Skin and Soft Tissue Infections Flashcards
What are the names of the infection sites for each skin compartment?
What are the organisms that cause skin infections, in each infection site?
- impetigo- s aureus, strep pyogenes
- foliculitis- s aureus
- erysipelas- strep pyogenes
- cellulitis- strep pyogenes, s aureus, h influenzae, other
- necrotising fasciitis- strep pyogenes, mixed bowel flora
What are predisposing factors for impetigo?
- skin abrasions
- minor trauma
- burns
- poor hygiene
- insect bites
- chicken pox
- eczema
- atopic dermatitis
* common 2-5 yrs
What are the features of impetigo?
- multiple vasicular lesions on erythematous base
- golden crust
- highly infectious
- face, extremities, scalp
What is the treatment for impetigo?
- small areas- topical antibiotics
- large areas- topical + oral antibiotics
What are the predisposing factors for erysipelas?
- lymphoedema
- venous stasis
- obesity
- paraparesis
- diabetes
What are the features of erysipelas?
- painful, red area (no central clearing)
- associated fever
- lymphadenopathy, lymphangitis
- distinct elevated borders
- lower limbs, face
- high recurrence rate (30%)
What is the treatment for erysipelas?
- anti-staphlococcal + anti-streptococcal antibiotics
- IV antibiotics
What are the predisposing factors for cellulitis?
- diabetes
- tinea pedis
- lymphoedema
What are the features of cellulitis?
- spreading erythematous area, no distinct borders
- fever
- lymphadenopathy, lymphangitis
- possible source of bacteraemia
What is the treatment for cellulitis?
- anti-staphlococcal + anti-streptococcal antibiotics
- IV antibiotics
What are the features of folliculitis?
- circumsribed, pustular
- small red papules
- central area of purulence, may rupture and drain
- ≤ 5mm
- head, back, buttocks, extremities
What is the treatment for folliculitis?
- no treatment
- topical antibiotics
What are the risk factors for furunculosis?
- obesity
- diabetes
- atopic dermatitis
- chronic kidney disease
- corticosteroids
What are the features of furunulosis?
- boils
- extends into dermis + subcutaneous tissue
- moist, hairy, friction prone areas- face, axilla, neck, buttocks
- may spontaneously drain purulent material
What is the treatment for furunculosis?
- no treatment
- topical antibiotics
- oral antibiotics
What are the features of carbuncles?
- involve multiple furuncles
- neck, posterior trunk, thigh
- multiseptated abscesses
- purulent material may be expressed from multiple sites
What is the treatment for carbuncles?
- surgery
- IV antibiotics
What are predisposing conditions for necrotising fasciitis?
- diabetes
- surgery
- trauma
- peripheral vascular disease
- skin popping
What are the features of necrotising fasciitis?
- rapid onset
- erythema, extensive oedema, severe unremitting pain
- haemorrhagic bullae, skin necrosis, crepitus
- fever, hypotension, tachycardia, delirium, multi-organ failure
- anaesthesia at site of infection
* type I- mixed aerobic + anaerobic infection
type II- monomicrobial
What is the treatment for necrotising fasciitis?
- surgical review
- imaging
- broad spectrum antibiotics
- flucloxacillin, gentamycin, clindamycin
What are predisposing factors for pyomitis?
- diabetes
- HIV/immunocompromised
- IV drug use
- rheumatological diseases
- malignancy
- liver cirrhosis
What are the features of pyomitis?
- purulent, in deep striated muscle
- abscess
- thigh, calves, arms, gluteal region, chest wall, psoas muscle
- fever
- pain
- woody induration of affected muscle
- septic shock, death
What is the treatment for pyomitis?
- CT/MRI
- drainage with antibiotic cover
What are predisposing factors for septic bursitis?
- rheumatoid arthritis
- alcoholism
- diabetes
- IV drug abuse
- immunosuppression
- renal insufficiency
What are features of septic busitis?
- peribursal cellulitis
- swelling, warmth, pain on movement, fever
- diagnosis from aspiration of fluid
- staph aureus
What are the features of infectious tenosynovitis?
- synovial sheaths surrounding tendons
- flexor muscle tendons + hands
- erythematous fusiform finger swelling, held in semiflexed position, tenderness, pain on extension
- penetrating trauma
- staph aureus, streptococci
- chronic infection- mycobacteria, fungi
- disseminated gonococcal infection
What is the treatment for infectious tenosynovitis?
- empirical antibiotics
- hand surgeon
What is the pathophysiology of toxin-mediated syndromes?
- pyrogenic endotoxins
- superantigens
- endothelial leakage, haemodynamic shock, multi-organ failure, death
- staph aureus, strep pyogenes
What are the features of staphylococcal toxic shock syndrome?
- fever
- hypotension
- diffuse macular rash
- involves 3 of; liver, blood, renal, GI, CNS, muscular
- TSST1 produced by isolate
- develop antibody to toxin during convalescence
what are the features of streptococcal toxic shock syndrome?
- streptococci in deep seated infections, erysipelas, necrotising fasciitis
- 50% mortality rate
What is the treatment for toxic shock syndrome?
- remove offending agent
- IV fluid
- inotropes
- antibiotics
- IV immunoglobulins
What are the features of staphylococcal scaled skin syndrome?
- staph aureus produce exfoliative toxin A/B
- widespread bullae, skin exfoliation
- children
What is the treatment for staphylococcal scalded skin syndrome?
- IV fluids
- antimicrobials
What are features of Panton-Valentine leucocidin toxin?
- gamma haemolysin
- staph aureus
- SSTI, haemorrhagic pneumonia
- children, young adults
- recurrent boils, difficult to treat
What is the treatment for Panton-Valentine leucocidintoxin?
- antibiotics that dec. toxin production
What are risk factors IV-catherter associated infections?
- continuous infusion > 24 hrs
- annula in situ > 72 hrs
- cannula in lower limb
- neurological/neurosurgical problems
What are the features of IV-catheter associated infections?
- nosocomial infection
- local SST inflammation -> cellulitis -> necrotising fasciitis
- associated bacteraemia
- staph aureus (MRSA, MSSA)
- endocarditis, osteomyelitis
What is the treatment for IV-catheter associated infections?
- +ve blood culture
- echocardiogram
- remove cannula
- express any pus from thrombophlebitis
- antibiotics (14 days)
What are the different classifications of surgical site infections?
- class I- clean wound
- class II- clean-contaminated wound
- class III- contaminated wound
- class IV- infected wound
What are different causes of surgical site infections?
- staph aureus (MSSA, MRSA)
- coagulase negative staphylococci
- enterococcus
- e coli
- pseudomonas aeruginosa
- enterobacter
- streptococci
- fungi
- anaerobes
What are risk factors for surgical site infections?
- diabetes
- smoking
- obesity
- malnutrition
- concurrent steroid use
- colonisation with staph aureus
- shaving site night before procedure
- improper preoperative skin preparation
- improper antimicrobial prophylaxis
- break in sterile technique
- inadequate theatre ventilation
- perioperative hypoxia
What is the treatment for surgical skin infections?
- pus/infected tissue cultures, swab deep structure
- antibiotics
