SSTIs

skin and soft tissue infections (SSTIs)

infections of the skin that may involve any or all layers of the skin, SQ tissue, muscle, or fascia

Erysipelas

Impetigo

Lymphangitis

Cellulitis

Necrotizing fascitis

Primary SSTIs

Diabetic foot infections

Pressure sores

Animal and human bite wounds

Burn wounds

Secondary SSTIs

GP organisms: MSSA, MRSA, S. pyogenes

SSTIs are primarily caused by what organisms?

1. Age (anybody)

2. Obesity

3. Poor hygiene

4. Diabetes

5. Dialysis

6. Immunocompromised

7. Prior injury: trauma, radiotherapy, surgery

8. Vascular insufficiency: lymphatic or venous

9. IV drug abuse

10. Trauma

Risk factors for SSTIs

CA-MRSA

SSTIs that occur in patients with no known risk factors for MRSA

true

- Clindamycin

- TMP-SMX

- Doxycycline or Minocycline

T/F: CA-MRSA is more likely to be sensitive to oral antimicrobials

1. individuals in close proximity to each other

2. IV drug users

3. Tattooing and piercings

4. Homelessness

5. HIV infection

6. MSM

CA-MRSA risk factors

Panton-Valentine Leukocidin (PVL)

Cytotoxin produced by CA-MRSA

true

T/F: HA-MRSA is less likely to produce Panton-Valentine Leukocidin (PVL) toxin

1. Indwelling catheter

2. Hemodialysis

3. Prolonged hospitalization

4. Prolonged antimicrobial use

5. ICU admission

HA-MRSA risk factors

Impetigo

- characterized as bullous or nonbullous

Contagious, superficial, purulent bacterial infection of the skin, which leaves a dry crust after eruption

S. pyogenes

S. aureus

Which organisms are responsible for causing impetigo?

Pruritis

Weakness

Fever

Diarrhea

Clinical presentation of impetigo

children

Impetigo is most common in ____ and usually affects the face followed by the extremities

summer (hot and humid weather conditions)

Impetigo is most prevalent in which season?

nonbullous

Most common form of impetigo

S. pyogenes

S. aureus

Which organisms cause nonbullous impetigo?

Nonbullous impetigo

Which kind of impetigo is characterized by small, fluid-filled vesicles that discharge to form dry, honey-crusted lesions?

Bullous impetigo

Which kind of impetigo is characterized by vesicles containing clear yellow fluid that discharge to form a thin, light brown crust?

neonates

Bullous impetigo mostly occurs in what patient population (what age)?

S. aureus

What is the causative organism of bullous impetigo?

When there are not several lesions and it does not involve the face.

When is topical therapy indicated for impetigo?

Mupirocin (first line) or Retapamulin applied topically BID x 5 days

Topical treatment for impetigo.

oral

Which type of therapy (oral or topical) for impetigo is recommended for patients presenting with multiple lesions and/or involving the face?

Cephalexin (first-line)

- Peds: 25 to 50 mg/kg/day divided every 6 to 8 hours

- Adult: 250 mg PO QID x 7 days

Dicloxacillin

- Peds: 6.25 to 12.5 mg/kg/dose every 6 hours

- Adult: 250 to 500 mg QID x 7 days

Recommended treatment for impetigo caused by S. aureus and GAS.

TMP-SMX (first-line alternative)

- Peds: 8 to 12 mg TMP/kg/day in divided doses every 12 hours for 7 days

- Adults: 1 to 2 double-strength tablets twice daily for 7 days

Clindamycin

- Peds: 20 mg/kg/day in divided doses every 8 hours for 7 days

- Adults: 300 mg 4 times daily or 450 mg 3 times daily for 7 days

Doxycycline (do not use in patients <8)

- Peds: ≤45 kg: Oral: 2 mg/kg/dose every 12 hours for 5 to 10 days; >45 kg: Oral: 100 mg twice daily for 5 to 10 days.

- Adults: 100 mg PO twice daily for 7 days

Recommended treatment for impetigo caused by CA-MRSA and/or for patients with a PCN allergy

Lymphangitis

Inflammation of the lymphatic channels

S. pyogenes

Causative organism of Lymphangitis

Red linear streaks, enlarged and tender lymph nodes, peripheral edema, pain, fever, chills, malaise, headache

Clinical presentation of lymphangitis

DOC: PCN G 1-2 million units IV Q4-6 hours x 48-72 hours then switch to PCN VK 500 mg PO Q6 hours

- Total days of therapy: 10 days

*If PCN allergy: Clindamycin 600 mg IV Q8 hours x 10 days

- start with IV; if patient improves, switch to PO

Recommendation of therapy for lymphangitis

Immobilization and elevation of the affected extremity with warm, moist compresses every 2-4 hours

Nonpharmacological treatment of lymphangitis

Abscess

Furuncle

Carbuncle

List some purulent SSTIs

Patients with purulent infection and NO systemic signs of infection

- localized signs of infection

Purulent SSTI mild infection

Patients with purulent infection with systemic signs of infection

- at least 1 SIRS criteria

Purulent SSTI moderate infection

Patients who have failed incision and drainage plus antibiotics OR those meeting SIRS criteria (≥2) OR those who are immunocompromised

Purulent SSTI severe infection

Temperature > 38°C or < 36°C (>100.4°F or <96.8°F)

HR > 90

RR > 24

WBC > 12,000 or < 4,000

SIRS criteria

true; gold-standard

- may see recurrent infection if I&D is not done

T/F: I&D and C&S should be for mild, moderate, and severe purulent SSTIs (abscess, furuncle, carbuncle)

SMX-TMP (first-line): 1 to 2 double-strength tablets twice daily for ≥5 days.

