Skin and Soft Tissue Infections

Question 1

What are two common organisms that cause impetigo?

Answer 1

S. Aureus

S. Pyogenes

Question 2

What is the treatments for small and large areas of impetigo?

Answer 2

Topical antibiotics for small areas

Topical and oral (except penicillin) for large areas

Question 3

What is the causative organism for erysipelas?

Answer 3

S. Pyogenes

Question 4

What are three pre-disposing factors for cellulitis?

Answer 4

Diabetes mellitus
Tinea pedis
Lymphoedema

Question 5

What are the causative organisms for cellulitis?

Answer 5

S. Aureus

S. Pyogenes

Question 6

What are the treatments for cellulitis and erysipelas?

Answer 6

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

Question 7

What is the causative organism of folliculitis?

Answer 7

S. Aureus

Question 8

What is furunculosis?

Answer 8

Furuncles commonly referred as boils
Single hair follicle-associated inflammatory nodule
Extending into dermis and subcutaneous tissue

Question 9

What is a carbuncle?

Answer 9

Occurs when infection extends to involve multiple furuncles
Often located back of neck, posterior trunk or thigh
Multiseptated abscesses
Purulent material may be expressed from multiple sites
Constitutional symptoms common

Question 10

What are the treatments for hair associated infections?

Answer 10

Topical antibiotics for folliculitis and furunculosis

IV antibiotics for carbuncle

Question 11

What are predisposing conditions for necrotising fasciitis?

Answer 11

Diabetes mellitus
Surgery
Trauma
Peripheral vascular disease
Skin popping

Question 12

What are the causative organisms for type 1 NF?

Answer 12

Streptococci
Staphylococci
Enterococci
Gram negative bacilli
Clostridium

Question 13

What is the causative organism for type 2 NF?

Answer 13

S. Pyogenes

Question 14

What are the features of NF?

Answer 14

Rapid onset
Sequential development of erythema, extensive oedema and severe, unremitting pain
Haemorrhagic bullae, skin necrosis and crepitus may develop
Systemic features include fever, hypotension, tachycardia, delirium and multiorgan failure
Anaesthesia at site of infection is highly suggestive of this disease

Question 15

What is the management for NF?

Answer 15

Surgical review is mandatory
Imaging may help but could delay treatment 
Antibiotics should be broad spectrum 
Flucloxacillin
Gentamicin
Clindamycin

Question 16

What is the presentation of pyomyositis?

Answer 16

Purulent infection deep within striated muscle, often manifesting as an abscess
Infection is often secondary to seeding into damaged muscle
Can present with fever, pain and woody induration of affected muscle

Question 17

What are the causative organisms for pyomyositis and what is the management?

Answer 17

Commonest cause is Staph aureus
Other organisms can be involved including Gram positive/negatives, TB and fungi
Management is drainage of affected muscle and antibiotics depending on gram stain results

Question 18

What are predisposing factors for septic bursitis?

Answer 18

Infection is often from adjacent skin infection
Other predisposing factors include
Rheumatoid arthritis
Alcoholism
Diabetes mellitus
Intravenous drug abuse
Immunosuppression
Renal insufficiency

Question 19

What is the presentation of septic bursitis?

Answer 19

Peri bursal cellulitis, swelling and warmth are common

Fever and pain on movement also seen

Question 20

What is the causative organism for septic bursitis and how is it diagnosed?

Answer 20

S. Aureus most common
Gram negatives
Mycobacteria
Brucella
Diagnosis from cytology of fluid

Question 21

What is infectious tenosynovitis?

Answer 21

Infection of the synovial sheaths that surround tendons

Flexor muscle-associated tendons and tendon sheaths of the hand most commonly involved

Question 22

What are the causative organisms of infectious tenosynovitis?

Answer 22

Most common cause Staph aureus and streptococci

Chronic infections due to mycobacteria, fungi

Question 23

What is the presentation of infectious tenosynovitis?

Answer 23

Present with erythematous fusiform swelling of finger
Held in a semi-flexed position
Tenderness over the length of the tendon sheath and pain with extension of finger are classical

Question 24

What are the features of staphylococcal TSS?

Answer 24

Fever
Hypotension
Diffuse macular rash
Three of the following organs involved
Liver, blood, renal, gastrointestinal, CNS, muscular
Isolation of Staph aureus from mucosal or normally sterile sites
Production of TSST1 by isolate
Development of antibody to toxin during convalescence

Question 25

What can deep seated streptococcal infections lead to?

Answer 25

Streptococcal TSS

Question 26

What are the treatments for TSS?

Answer 26

``` Remove offending agent (ex tampon) Intravenous fluids Inotropes Antibiotics Intravenous immunoglobulins ```

Question 27

What toxin is the cause of STSS and haemorrhagic pneumonia?

Answer 27

Panton-Valentine leucocidin toxin

Question 28

What are the four classifications of surgical wound infections?

Answer 28

Class I: Clean wound (respiratory, alimentary, genital or infected urinary systems not entered) Class II: Clean-contaminated wound (above tracts entered but no unusual contamination) Class III: Contaminated wound (Open, fresh accidental wounds or gross spillage from the gastrointestinal tract) Class IV: Infected wound (existing clinical infection, infection present before the operation

Question 29

What are patients risk factors for a surgical wound infection?

Answer 29

``` Diabetes Smoking Obesity Malnutrition Concurrent steroid use Colonisation with Staph aureus ```

Question 30

What are procedural risk factors for a surgical wound infection?

Answer 30

``` Shaving of site the night prior to procedure Improper preoperative skin preparation Improper antimicrobial prophylaxis Break in sterile technique Inadequate theatre ventilation Perioperative hypoxia ```