SSTIs and PUO Flashcards

1
Q

How does the treatment of cellulitis and infections of the skin above differ from necrotising fasciitis and the layers below?

A

Cellulitis and above → just ABs

Nec Fasc and below → ABs + surgical debridement (+ usually no empirical ABs, need to confirm organism with surgical sample)

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2
Q

What are the classical features of cellulitis and how does it differ from erysipelas?

A

Both usually hot, red, tender
Cellulitis involved SQ → more diffuse margin compared to erysipelas

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3
Q

What are the classical features of impetigo?

A

In children, perioral, starts as vesicle → ruptures releasing yellowish, thick, wet crust

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4
Q

What is the main causative organism for cellulitis?

A

1) Staph Aureus
2) ß-hemolytic strep (esp. GAS)

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5
Q

What is the main causative organism for impetigo?

A

1) Staph Aureus
2) ß-hemolytic strep (esp. GAS)

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6
Q

What is the main causative organism for folliculitis?

A

1) Staph Aureus
2) ß-hemolytic strep (esp. GAS)
3) Pseudomonas aeruginosa (hot tub folliculitis)

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7
Q

What is the main causative organism for furuncles?

A

1) Staph Aureus
2) ß-hemolytic strep (esp. GAS)

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8
Q

What is the main causative organism for carbuncles?

A

1) Staph Aureus
2) ß-hemolytic strep (esp. GAS)

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9
Q

What is the main causative organism for erysipelas?

A

1) Group A strep

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10
Q

What are the classical features of lymphangitis?

A

Red tracking linear streaks towards regional lymph nodes, which are enlarged and tender
- may present with swollen limb

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11
Q

What is the main causative organism for lymphangitis?

A

1) Group A strep (acute)
2) Pasteurella multocida (cat scratch, acute)
3) Filariasis
4) Mycobacterium marinum (swimming pool granuloma, chronic)
5) Sporothrix schenckii (rose thorn, chronic)

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12
Q

What are the classical features of intertrigo?

A

chronic, subtle onset of pruritus, burning, tingling, and pain in the skin folds and flexural surfaces
- esp in high BMI and DM px

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13
Q

What are 2 common causative organisms of intertrigo?

A

1) Staph aureus
2) Candida
3) Coliforms

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14
Q

How do type 1 and 2 necrotising fasciitis differ?

A

1) Area:
1: mainly perineal, genital, perianal
2: mainly lower limbs

2) Pain
2: classically out of proportion with skin appearance

3) Causative organisms
1: polymicrobial
2: group A strep, Staph aureus

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15
Q

What are 2 common causative organisms of gas gangrene (myonecrosis)?

A

1) Clostridium perfringens (necrotic tissue)
2) Spontaneous/hematogenous (group A strep)

Immunocompromised/w risk factors:
3) Clostridia
4) Staph aureus
5) Vibro vulnificus

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16
Q

What must be done before collecting a swab from a diabetic foot ulcer?

A

Cleanse and debride superficial layer to remove other organisms

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17
Q

What is needed to guide antibiotic therapy in a chronic wound/ diabetic foot ulcer?

A

Deep tissue culture

18
Q

How do the typical causative organism for diabetic foot ulcers differ for (i) a new onset infection (ii) chronic wounds?

A

i) Staph aureus/Group A Strep

ii) Gram neg/mixture of gram neg and pos

19
Q

What are 5 microbiological testing options for SSTIs?

A

1) WET wound swab (dry=skin flora)

2) Skin scrapings
- scabies, skin fungal infection

3) Pus swab

4) Pus aspirate

5) Tissue culture
- myositis/nec fasc

6) Deep tissue culture/biopsy
- diabetic foot uclers

7) Blood culture
- septic/pyrexial px

20
Q

How does hematogenous osteomyelitis differ in children and adults?

A

Children: long bones (tibia and femur)
Adults: adjacent vertebral bodies

21
Q

What is the main causative organisms of hematogenous osteomyelitis?

