Skin and soft tissue infections Flashcards

1
Q

What is the most distinguishing clinical feature of Impetigo?

A

Golden crust - the vesicular lesions that form with the infection rupture and ooze substances that form golden crust

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Predisposing factors for impetigo?

A
  • Skin abrasions
  • Minor trauma
  • Burns
  • Poor hygiene
  • Insect bites
  • Chickenpox
  • Eczema
  • Atopic dermatitis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Treatment of impetigo

A

Small areas can be treated with topical antibiotics alone

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Most common causative organism in Erysipelas?

A

Strep pyogenes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe how an Erysipelas infection presents

A
  • Infection of the upper dermis - typically has distinct elevated borders i.e you can feel where it starts and ends
  • Painful, red area
  • Associated fever and regional lymphadenopathy and lymphangitis
  • 70-80% of cases involves the lower limbs, 5-20% affect the face
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How would you treat Erysipelas?

A

A combination of anti-staphylococcal and anti-streptococcal antibiotics i.e flucloxacillin, clarithromycin or co-amoxiclav etc

In extensive disease, admission for intravenous antibiotics and rest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How would you treat Cellulitis?

A

1st line = flucloxacillin, clarithryomycin, co-amoxiclav

In extensive disease, admission for intravenous antibiotics and rest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is cellulitis?

A

Diffuse infection of the skin and the soft tissues underneath (deep dermis and subcutaneous fat)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the most likely causative organisms for cellulitis? (3)

A

Staph aureus Strep pyogenes Strep dysgalactiae MRSA also can be a cause

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does cellulitis present?

A
  • Presents as a spreading erythematous area with no distinct borders
  • Fever is common
  • Regional lymphadenopathy and lymphangitis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are some common predisposing factors of cellulitis?

A
  • DM
  • Tinea pedis ‘athletes’ foot’
  • Lymphoedema
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is folliculitis?

A
  • An infection of one hair follicle that has not extended beyond
  • Small red papules with purulent centre
  • Benign
  • Typically found on head, back, buttocks and extremities
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is furunculosis?

A
  • This is otherwise known as a boil
  • The infection has breached the hair follicle to extend to the surrounding areas
  • Usually affects moist, hairy, friction-prone areas of body (face, axilla, neck, buttocks)
  • May spontaneously drain purulent material
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are carbuncles?

A
  • Known as an abscess of the skin – involves numerous hair follicles
  • Often located back of neck, posterior trunk or thigh
  • Purulent material may be expressed from multiple sites + systemic features
  • Can require hospital admission, surgical drainage + IV antibiotics
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the most common organism causing folliculitis and furunculosis?

A

Staph aureus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Is there any treatment for folliculitis or furunculosis?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Treatment of Carbuncles

A

Often require admission to hospital, surgery and IV antibiotics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is necrotising faciitis?

A

One of the infectious diseases emergencies affecting the fascia (deepest part of the skin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What can predispose you to necrotising fasciitis?

A
  • DM
  • Surgery
  • Trauma
  • Peripheral vascular disease
  • Skin popping - injecting illicit drugs into the dermis or subcutaneous tissue with the goal of achieving slower absorption, decreased risk of overdose, or easier administration than with IV drug administration.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is type 1 necrotising fasciitis? Give examples

A
  • Type I refers to a mixed aerobic and anaerobic infection i.e. diabetic foot infection, Fournier’s gangrene
  • Typical organisms include:-
    • Streptococci
    • Staphylococci
    • Enterococci
    • Gram negative bacilli
    • Clostridium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is type 2 necrotising fasciitis? And which organism is it normally associated with?

A
  • Type II is monomicrobial
  • Strep pyogenes
22
Q

How does necrotising fasciitis present?

A
  • Rapid onset
  • Sequential development of erythema, extensive oedema and severe, unremitting pain
  • Development of haemorrhagic bullae, skin necrosis and crepitus
  • Systemic features include fever, hypotension, tachycardia, delirium and multiorgan failure
23
Q

Management of necrotising fasciitis

A
  • Surgical review is mandatory
  • Antibiotics should be broad spectrum i.e. Flucloxacillin, Gentamicin or Clindamycin
  • Mortality can be as high as 40%
24
Q

What is pyomyositis?

A
  • Purulent infection deep within striated muscle, often manifesting as an abscess
  • Common sites include: Thigh, Calf, Arms, Gluteal region, Chest wall or Psoas muscle
25
Q

How might pyomyositis present?

A

With fever, pain and woody induration of affected muscle (stiff/hardened muscle)

26
Q

If pyomyositis is left untreated what can it lead to?

