, delirium, multi organ failure
treatment of necrotising fasciitis
surgery and imaging
broad spectrum antibiotics eg flucloxacillin
What is pyomyositis?
purulent infection deep within striated muscle secondary to seeding into damaged muscle
Predisposing factors of pyomyositis
HIV, IVDU, malignancy, DM, liver cirrhosis, rheumatological
pyomyositis causative organism
staph aureus
Treatment of pyomyositis
do a CT/MRI
drain! antibiotics
bursae
small sac like cavities that contain fluid and are lined by synovial membrane
Where does infection in septic bursitis usually spread from?
adjacent skin infection
predisposing factors of septic bursitis
RA, alcoholism, DM, IVDU, renal insufficiency
Common signs of septic bursitis
peribursal cellulitis, warmth and swelling
fever and pain
diagnosing septic bursitis
aspiration of fluid
Causative organisms of septic bursitis
staph aureus
What is infectious tenosynovitis?
infection of synovial sheaths surrounding tendons
Common sites of infectious tenosynovitis
flexor muscle tendons and tendon sheaths of hand
Causative organisms of infectious tenosynovitis
staph aureus and strep
Chronic infectious tenosynovitis causative organisms
mycobacteria and fungi (? gonococcal)
How infectious tenosynovitis presents
erythematous swelling of finger in semi flexed position
tenderness and pain with extension
Treatment of infectious tenosynovitis
empiric antibiotics and hand surgeon
What are toxin mediated syndromes often due to?
super antigens
Staph aureus toxins
TSST1 and ETA+ETB
strep pyogenes toxin
TSST1
What causes toxic shock syndrome?
staph aureus and TSST1
3 symptoms and signs of TSS
fever
hypotension
diffuse macular rash
4 diagnostic criteria for TSS
3 of following organs: liver,blood, renal, GI, CNS, muscle
isolation of staph aureus from mucosal or normally sterile site
TSST1 produced by isolate
development of antibody to toxin
Treatment of TSS
remove offending agent IV fluids IV immunoglobulins antibiotics inotropes
cause of SSSS
staph aureus toxin –> Exfoliative toxin A or B
SSSS presentation
widespread bullae and skin exfoliation in adults
treatment of SSSS
IV fluids and antimicrobials
Is panton valentine leucocidin toxin an alpha haemolysin?
no - beta
what can panton valentine leucocidin toxin cause?
skin and soft tissue infections and haemorrhagic pneumonia
treatment of panton valentine leucocidin toxin
antibiotics reducing toxin production
risk factors for IV associated catheter infections
continuous infusion >24 hours
cannula in situ >72 hours
cannula lower limb
neurological problems
causative organism of IV catheter associated infections
staph aureus
What can staph aureus in IV catheter associated infections lead to?
forms biofilm which spills into blood
seeds into other places
treating IV catheter associated infections
remove cannula
express pus from thrombophlebitis
IV antibiotics for 14 days
echo
5 ways to prevent IV catheter associated infections
do not leave unused cannula only insert cannula if using change every 72 hours monitor for thrombophlebitis use aseptic technique when inserting
class 1 surgical wound
clean - resp, GI, genital or infected urinary systems not entered
class 2 surgical wound
clean contaminated wound
class 3 surgical wound
open, fresh, accidental wounds
class 4 surgical wound
infected wound
list some causative organisms of IV catheter associated infections
staph aureus coagulase -ve staph enterococcus E coli pseudomonas aeruginosa Enterobacter streptococci fungi anaerobes
6 patient risk factors for IV catheter associated infections
diabetes malnutrition obesity smoking staph aureus colonisation concurrent steroid use
6 procedure risk factors for IV catheter associated infections
perioperative hypoxia improper antimicrobial prophylaxis shaving site the night prior to procedure break in sterile technique improper preoperative skin prep inadequate theatre ventilation
Diagnosing IV catheter associated infections and for especially what class of wound?
pus/infected tissue for cultures
clean wound infections