A

1) Staph aureus

If <1y/o
2) Coag neg staph
3) GBS
4) E coli

22
Q

What are 2 main causative organisms of osteomyelitis by contiguous spread?

A

1) Staph aureus
2) GAS
3) CONS (prosthesis)

23
Q

What are 2 ways to diagnose osteomyelitis?

A

1) MRI
2) Tissue culture (must take in OT)
3) CT guided biopsy

24
Q

Should empirical antibiotics be given for a px with suspected osteomyelitis?

A

NO
- decreases chances of growing causative organism

25
Q

How long is the typical antibiotic course for osteomyelitis?

A

at least 6 weeks

26
Q

What are 2 main causative organisms of prosthetic joint infections?

A

1) Coagulative negative staph
2) Staph aureus

27
Q

Should empirical antibiotics be given for a px with suspected prosthetic joint infection?

A

No
- decreases chances of growing causative organism

28
Q

How is a prosthetic joint infection diagnosed?

A

NOT gram stain
- need to culture → intraoperative tissue/pis

29
Q

What are 2 ways to treat prosthetic joint infections?

A

1) 1 stage exchange arthroplasty
- change new prosthesis with same operation with antibiotic loaded cement

2) 2 stage approach
i) remove infected prosthesis
ii) install antibiotic loaded cement + spacer to stabilise bone
iii) insert new prosthesis after prolonged course of antibiotics

30
Q

How are antibiotics typically administered for osteomyelitis/prosthetic joint infections?

A

IV
- oral only if excellent OF

31
Q

True or false: acute monoarticular arthritis is septic arthritis until otherwise proven

A

True

32
Q

What is the main causative organism of septic arthritis?

A

Staph aureus

33
Q

How is septic arthritis typically diagnosed?

A

Joint aspiration:
1) High WCC (w predominance of neutrophils)
2) Gram stain
3) Culture

34
Q

How is septic arthritis treated?

A

1) Joint washout
2) 2-6 weeks of ABs

35
Q

What is the clinical definition of PUO?

A

1) illness >3wks
2) >38.3°C on several occasions
3) No diagnosis after 1 wk of routine workup in hospital

36
Q

True or false: A documented pattern of fever using a electronic thermometer taken at 7am daily is enough to narrow a diagnosis for PUO.

A

False.
- Need to take w electronic thermometer
- need to measure BOTH 6am and 6pm to exclude exaggerated circadian rhythm
- pattern of fever insufficient to diagnose

37
Q

What are the 3 main causes of PUO?

A

1) Infection
2) Neoplasm
3) Autoimmune disease

Others:
4) Drugs
5) Factitious fever
6) Pulmonary emboli
7) Familial Mediterranean fever

38
Q

Should a px with PUO be given broad-spectrum empirical antibiotics to reduce morbidity?

A

No.
- discontinue ABs for 1 wk prior to Ix if safe

39
Q

What are 3 infective causes of PUO?

A

1) Abscess
2) Endocarditis
3) Osteomyelitis
4) Biliary infection
5) Pyelonephritis (subacute)
6) TB
7) Brucellosis
8) Viral infection/cryptococcus/histoplasmosis/toxoplasmosis/malaria

40
Q

What are 2 neoplastic causes of PUO?

A

1) Lymphoma (esp. hodgkin’s)
2) Leukemia
3) Primary hepatoma (metastatic rarely pyretic)
4) Renal cell
5) Atrial myxoma

41
Q

What are 3 autoimmune causes of PUO?

A

1) SLE
2) Still’s disease (adult onset juvenile RA)
3) Polymyalgia rheumatica (elderly w temporal arteritis)
4) Polyarteritis nodosa
5) Mixed connective tissue disease
6) Subacute thyroiditis
7) Kikuchi’s disease (young asian F with generalised lymphadenopathy)

42
Q

Should anti-pyretics be given to px with PUO?

A

Yes only once fever episodes are documented