Skin and Soft Tissue Infections

Question 1

What are the names of the infection sites for each skin compartment?

Answer 1

Question 2

What are the organisms that cause skin infections, in each infection site?

Answer 2

• 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

Question 3

What are predisposing factors for impetigo?

Answer 3

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

* common 2-5 yrs

Question 4

What are the features of impetigo?

Answer 4

• multiple vasicular lesions on erythematous base
• golden crust
• highly infectious
• face, extremities, scalp

Question 5

What is the treatment for impetigo?

Answer 5

• small areas- topical antibiotics
• large areas- topical + oral antibiotics

Question 6

What are the predisposing factors for erysipelas?

Answer 6

• lymphoedema
• venous stasis
• obesity
• paraparesis
• diabetes

Question 7

What are the features of erysipelas?

Answer 7

• painful, red area (no central clearing)
• associated fever
• lymphadenopathy, lymphangitis
• distinct elevated borders
• lower limbs, face
• high recurrence rate (30%)

Question 8

What is the treatment for erysipelas?

Answer 8

• anti-staphlococcal + anti-streptococcal antibiotics
• IV antibiotics

Question 9

What are the predisposing factors for cellulitis?

Answer 9

• diabetes
• tinea pedis
• lymphoedema

Question 10

What are the features of cellulitis?

Answer 10

• spreading erythematous area, no distinct borders
• fever
• lymphadenopathy, lymphangitis
• possible source of bacteraemia

Question 11

What is the treatment for cellulitis?

Answer 11

• anti-staphlococcal + anti-streptococcal antibiotics
• IV antibiotics

Question 12

What are the features of folliculitis?

Answer 12

• circumsribed, pustular
• small red papules
• central area of purulence, may rupture and drain
• ≤ 5mm
• head, back, buttocks, extremities

Question 13

What is the treatment for folliculitis?

Answer 13

• no treatment
• topical antibiotics

Question 14

What are the risk factors for furunculosis?

Answer 14

• obesity
• diabetes
• atopic dermatitis
• chronic kidney disease
• corticosteroids

Question 15

What are the features of furunulosis?

Answer 15

• boils
• extends into dermis + subcutaneous tissue
• moist, hairy, friction prone areas- face, axilla, neck, buttocks
• may spontaneously drain purulent material

Question 16

What is the treatment for furunculosis?

Answer 16

• no treatment
• topical antibiotics
• oral antibiotics

Question 17

What are the features of carbuncles?

Answer 17

• involve multiple furuncles
• neck, posterior trunk, thigh
• multiseptated abscesses
• purulent material may be expressed from multiple sites

Question 18

What is the treatment for carbuncles?

Answer 18

• surgery
• IV antibiotics

Question 19

What are predisposing conditions for necrotising fasciitis?

Answer 19

• diabetes
• surgery
• trauma
• peripheral vascular disease
• skin popping

Question 20

What are the features of necrotising fasciitis?

Answer 20

• 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

Question 21

What is the treatment for necrotising fasciitis?

Answer 21

• surgical review
• imaging
• broad spectrum antibiotics
• flucloxacillin, gentamycin, clindamycin

Question 22

What are predisposing factors for pyomitis?

Answer 22

• diabetes
• HIV/immunocompromised
• IV drug use
• rheumatological diseases
• malignancy
• liver cirrhosis

Question 23

What are the features of pyomitis?

Answer 23

• 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

Question 24

What is the treatment for pyomitis?

Answer 24

• CT/MRI
• drainage with antibiotic cover

Question 25

What are predisposing factors for septic bursitis?

Answer 25

* rheumatoid arthritis * alcoholism * diabetes * IV drug abuse * immunosuppression * renal insufficiency

Question 26

What are features of septic busitis?

Answer 26

* peribursal cellulitis * swelling, warmth, pain on movement, fever * diagnosis from aspiration of fluid * staph aureus

Question 27

What are the features of infectious tenosynovitis?

Answer 27

* 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

Question 28

What is the treatment for infectious tenosynovitis?

Answer 28

* empirical antibiotics * hand surgeon

Question 29

What is the pathophysiology of toxin-mediated syndromes?

Answer 29

* pyrogenic endotoxins * superantigens * endothelial leakage, haemodynamic shock, multi-organ failure, death * staph aureus, strep pyogenes

Question 30

What are the features of staphylococcal toxic shock syndrome?

Answer 30

* fever * hypotension * diffuse macular rash * involves 3 of; liver, blood, renal, GI, CNS, muscular * TSST1 produced by isolate * develop antibody to toxin during convalescence

Question 31

what are the features of streptococcal toxic shock syndrome?

Answer 31

* streptococci in deep seated infections, erysipelas, necrotising fasciitis * 50% mortality rate

Question 32

What is the treatment for toxic shock syndrome?

Answer 32

* remove offending agent * IV fluid * inotropes * antibiotics * IV immunoglobulins

Question 33

What are the features of staphylococcal scaled skin syndrome?

Answer 33

* staph aureus produce exfoliative toxin A/B * widespread bullae, skin exfoliation * children

Question 34

What is the treatment for staphylococcal scalded skin syndrome?

Answer 34

* IV fluids * antimicrobials

Question 35

What are features of Panton-Valentine leucocidin toxin?

Answer 35

* gamma haemolysin * staph aureus * SSTI, haemorrhagic pneumonia * children, young adults * recurrent boils, difficult to treat

Question 36

What is the treatment for Panton-Valentine leucocidintoxin?

Answer 36

* antibiotics that dec. toxin production

Question 37

What are risk factors IV-catherter associated infections?

Answer 37

* continuous infusion \> 24 hrs * annula in situ \> 72 hrs * cannula in lower limb * neurological/neurosurgical problems

Question 38

What are the features of IV-catheter associated infections?

Answer 38

* nosocomial infection * local SST inflammation -\> cellulitis -\> necrotising fasciitis * associated bacteraemia * staph aureus (MRSA, MSSA) * endocarditis, osteomyelitis

Question 39

What is the treatment for IV-catheter associated infections?

Answer 39

* +ve blood culture * echocardiogram * remove cannula * express any pus from thrombophlebitis * antibiotics (14 days)

Question 40

What are the different classifications of surgical site infections?

Answer 40

* class I- clean wound * class II- clean-contaminated wound * class III- contaminated wound * class IV- infected wound

Question 41

What are different causes of surgical site infections?

Answer 41

* staph aureus (MSSA, MRSA) * coagulase negative staphylococci * enterococcus * e coli * pseudomonas aeruginosa * enterobacter * streptococci * fungi * anaerobes

Question 42

What are risk factors for surgical site infections?

Answer 42

* 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

Question 43

What is the treatment for surgical skin infections?

Answer 43

* pus/infected tissue cultures, swab deep structure * antibiotics