Skin and soft tissue infections

Question 1

What is impetigo - what will it look like on the skin?

what organism is it due to?

Answer 1

Superficial skin infection
Multiple vesicular lesions on an erythematous base

• face, scalp

GOLDEN CRUST

Staph aureus

Question 2

Who is impetigo common in

Answer 2

children 2-5 years of age

Highly infectious

Question 3

What are some predisposing factors of impetigo

Answer 3

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

Question 4

treatment of impetigo - small vs large

Answer 4

topical antibiotics alone

Large areas need topical treatment and oral antibiotics (ex flucloxacillin)

Question 5

What is Erysipelas

• signs/symptoms

Answer 5

Infection of the upper dermis

Painful, red area (no central clearing)
Associated fever
Regional lymphadenopathy and lymphangitis
Typically has distinct elevated borders

Question 6

What is Erysipelas most commonly caused by?

Answer 6

Strep pyogenes

Question 7

Most cases of Erysipelas are on the

Answer 7

Lower limbs

Question 8

What is cellulitis

Answer 8

skin infection involving deep dermis and subcutaneous fat

Question 9

What does cellulitis present as

Answer 9

spreading erythematous area with no distinct borders

Question 10

Most likely organisms of cellulitis

Answer 10

Strep pyogenes and Staph aureus

Question 11

Gram negatives in cellulitis have a role with

Answer 11

diabetics and febrile neutropaenics

Question 12

predisposing factors of cellulitis (3)

Answer 12

Diabetes mellitus
Tinea pedis
Lymphoedema

Patients can have lymphangitis and/or lymphadenitis

Question 13

Treatment of erysipelas and cellulitis

Answer 13

combination of anti-staphylococcal and anti-streptococcal antibiotics

Question 14

Treatment of erysipelas and cellulitis

Answer 14

combination of anti-staphylococcal and anti-streptococcal antibiotics

extensive = iv antibiotics and rest

Question 15

Hair-associated infections (3)

Answer 15

Folliculitis
Furunculosis
Carbuncles

Question 16

What is Folliculitis

what do they present as?

Answer 16

Circumscribed, pustular infection of a hair follicle

small red papule
- head , back , buttocks

Question 17

Most common organism for folliculitis

Answer 17

Staph aureus

- benign condition

Question 18

Furunculosis

Answer 18

Furuncles commonly referred as boils

• single hair inflammatory nodule

Question 19

most common organism for Furunculosis

Answer 19

staph aureus

Question 20

Risk factors for Furunculosis

Answer 20

Obesity
Diabetes mellitus
Atopic dermatitis
Chronic kidney disease
Corticosteroid use

Question 21

What is a carbuncle

Answer 21

infection extends to involve multiple furuncles

• neck, post trunk

Question 22

Treatment of hair-associated infections

Folliculitis

Answer 22

no treatment or topical antibiotics

Question 23

Treatment of hair-associated infections

Furunculosis

Answer 23

no treatment or topical antibiotics. If not improving oral antibiotics might be necessary

Question 24

Treatment of hair-associated infections

Carbuncles

Answer 24

require admission to hospital, surgery and intravenous antibiotics

Question 25

Necrotising fasciitis - features

Answer 25

- infectious diseases emergencies - rapid onset - Any site may be affected Anaesthesia at site of infection is highly suggestive of this disease

Question 26

Predisposing conditions of Necrotising fasciitis include

Answer 26

``` Diabetes mellitus Surgery Trauma Peripheral vascular disease Skin popping ```

Question 27

Necrotising fasciitis - type 1

Answer 27

mixed aerobic and anaerobic infection (diabetic foot infection, Fournier’s gangrene)

Question 28

Typical organism of Necrotising fasciitis - type 1

Answer 28

``` Streptococci Staphylococci Enterococci Gram negative bacilli Clostridium ```

Question 29

Necrotising fasciitis - type 2 | - normally associated with

Answer 29

monomicrobial | Normally associated with Strep pyogenes

Question 30

Common signs of Necrotising fasciitis? systemic features?

