Lecture 13 Skin and Soft Tissue Infections

Question 1

What are clinical features of Impetigo

Answer 1

Golden crust lesion

Question 2

What organisms commonly cause Impetigo

Answer 2

Staph aureus

Less commonly Strep Pyogenes

Question 3

What age group os common affected by impetigo

Answer 3

2-5 years

Question 4

What are predisposing factors of impetigo

Answer 4

o	Skin abrasions
o	Minor trauma
o	Burns
o	Poor hygiene
o	Insect bites
o	Chickenpox
o	Eczema
o	Atopic dermatitis

Question 5

How is impetigo treated

Answer 5

Topical antibiotics (small areas)
Oral antibiotics (Flucloxacillin)

Question 6

What is Erysipelas

Answer 6

Infection of the upper dermis

Question 7

What are the clinical features of Erysipelas

Answer 7

Painful red area
Fever
Regional Lymphadenopathy and lymphangitis
Lower limbs

Question 8

What organism is commonly associated with Erysipelas

Answer 8

Strep pyogenes

Question 9

What pre-existing conditions increase the risk of Erysipelas

Answer 9

pre-existing lymphoedema, venous stasis, obesity, paraparesis, diabetes mellitus

Question 10

What is cellulitis

Answer 10

Diffuse skin infection involving deep dermis and subcutaneous fat

Question 11

What is the clinical presentation of cellulitis

Answer 11

Spreading erythematous with no distinct border
Fever
Regional lymphadenopathy and lymphangitis

Question 12

What are the most likely causes of Cellulitis

Answer 12

Strep pyogenes
Staph aureus
Diabetes
Febrile neutropeanics

Question 13

What are predisposing factors of Cellulitis

Answer 13

DM
Tinea pedis
Lymphoedema

Question 14

How is Erysipelas and Cellulitis treated

Answer 14

Combination of anti-staphylococcal and anti-streptococcal antibiotics
In extensive disease, admission for intravenous antibiotics and rest

Question 15

What is folliculitis

Answer 15

o Circumscribed, pustular infection of a hair follicle

o Up to 5mm in diameter

Question 16

What are the clinical features of folliculitis

Answer 16

o Present as small red papules
o Central area of purulence that may rupture and drain
o Typically found on head, back, buttocks and extremities

Question 17

What is the common causative agent of folliculitis

Answer 17

Staph aureus

Question 18

What is Furunculosis

Answer 18

Boils

Single hair follicle-associated inflammatory nodule

Question 19

What areas to Furunculosis occur

Answer 19

Usually affected moist, hairy, friction-prone areas of body (face, axilla, neck, buttocks)

Question 20

What is a carbuncle

Answer 20

Occurs when infection extends to involve multiple furuncles

Question 21

Where are the common locations of carbuncles

Answer 21

neck, posterior trunk, or thigh

Question 22

How are hair-associated infections treated

Answer 22

Folliculitis- no treatment or topical antibiotics
Furunculosis- no treatment or topical antibiotics
Carbuncles- often require hospital admission, surgery and IV antibiotics

Question 23

What is type 1 Necrotising fasciitis

Answer 23

Mixed aerobic and anaerobic infection (diabetic foot infection, Fornier’s gangrene)

Question 24

Typical organisms that cause type 1 necrotising fasciitis

Answer 24

o	Streptococci
o	Staphylococci
o	Enterococci
o	Gram negative bacilli
o	Clostridium

Question 25

What is type 2 necrotising fasciitis

Answer 25

Mono-microbial | Normally associated with strep pyogenes

Question 26

What are the clinical features of necrotising fasciitis

Answer 26

``` Erythema extensive oedema haemorrhagic bullae Skin necrosis and crepitus Fever Hypotension tachycardia Delirium Multi-organ failure ```

Question 27

How is necrotising fasciitis treated

Answer 27

Antibiotics should be broad spectrum o Flucloxacillin o Gentamicin o Clindamycin

Question 28

What is pyomyositis

Answer 28

Purulent infection deep within striated muscle, often manifesting as an abscess Secondary to damaged muscle

Question 29

Common sites of Pyomyositis

Answer 29

``` o Thigh o Calf o Arms o Gluteal region o Chest wall ```

Question 30

What are the clinical features of pyomyositis

Answer 30

fever, pain and woody induration of affected muscle | If untreated can lead to septic shock and death

Question 31

What is the common causative organism of pyomyositis

Answer 31

Staph aureus

Question 32

How is pyomyositis diagnosed

Answer 32

CT/MRI

Question 33

How is Pyomyositis treated

Answer 33

Drainage with antibiotic cover depending on gram stain and culture

Question 34

What is septic bursitis

Answer 34

Infection of bursae -small sac-like cavities that contain fluid and are lined by synovial membrane Located subcutaneously between bony prominences or tendons

Question 35

Predisposing factors of septic bursitis

Answer 35

``` o Alcoholism o RA o DM o IV drug abuse o Immunosuppression o Renal insufficiency ```

Question 36

What are clinical features of septic bursitis

Answer 36

fever and pain in movement

Question 37

How is septic bursitis diagnosed

Answer 37

Aspiration of fluid | Staph aureus

Question 38

What is infectious tenosynovitis

Answer 38

Infection of the synovial sheaths that surround tendons

Question 39

What are the common causes of infectious tenosynovitis

Answer 39

Staph aureus and streptococci | Penetrating trauma

Question 40

What are the clinical features of infectious tenosynovitis

Answer 40

* Tenderness over the length of the tendon sheath and pain with extension of finger are classical * Present with erythematous fusiform swelling of finger

Question 41

How is infectious tenosynovitis treated

Answer 41

Empiric antibiotics, hand surgeon to review ASAP

Question 42

What are the causative agents of Toxin-mediated syndromes

Answer 42

Staph aureus- TSST1, ETA and ETB | Strep pyogenes- TSST1

Question 43

What are the diagnostic criteria for staphylococcal TSS

Answer 43

``` • Fever • Hypotension • Diffuse macular rash • Three of the following organs involved o Liver o Blood o Renal o GI o CNS o Muscular ```

Question 44

How is TSS treated

Answer 44

* Remove offending agent (ex-tampon) * IV fluids * Inotropes * Antibiotics * IV immunoglobulins

Question 45

What is Staphylococcal scalded skin syndrome

Answer 45

• Infection due to a particular strain of Staph aureus producing the exfoliate toxin A or B

Question 46

What are the clinical features of staphylococcal scalded skin syndrome

Answer 46

Widespread bullae and skin exfoliation

Question 47

How is staphylococcal scalded skin syndrome treated

Answer 47

IV fluids and antimicrobials

Question 48

Causes of surgical site infections

Answer 48

* Staph aureus * Coagulase negative Staphylococci * Enterococcus * E. coli * P. aeruginosa * Enterobacter * Streptococci * Fungi * Anaerobes

Question 49

Risk factors for surgical site infections

Answer 49

* DM * Smoking * Obesity * Malnutrition * Concurrent steroid use * Colonisation with Staph aureus * Procedural factors

Question 50

How are surgical site infections diagnosed

Answer 50

* Importance of sending pus/infected tissue for cultures especially with clean wound infections * Avoid superficial swabs- aim for deep structures * Consider an unlikely pathogen as a cause if obtained from a sterile site (ex bone infection) * Antibiotics to target likely organisms