Skin, Soft Tissue, & Bone Infections

Question 1

Etiology of Impetigo

Answer 1

S. pyogenes (GAS) & S. aureus (usually MSSA)

Question 2

Presentation of Impetigo

Answer 2

• Vesicles develop & progress into either pustules or bullae
• Pustules/bullae rupture & dry into brown or golden-yellow crusts
• pruritus is common, but systemic symptoms are rare

Question 3

Impetigo Treatment

Answer 3

• Dicloxacillin 250mg PO QID x 7 days
• Keflex 250mg PO QID x 7 days –> Children 25-50mg/kg/day PO in 3-4 divided doses
• Mupirocin or retapamulin (Altabax) ointment applied topically BID x 5 days

Question 4

MRSA suspected in Impetigo

Answer 4

If MRSA is suspected based on hx or colonization, consider Bactrim DS, Cleocin, or doxycycline (avoid in pregnancy & children < 8 yrs)

Question 5

Erysipelas Etiology

Answer 5

Typically S. pyogenes (GAS)

Question 6

Presentation of Erysipelas

Answer 6

• most often on lower extremities
• Erythematous, edematous lesion w/ a raised border
• Burning pain in the infected area, mild fever, flu-like symptoms may occur prior to lesion appearance

Question 7

Treatment of Erysipelas

Answer 7

-Group A Strep - Natural PCN adequate (7-10 day course)

Severe Infection: Aqueous crystalline PCN G 1-2 million units IV Q4-6

Question 8

Etiology of Cellulitis

Answer 8

Most often S. pyogenes (GAS) & S. aureus

Question 9

Presentation of Cellulitis

Answer 9

• Non-elevated erythematous & edematous skin lesion (often hot & painful)
• Systemic symptoms can occur (flu-like symptoms, hypotension, altered mental status)

Question 10

Treatment of uncomplicated cellulitis

Answer 10

• Initial oral therapy 5 days is recommended for uncomplicated cellulitis
• S. pyogenes coverage is often sufficient: PCN VK, Amoxil
• Initial coverage of S. aureus is often used: Keflex, dicloxacillin, Cleocin
• MRSA coverage may be indicated w/ penetrating trauma or purulence: Bactrim, Vibramycin

Question 11

Treatment of complicated cellulitis

Answer 11

• Hospitalization/IV therapy indicated if SIRS criteria, altered mental status, hemodynamic instability, or outpatient treatment failure
• Vanc is most commonly used (goal trough typically 10-15mcg/ml)
• Inpatient alternatives for MRSA = ceftaroline, linezolid, daptomycin, & telavancin
• Cefazolin or nafcillin/oxacillin may be used in less severe, non-purulent infections

Question 12

Causes of DFIs

Answer 12

Ulceration, minor trauma, or poor nail care

Question 13

Etiology of DFIs

Answer 13

• Severe infections are often polymicrobial (gram +, gram -, anaerobes)
• Pseudomonas is rare, but has been observed
• Foul odor is suggestive of anaerobic involvement

Question 14

Treatment of Mild DFIs

Answer 14

Oral therapy for initial duration of 1-2 weeks:

• Augmentin 875/125mg BID
• Keflex 250-500mg Q6
• Dicloxacillin 250-500mg Q6
• Levaquin 500-750mg QD
• Cleocin 300-600mg Q6-8 (often has activity against CA-MRSA)
• Doxycycline 100-200mg BID (if CA-MRSA suspected)
• Bactrim 160/800mg Q12 (if CA-MRSA suspected; DOC)

Question 15

Diagnosis of Osteomyelitis

Answer 15

• Diagnosed by MRI if available
• Bone biopsy required for definitive organism identification
• Pathogen from a previously undrained wound culture can be useful

Question 16

Treatment of Osteomyelitis

Answer 16

Adults: nafcillin/oxacillin 2g IV Q4 or cefazolin 2g IV Q8 –> IV drug users and/or vascular insufficiency: Cipro 750mg PO BID

Question 17

Etiology of Bite Wounds

Answer 17

Dogs: Pasteurella canis
Cats: Pasteurella multocida, Pasteurella tularensis, Bartonella henselae
Humans: Eikenella corrodens

Question 18

Treatment of Bite Wounds

Answer 18

DOC: Augmentin 875/125mg PO BID –> 3-5 days prophylactic course is recommended for cat & human bites ( dog bites may not require antibiotic therapy unless patient immunocompromised)
- 7-14 day course for established infection

Question 19

Assessments for patients w/ Bite wounds

Answer 19

• assess history of tetanus immunization

- assess for possibility of rabies