Skin and Soft Tissue Infection

Question 1

Cellulitis

1. Define
2. Define Erysipelas
3. Define Cellulitis

Answer 1

1. Inflammation of the skin and subcutaneous tissues
2. upper dermis and superficial lymphatics
3. involves deeper dermis and subcutaneous fat

Question 2

Cellulitis Presentation

1. Signs/Symptoms (4)
2. Predisposing factors (5)
3. Common Sites (3)

Answer 2

1. Varies: Erythema, swelling, tenderness, warmth, fevers/chills (systemic symptoms), lymphangitis, edema, induration (hardening); may have a sharp demarcation
2. Break in skin
   Edema
   skin conditions
   immunosuppression
   procedures
3. Lower extremities
   Face
   Places of skin breakdown

Question 3

Common Bugs of Cellulitis

1. Gram +
2. Human bites (gram -)
3. Cat bites (gram -)
4. Dog Bites (gram -)

Answer 3

1. Gram +: Group A Strep, other hemolytic Strep, S. aureus (MRSA and MSSA)
2. Eikenella corrodens
3. Pasteurella multocida
4. Capnocytophaga canimorsus

Question 4

Gram stain appearance of

1. Strep
2. Staph

Answer 4

1. Gram + cocci in chains

2. Gram + cocci in clusters

Question 5

Differential Diagnosis for Cellulitis (3 main groups)

Answer 5

1. vascular disorders (thrombophlebitis, lymphedema)
2. Dermatologic disorders (contact dermatitis, drug rxns, insect stings/bites, urticaria)
3. Immunologic (gouty arthritis, Lupus, sarcoid)

Question 6

1. Define Purulent Cellulitis
2. Define Non-purulent Cellulitis
3. What causes purulent?
4. What causes non-purulent?

Answer 6

1. cellulitis associated with purulent drainage (abscess) or exudate in abscence of drainable abscess
2. cellulitis with no purulent drainage, exudate, or abscess
3. Staph (MRSA)
4. Strep species and Staph (MSSA)

Question 7

1. Where does purulent material drain from an abscess?

2. What does abscess feel like?

Answer 7

1. central area

2. fluctuant, moves

Question 8

Purulent Cellulitis

1. Abscess management
2. No drainable abscess

Answer 8

1. incise and drain w/ gram stain and culture;
   Need to give antibiotics
2. still need to cover CA-MRSA

Question 9

Non-Purulent Cellulitis

1. What do you need to cover w/ Abx?
2. Specific Abx for MSSA and Strep
3. Specific Abx for CA-MRSA and Strep

Answer 9

1. cover Strep and staph species (MRSA coverage not necessary)
2. Beta-lactam (cephalexin, dicloxacillin)
3. Clinda, Linezolid, bactrim, or doxy + beta-lactam

Question 10

How should joint infections be treated?

Answer 10

Aggressively; can have long lasting damage

Question 11

Complications of Cellulitis (3)

Answer 11

1. Sepsis
2. Toxic Shock Syndrome (both Staph and Strep can cause)
3. Necrotizing Fasciitis

Question 12

Risk Factors of Staph Toxic Shock Syndrome (9)

Answer 12

Menses, women, wound infections, mastitis, sinusitis, osteo, burns, lesions, arthritis

Question 13

Staph Toxic Shock Syndrome Presentation

1. Systemic manifestations
2. Blood Cultures
3. Skin Manifestations (2)
4. Multi-organ involvement

Answer 13

1. fever, hypotension
2. usually negative
3. diffuse fine macular erythema; desquamation (often of palms/soles)
4. N/V; diarrhea; thrombocytopenia, delirium, transaminitis; mucosal hemorrhage/hyperemia

Question 14

Staph TSS

1. What causes disease
2. Medical Management
3. Surgical Management

Answer 14

1. TSS toxin-1 (TSST-1) acting as a super Ag which activates a large number of T cells –> massive cytokine production and release
2. Supportive: fluids, vasopressor support; Abx
3. removal of any foreign body