A

Septic shock and death

27
Q

What organisms cause pyomyositis?

A

Staph A, TB and fungi also

28
Q

How is pyomyositis treated?

A

Drainage with antibiotic cover depending on Gram stain and culture results

29
Q

What is septic bursitis?

A

Bursae are small sac-like cavities that contain fluid and are lined by synovial membrane. They are found subcutaneously between bony prominences or tendons and help facilitate movement with reduced friction. These can become infected and this is often from adjacent skin infection

Diagnosis is based on aspiration of the fluid

30
Q

Predisposing factors for septic bursitis? (6)

A
  • Rheumatoid arthritis
  • Alcoholism
  • DM
  • IV drug abuse
  • Immunosuppression
  • Renal insufficiency
31
Q

What is infectious tenosynovitis?

A
  • Infection of the synovial sheats that surround tendons
  • Penetrating trauma often creates opportunity for Staph A and streptococci infection
32
Q

Which tendons are most commonly involved in infectious tenosynovitis?

A

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

33
Q

How does infectious tenosynovitis present?

A
  • Erythematous fusiform swelling of finger
  • Tenderness over the length of the tendon sheat and pain with extension of finger are classical
34
Q

How should infectious tenosynovitis be managed?

A

Empiric antibiotics

Hand surgeon to review ASAP

35
Q

What is a toxin mediated syndrome?

A

Conditions/illnesses that are caused by the toxins that organisms produce They are often due to superantigens

36
Q

What do superantigens do?

A

They bypass normal communication between antigen presenting cell and T cells. This means the T cell receptors will be activated straight away and there will be a massive burst in cytokine release and this leads to septic shock

37
Q

How does the normal immune system deal with a pathogen?

A

The foreign organism is taken up by antigen presenting cell and it degrades the organism. The APC then presents the antigens to T cells which activate the production of antibodies by cytokines

38
Q

Which organisms are strongly associated with toxin-mediated syndromes?

A
  • Staph A - TSST1, ETA and ETB
  • Strep Pyogenes - TSST1
39
Q

How would a Staphylococcal Toxic shock syndrome present?

A
  • Fever
  • Hypotension
  • Diffuse macular rash
  • Multi-system organ involvement
  • Isolation of Staph aureus from mucosal or normally sterile sites
  • Production of TSST1 by isolate
  • Development of antibody to toxin during convalescence
40
Q

How would a Streptococcal Toxic shock syndrome present?

A
  • MORE SERIOUS - mortality rate is much higher than staph
  • Almost always associated with presence of Streptococci in deep seated infections such as erysipelas or necrotising fasciitis
  • Treatment necessitates urgent surgical debridement of the infected tissues
41
Q

How do you treat toxic shock?

A
  • Remove offending agent (ex tampon) IV fluids
  • Antibiotics
  • IV immunoglobulins - to help fight infection - uncommon due to shortage
  • Inotropes - sometimes used - targets the heart’s contractility
42
Q

What sorts of things can cause toxic shock? (2)

A
  • Tampon use
  • Small skin infections due to staph Aureus secreting TSST1
43
Q

Exfoliative toxin A or B causes which toxin induced infection?

A

Staphylococcal scalded skin syndrome This causes skin to peel off. Common in children

44
Q

How do IV catheter associated infections normally start?

A

Normally starts as local skin and soft tissue inflammation progressing to cellulitis and even tissue necrosis Commonly forms a biofilm which then spills into bloodstream

45
Q

Most common organism causing IV catheter infections

A

Staph A (MSSA and MRSA)

46
Q

Treatment of an IV catheter associated infection

A
  • Treatment is to remove cannula and express any pus from the thrombophlebitis
  • Antibiotics for 14 days Prevention is more important
  • Echo - if there is associated bacteraemia as there is potential that the infection has spread and caused endocarditis
47
Q

How to prevent a IV catheter infection

A
  • 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
48
Q

What are the 4 classes of Surgical site infections?

A

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

49
Q

Causes of surgical site infections

A

Any organism but most common = Staph aureus - MSSA and MRSA

50
Q

Patient associated risk factors for surgical site infections

A

DM Smoking Obesity Malnutrition Concurrent steroid use - immunosuppressed

51
Q

Procedural risk factors for surgical site infections

A
  • Shaving of site the night prior to procedure
  • Improper preoperative skin preparation
  • Improper antimicrobial prophylaxis
  • Break in sterile technique
  • Inadequate theatre ventilation
  • Perioperative hypoxia
52
Q

Look

A

Infections that need urgent attention:-

  • Necrotising fasciitis
  • Pyomyositis
  • Toxic shock syndrome
  • PVL infections