Answer 30

Sequential development of erythema, extensive oedema and severe, unremitting pain Haemorrhagic bullae, skin necrosis and crepitus may develop fever, hypotension, tachycardia, delirium and multiorgan failure

Question 31

Antibiotics for Necrotising fasciitis

Answer 31

Flucloxacillin Gentamicin Clindamycin

Question 32

What is Pyomyositis

Answer 32

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

Question 33

Common sites of Pyomyositis

Answer 33

``` Thigh Calf Arms Gluteal region Chest wall Psoas muscle ```

Question 34

How can Pyomyositis present

Answer 34

fever, pain and woody induration of affected muscle

Question 35

Pyomyositis if untreated, can lead to ?

Answer 35

septic shock and death

Question 36

Predisposing factors of Pyomyositis include

Answer 36

``` Diabetes mellitus HIV/immunocompromised Intravenous drug use Rheumatological diseases Malignancy Liver cirrhosis ```

Question 37

Most common cause of Pyomyositis

Answer 37

Staph aureus

Question 38

How to investigate Pyomyositis

Answer 38

CT/MRI - give antibiotics

Question 39

Septic bursitis - features

Answer 39

small sac-like cavities - fluid- synovial membrane - between bon prominences and tendons

Question 40

Septic bursitis - why do you get infection / predisposing factors

Answer 40

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

Question 41

Septic bursitis - symptoms/diagnosis

Answer 41

- Fever and pain on movement also seen - Diagnosis is based on aspiration of the fluid - Most common cause is Staph aureus

Question 42

Infectious tenosynovitis

Answer 42

- synovial sheats that surround tendons | - penetrating trauma

Question 43

Infectious tenosynovitis - most common organism

Answer 43

cause Staph aureus and streptococci Chronic infections due to mycobacteria, fungi Possibility of disseminated gonococcal infection

Question 44

Infectious tenosynovitis - presentation?

Answer 44

erythematous fusiform swelling of finger Held in a semiflexed position - tenderness of tendon - empiric antibiotics

Question 45

Toxin-mediated syndromes are often due to

Answer 45

superantigens

Question 46

Toxin-mediated syndromes are mostly due to

Answer 46

some strains of Staphylococcus aureus (TSST1) (ETA +B) and Streptococcus pyogenes

Question 47

Diagnostic criteria for Staphylococcal TSS

Answer 47

``` Fever Hypotension Diffuse macular rash Three of the following organs involved Liver, blood, renal, gatrointestinal, CNS, muscular ``` ANTIBODY toxin TSST1 isolation of staph aureus

Question 48

Streptococcal TSS s almost always associated with

Answer 48

presence of Streptococci - much higher mortality than streptococcal - URGENT surgical debridement

Question 49

Treatment of TSS (5)

Answer 49

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

Question 50

Staphylococcal scalded skin syndrome is infection due to

Answer 50

particular strain of Staph aureus producing the exfoliative toxin A or B

Question 51

Staphylococcal scalded skin syndrome - treatment

Answer 51

intravenous fluids and antimicrobials

Question 52

Staphylococcal scalded skin syndrome is characterised by

Answer 52

widespread bullae and skin exfoliation

Question 53

What is the Panton-Valentine leucocidin toxin can be transferred from?

Answer 53

gamma haemolysin Staph aureus to another, including MRSA

Question 54

Panton-Valentine leucocidin toxin can go on to cause

Answer 54

SSTI and haemorrhagic pneumonia

Question 55

Panton-Valentine leucocidin toxin - patients present with

Answer 55

recurrent boils which are difficult to treat | Treat with antibiotics that reduce toxin production

Question 56

Intravenous-catheter associated infections - what type of infection? Normally start off as what? can have associated?

Answer 56

Nosocomial infection SST inflammation progressing to cellulitis and even tissue necrosis bacteraemia

Question 57

Risk factors for Intravenous-catheter associated infections (4)

Answer 57

Continuous infusion >24 hours Cannula in situ >72 hours Cannula in lower limb Patients with neurological/neurosurgical problems

Question 58

Intravenous-catheter associated infections - most common organism? how do they work? How is a diagnosis made

Answer 58

Staph aureus (MSSA and MRSA) Commonly forms a biofilm which then spills into bloodstream clinically or positive blood cultures

Question 59

Intravenous-catheter associated infections - treatment ?

Answer 59

to remove cannula Express any pus from the thrombophlebitis Antibiotics for 14 days Echocardiogram

Question 60

Intravenous-catheter associated infection - methods of prevention (5)

Answer 60

Do not leave unused cannula Do not insert cannulae unless you are using them Change cannulae every 72 hours Monitor for thrombophlebitis Use aseptic technique when inserting cannulae

Question 61

Surgical site infections - what are the 4 classes

Answer 61

1 - clean wound 2- clean- contaminated 3- contaminated 4- infected wound

Question 62

List some Causes of Surgical site infections

Answer 62

``` Staph aureus (incl MSSA and MRSA) Coagulase negative Staphylococci Enterococcus Escherichia coli Pseudomonas aeruginosa Enterobacter Streptococci Fungi Anaerobes ```

Question 63

Risk factors for surgical site infections - PATIENT associated

Answer 63

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

Question 64

Risk factors for surgical site infection - Procedural factors (7)

Answer 64

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

Question 65

Diagnosis of surgical site infections (4 main)

Answer 65

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