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Diseases > Skin and soft tissue infections, Diseases, Yr 3, Wk 1 > Flashcards

Skin and soft tissue infections, Diseases, Yr 3, Wk 1 Flashcards

1
Q

What skin compartment(s) does each of these infections affect and what is the etiologic organism?
a) Impetigo

b) Folliculitis
c) Erysipelas
d) Cellulitis
e) Necrotizing fascitiitis

A

a) Impetigo: Epidermis, S. aureus, Strep. pyogenes
b) Folliculitis: hair follicle which goes through the dermis and the epidermis, S. aureus
c) Erysipelas: Upper Dermis and some of the subcutaneous fat, Strep. pyogenes
d) Cellulitis: Deep Dermis (some of) and the subcutaneous fat, Strep. pyogenes (common), Staph aureus (uncommon), H. Influenzae (rare)
e) Necrotizing fasciitis Subcutaneous fat, fascia, Strep pyogenes or Mixed bowel flora

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2
Q

List some things to consider in skin and soft tissue infections:

A
  • Site: possible complication with specific sites (ex: abdo, face)
  • Organism
  • Host: diabetes leading to neuropathy and vasculopathy, immunosuppression, renal failure, Milroy’s disease, Predisposing skin conditions (ex; atopic dermatitis)

-Environment:
Drug-resistant strains (MRSA), Drug interactions, Drug allergies

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3
Q

Describe Impetigo:

A
  • Superficial skin condition
  • Multiple vesicular lesions on an erythmatous base
  • Golden crust is highly suggestive of this diagnosis (chin area in the photo given)
  • Most commonly due to Staph Aureus
  • Less commonly Strep pyogenes
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4
Q

Give some more information on Impetigo:

A
  • Common in children 2-5 years of age
  • Highly infectious
  • Usually occurs on exposed parts of the body including face, extremities and scalp

-Look for predisposing factors:
Skin abrasions, Minor trauma, Burns, Poor hygiene, Insect bites, Chickenpox, Eczema, Atopic dermatitis

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5
Q

What is the treatment for Impetigo?

A
  • Small areas can be treated with topical antibiotics alone

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

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6
Q

Describe Erysipelas:

A
  • Infection of the UPPER DERMIS
  • Painful, red area (No central clearing)
  • Associated fever
  • Regional lymphadenopathy and lymphangitis
  • Typically has distinct elevated borders
  • Most commonly due to Strep pyogenes

(picture is red area on arm (large red area)

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7
Q

What body part is most affected in erysipelas?

A
  • 70-80% of cases involves the lower limbs
  • 5-20% affect the face
  • Tends to occur in areas of pre-existing lymphoedema, venous stasis, obesity, paraparesis, diabetes mellitus
  • May involve intact skin
  • High recurrence rate (30% within 3 years)
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8
Q

Describe Cellulitis:

A
  • Diffuse skin infection involving DEEP DERMIS and subcutaneous fat
  • Presents as a spreading erythematous area with NO DISTINCT BORDERS
  • Most likely organisms are Strep pyogenes and Staph aureus
  • Remember role of Gram negatives in diabetics and febrile neutropaenics
  • Fever is common
  • Regional lymphadenopathy and lymphangitis
  • Possible source of bacteraemia
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9
Q

In cellulitis, what are some predisposing factors?

A
  • DM
  • Tinea pedis
  • Lymphoedema

Patients can have lymphangitis and/or lymphadenitis

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10
Q

What is the treatment of erysipelas and cellultis?

A
  • A combination of anti-staphylococcal and anti-streptococcal antibiotics
  • In extensive disease, admission for intravenous antibiotics and rest
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11
Q

Name 3 Hair-associated infections:

A
  • Folliculitis
  • Furunculosis
  • Carbuncles
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12
Q

Describe Folliculitis:

A
  • Circumscribed, pustular infection of a hair follicle
  • Up to 5mm in diameter
  • Present as small red papules
  • Central area of purulence that may rupture and drain
  • Typically found on head, back, buttocks and extremities
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13
Q

What is the most common organism associated with Folliculitis?

A

Staph aureus

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14
Q

Is folliculitis a benign condition?

A

YES

Constitutional symptoms not often seen

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15
Q

Describe Furunculosis:

A
  • Furuncles commonly referred to as boils
  • Single hair follicle-associated inflammatory nodule
  • Extending into dermis and subcutaneous tissue
  • Usually affected moist, hairy, friction-prone areas of body (face, axilla, neck, buttocks)
  • May spontaneously drain purulent material
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16
Q

What is the most common causative organism in Furunculosis?

A

Staph Aureus is the most common organism

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17
Q

Are systemic symptoms common in Furunculosis?

A

No

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18
Q

What are some risk factors in Furunculosis?