Question 15

Strep TSS

1. Risk Factors
2. Pathogenesis

Answer 15

1. Surgery, injuries, trauma

2. Group A Strep creates exotoxins that act as superantigens (pyrogenis exotoxin A and B: SPEA and SPEB)

Question 16

Strep TSS Presentation

1. Systemic Manifestations
2. Skin
3. Other symptoms
4. Blood Cultures

Answer 16

1. fever or hypothermia, hypotension
2. swelling, erythema, skin sloughing; localized pain
3. altered mental state, renal dysfunction, DIC, ARDS
4. Positive Blood Culture in 50% of cases

Question 17

Strep TSS Treatment

1. Medical
2. Surgical

Answer 17

1. supportive; Abx

2. removal of any foreign body

Question 18

Necrotizing Fasciitis

1. Define
2. What bacteria are in Type I?
3. When does Type I occur
4. What bacteria are in Type II?

Answer 18

1. deep seated infection of subcutaneous tissue with destruction of fascia and fat
2. poly-microbial: aerobic/anaerobic; at least 1 or 2 staph/strep species
3. post surgery/ wound infection; Fournier’s gangrene (perineal area)
4. GAS or MRSA; mono-microbial

Question 19

Necrotizing Fasciitis- Clinical Presentations

1. Pain
2. How quickly does it progress?
3. Skin: initially
4. Skin: what does it progress to?
5. Systemic

Answer 19

1. out of proportion to how the skin looks; doesn’t usually look that bad
2. rapidly evolving
3. initially: minimal, slight erythema
4. may become dark, bullae/vesicles, signs of necrosis/gangrene
5. Fever, hypotension

Question 20

Necrotizing Fasciitis- Management

1. Surgery
2. Medical

Answer 20

1. early intervention is critical; all necrotic material must be removed
2. Empiric Abx: need to cover staph, strep, anaerobes, gram negatices (Vanco, zosyn, clindamycin)

Question 21

Impetigo

1. Define
2. Common presentation
3. Which microorganisms cause it?
4. Diagnosis
5. Treatment

Answer 21

1. superficial bacterial infection that is contagious
2. kids, on the face, sites of mild trauma
3. Group A strep; S. aureus; can be polymicrobial
4. clinical
5. Topical and/or systemic antibiotics: should cover strep and staph

Question 22

Bite wounds

1. Mono or poly microbial?
2. What is commonly present? (3)
3. What other species is common in cat bites?
4. What other species is common in dog bites?

Answer 22

1. poly-microbial
2. staph, strep, anaerobes
3. pasteurella species
4. capnocytophaga canimorsus (can cause rapid severe sepsis, esp in asplenic pts)

Question 23

Soft Tissue infections due to animal bites: Management

1. Wound Care
2. When is Abx prophylaxis recommended?
3. Abx treatment (oral and alternatives)

Answer 23

1. Irrigation, evaluate for closure
2. Deep puncture wounds, severe or crush injuries, hand wounds or close to bone/joint, wounds requiring closure, immunocompromised
3. Oral: amoxicillin-clavulanate;
   Alternatives: bactrim or doxycycline + flagyl or clindamycin

Question 24

Vibrio Vulnificus

1. Gram Stain
2. What kind of food is it associated with?
3. Who is at greater risk for infection?
4. Pathogenesis

Answer 24

1. negative
2. shellfish
3. alcoholics, hematochromatosis
4. toxin and capsule give virulence; dependent on Fe

Question 25

Vibrio Vulnificus | 1. How does it present?

Answer 25

1. mild cellulitis; usually on hands/legs, can develop severe myositis/fasciitis

Question 26

Pseudomonas causes skin infections in what situations (5)

Answer 26

1. after burns (common in burn sites, high mortality if it becomes bacteremic) 2. Trauma 3. skin grafts 4. Cellulitis in neutropenic pts 5. Folliculitis

Question 27

How does Pseudomonas present on the skin when it is already in the blood?

Answer 27

initial small area of edema painless nodules with ulceration, necrosis, or hemorrhage almost abscess-like

Question 28

Herpes Zoster (varicella) 1. What happens? 2. Presentation

Answer 28

1. reactivation of endogenous latent Varicella infection within the sensory ganglia 2. Painful, unilateral vesicular eruption (occurs after pain), dermatomal distribution, erythematous papules --> group into vesicles or bullae