A
  • Obesity
  • Diabetes mellitus
  • Atopic dermatitis
  • Chronic kidney disease
  • Corticosteroid use
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19
Q

Describe Carbuncles:

A
  • 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
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20
Q

Whats the treatment of (hair associated infection) Folliculitis?

A

No treatment or topical antibiotics

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21
Q

Whats the treatment of furunculosis (hair associated infection)?

A

No treatment or topical antibiotics

If not improving oral antibiotics might be necessary

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22
Q

What is the treatment of carbuncles?

A

Carbuncles often require admission to hospital, surgery and intravenous antibiotics

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23
Q

Describe Necrotising fasciitis:

A
  • One of the infectious diseases emergencies

- Any site may be affected

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24
Q

What are some predisposing conditions for Necrotising fasciitis?

A
  • DM
  • Surgery
  • Trauma
  • Peripheral vascular disease
  • Skin popping
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25
Q

What is Type I necrotising fasciitis?

A

Type I refers to a mixed aerobic and anaerobic infection (diabetic foot infection, Fournier’s gangrene)

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26
Q

What are some TYPICAL organisms that cause Type I Necrotising fasciitis?

A

Typical organisms include:
-Streptococci

  • Staphylococci
  • Enterococci
  • Gram negative bacilli
  • Clostridium
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27
Q

What is Type II Necrotising fasciitis?

A
  • Type II is monomicrobial

- Normally associated with Strep pyogenes

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28
Q

Give some more information of Necrotising fasciitis?

A
  • 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
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29
Q

What is mandatory in Necrotising fasciitis?

A

Surgical review

Imaging may help but could delay treatment

30
Q

What type and give names of antibiotics used in Necrotising fasciitis:

A

Antibiotics should be broad spectrum

  • Flucloxacillin
  • Gentamicin
  • Clindamycin

(Overall mortality ranges between 17-40%)

31
Q

What is pyomyositis?

A
  • Purulent infection deep within striated muscle, often manifesting as an abscess
  • Infection is often secondary to seeding into damaged muscle
  • Multiple sites involved in 15%
-Common sites include: 
Thigh
Calf
Arms
Gluteal region 
Chest wall 
Psoas muscle
32
Q

How can Pyomyositis present?

A

-Can present with fever, pain and woody induration of affected msucle

33
Q

What happens if Pyomyositis is untreated?

A

If untreated can lead to septic shock and death

34
Q

What are some predisposing factors in pyomyositis?

A
  • DM
  • HIV/ immunocompromised
  • IVDA
  • Rheumatological diseases
  • Malignancy
  • Liver cirrhosis
35
Q

What is the commonest cause of Pyomyositis?

A

Staph aureus

36
Q

How would you investigate Pyomyositis?

A

CT/ MRI

37
Q

What is the treatment of Pyomyositis?

A

Treatment is drainage with antibiotic cover depending on Gram stain and culture results

38
Q

What is septic bursitis?

A
  • Bursae are small sac-like cavities that contain fluid and are lined by synovial membrane
  • Located subcutaneously between bony prominences or tendons
  • Facilitate movement with reduced friction
  • Most common include patellar and olecranon
39
Q

In septic bursitis, where is infection often from?

A

adjacent skin infection

40
Q

What are some predisposing factors of septic bursitis ?

A
  • Rheumatoid arthritis
  • Alcoholism
  • DM
  • IVDA
  • Immunosuppression
  • Renal insufficiency
41
Q

What are some common associated features in septic bursitis?

A
  • Peribursal cellulitis, swelling and warmth are common
  • Fever and pain on movement also seen
  • Diagnosis is based on aspiration of the fluid
  • Most common cause is Staph aureus
42
Q

What is infectious tenosynovitis?

A

Infection of the synovial sheaths that surround tendons

  • flexor muscle associated tendons and tendon sheats of the hand most common
  • Penetrating trauma is the most common inciting event
  • most common cause is staph aureus and streptococci
  • chronic infections due to mycobacteria, fungi
  • possibility of disseminated gonococcal infection
43
Q

How does infectious tenosynovitis usually present?

A
  • present with erythematous fusiform swelling of finger
  • held in semiflexed position
  • tenderness over the length of the tendon sheat and pain with extension of finger
44
Q

What is the treatment of infectious tenosynovitis?

A
  • Empiric antibiotics

- Hand surgeon to review ASAP

45
Q

What are Toxin-mediated syndromes often due to?

A

Superantigens

46
Q

Give some information on toxin-mediated syndromes?

A
  • group of pyrogenic exotoxins
  • do not activate immune system via normal contact between APC and T cells
  • superantigens bypass this and attach directly to the T cell receptors activating up to 20% of the total pool of T cells instead of the normal 1/10,000
  • massive burst of cytokine release
  • leads to endothelial leakage, haemodynamic shock, multi-organ failure and death??
47
Q

what are toxin-mediated syndromes mostly due to?

A

some strains of staph aureus and streptococcus pyrogenes;

  • staph aureus: TSST1, ETA and ETB
  • strep pyogenes: TSST1
48
Q

What is toxic shock syndrome?

A
  • came about due to association with the use of high-absorbency tampons during menses
  • can also be due to small skin infections due to staph aureus secreting TSST1
49
Q

What is the diagnostic criteria for staphylococcal Toxic shock syndrome?

A
  • 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
50
Q

What is STREPTOCOCCAL TOXIC SHOCK SYNDROME almost associated with?

A

the presence of streptococci in deep seated infections such as erysipelas or necrotising fasciitis

(-mortality rate is much higher than staphylococcal 50% vs 5%)

51
Q

what does treatment require in streptococcal TSS?

A

treatment necessitates urgent surgical debridement of the infected tissues

(removal of the infected tissues)

52
Q

describe the treatment of TSS:

A
  • REMOVE OFFENDING AGENT (EX TAMPON)
  • Intravenous fluids
  • Inotropes
  • Antibiotics
  • Intravenous immunoglobulins
53
Q

What is staphylococcal scalded skin syndrome?

A
  • infection due to a particular strain of staph aureus producing the exfoliative toxin A or B
  • characterised by widespread bullae and skin exfoliation
  • usually occurs in children but rarely in adults as well
54
Q

What is the treatment of SSSS?

A

-treatment with intravenous fluids and antimicrobials

55
Q

What is Panton-Valentine leucocidin toxin?

A
  • it is a gamma haemolysin
  • can be transferred from one strain of staph aureus to another, including MRSA
  • can cause SSTI and haemorrhagic pneumonia
  • children and young adults affected
56
Q

How do patients present with Panton-Valentine leucocidin toxin?

A

patients present with recurrent boils which are difficult to treat

-treat with antibiotics that reduce toxin production

57
Q

What type of infection is an intravenous-catheter associated infection?

A

nosocomial infection (got it in hospital)

58
Q

Describe the progression of an IV-catheter associated infection:

A

normally starts as local SST inflammation progressing to cellulitis and even tissue necrosis

-common to have associated bacterameia

59
Q

What are some risk factors for an intravenous-catheter associated infection?

A
  • continuous infusion >24 hours
  • Cannula in situ >72 hours
  • Cannula in lower limb
  • Patients with neurological/ neurosurgical problems
60
Q

What is the most common organism involved in an IV-catheter associated infection and describe how it occurs? :

A
  • Most common organism is Staph aureus (MSSA and MRSA)
  • commonly forms a BIOFILM which then spills into bloodstream
  • can seed into other places (ex endocarditis, osteomyelitis)
  • diagnosis made clinically or by positive blood cultures
61
Q

What is the treatment of an IV catheter associated infection?

A
  • treatment is to remove cannula
  • express any pus from the thrombophlebitis
  • antibiotics for 14 days
  • echocardiogram
62
Q

Prevention is more important in an IV- catheter associated infection, what would be some means of prevention?

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
63
Q

SURGICAL SITE INFECTIONS: classification of surgical wounds- what are the 4 classes?

A

Class I, class II, Class III, Class IV

class I-IV

64
Q

What is a class I type surgical site infection?

A

Class I: Clean wound (respiratory, alimentary, genital or infected urinary systems not entered)

65
Q

What is a class III type surgical site infection?

A

Class III: Contaminated wound (Open, fresh accidental wounds or gross spillage from the gastrointestinal tract)

66
Q

What is a class IV type surgical site infection?

A

Class IV: Infected wound (existing clinical infection, infection present before the operation)

67
Q

List some causes of surgical site infections:

A
  • Staph aureus (incl MSSA and MRSA)
  • Coagulase negative Staphylococci
  • Enterococcus
  • Escherichia coli
  • Pseudomonas aeruginosa
  • Enterobacter
  • Streptococci
  • Fungi
  • Anaerobes
68
Q

What are some risk factors for surgical site infections?

A

Patient associated:
-Diabetes

  • Smoking
  • Obesity
  • Malnutrition
  • Concurrent steroid use
  • Colonisation with Staph aureus
69
Q

What are some risk factors for surgical site infections: PROCEDURAL FACTORS?

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
70
Q

Describe the diagnosis of surgical site infections:

A
  • 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 (ex bone infection)
  • Antibiotics to target likely organisms
71
Q

What are some soft tissue infections that need URGENT attention?

A
  • Necrotising fasciitis
  • Pyomyositis
  • Toxic shock syndrome
  • PVL infections
  • Venflon-associated infections

(treat or manage predisposing factors)

Diseases (9 decks)

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