Doxycycline 100 mg PO BID x 5 days.

Empiric treatment for moderate, purulent SSTIs.

Vancomycin 15 mg/kg Q12 hours.

Daptomycin 4-6 mg/kg IV once daily.

Linezolid 600 mg IV Q12 hours.

Telavancin 10 mg/kg IV once daily.

Ceftaroline 600 mg IV Q12 hours.

Empiric treatment for severe, purulent SSTIs

SMX-TMP 1 to 2 double-strength tablets twice daily for ≥5 days.

- if a patient has an allergy to sulfa, then use Doxycycline

Definitive treatment for moderate, purulent SSTIs caused by MRSA

Cephalexin (first-line): 500 mg PO QID

Dicloxacillin 500 mg PO QID

Definitive treatment for moderate, purulent SSTIs caused by MSSA

Same as empiric therapy

Vancomycin 15 mg/kg Q12 hours x 5-7 days.

Daptomycin 4-6 mg/kg IV once daily x 5-7 days.

Linezolid 600 mg IV Q12 hours x 5-7 days.

Telavancin 10 mg/kg IV once daily x 5-7 days.

Ceftaroline 600 mg IV Q12 hours x 5-7 days.

Definitive treatment for severe, purulent SSTIs caused by MRSA

Nafcillin 1.5-2 g IV Q4 hours

Cefazolin 1-2 g IV Q8 hours

Clindamycin 600 mg IV every 8 hours

- only if PCN allergy

Definitive treatment for severe, purulent SSTIs caused by MSSA

Folliculitis

Inflammation of the hair follicle due to physical injury, chemical irritation, or infection

Stye

Infection occurring at the base of the eyelid

- type of folliculitis

S. aureus

P. aeruginosa

Most common causative organisms of folliculitis

Small, pruritic, erythematous papules

- systemic signs are uncommon; use topical treatment

Clinical presentation of folliculitis

Mupirocin topically TID x 5-7 days

Clindamycin topically BID x 7-10 days

Benzoyl peroxide topically once daily

Topical therapy for folliculitis

Furuncles

Painful, firm, fluctuant abscess or boil originating from an infected hair follicle

- (+/-) necrotic centers characteristic of spider bite

S. aureus

Causative organism of furuncles

Small, red, tender nodule that becomes painful and pustular

- commonly develops on the face, neck, axilla, and buttocks

Clinical presentation of furuncles

Carbuncles

Coalescent furuncles extending to the subcutaneous tissue that are large and painful

- can be associated with fever, chills, malaise, and bacteremia

diabetic patients and form on the back of the neck

Carbuncles commonly occur in _____ patients and form where?

Patients with nonpurulent infection and no systemic signs of infection

- localized infection

Nonpurulent SSTI mild infection

Patients with nonpurulent infection with systemic signs of infection

- at least one SIRS criterion

Nonpurulent SSTI moderate infection

Patients who have failed oral abx OR those with systemic signs (≥2 SIRS criteria) of infection OR immunocompromised OR with deeper tissue involvement (bullae, skin sloughing, hypotension, organ dysfunction)

Nonpurulent SSTI severe infection

Cellulitis

Erysipelas

Necrotizing infection

Types of nonpurulent SSTIs

Oral

- PenVK 500 mg Q6 hours

- Cephalexin 500 mg QID

- Cefadroxil 1 g QD or 500 mg BID

- Dicloxacillin 500 mg QID

- Clindamycin 300 mg QID or 450 mg TID

Empiric treatment for mild nonpurulent SSTIs

IV

- PCN G 2-4 million units Q4-6 hours

- Cefazolin 1-2 g Q8 hours

- Ceftriaxone 1-2 g QD

- Clindamycin 600-900 mg Q8 hours

Empiric treatment for moderate nonpurulent SSTIs

- Urgent surgical consult/debridement

- Empiric: Vancomycin 15 mg/kg Q12 hours + Pip/Tazo 4.5 g Q8 hours

Empiric treatment for severe nonpurulent SSTIs

Penicillin 4 million units IV Q4 hours

PLUS

Clindamycin 600-900 mg IV Q8 hours

Definitive treatment for necrotizing infection (severe) caused by S. pyogenes

Penicillin 4 million units IV Q4 hours

PLUS

Clindamycin 600-900 mg IV Q8 hours

Definitive treatment for necrotizing infection (severe) caused by Clostridial spp.

Doxycycline 100 mg IV BID

PLUS

3rd gen Cephalosporin (IV):

- Ceftriaxone 1-2 g QD

- Cefotaxime 2 g Q6 hours

- Ceftazidime 2 g Q8 hours

Definitive treatment for necrotizing infection (severe) caused by Vibrio vulnificus

Doxycycline 100 mg IV BID

PLUS

Ciprofloxacin 400 mg IV Q12 hours or Ceftriaxone 1-2 g QD

Definitive treatment for necrotizing infection (severe) caused by Aeromonas hydrophila

Vancomycin 15 mg/kg Q12 hours

PLUS

Pip/Tazo 4.5 g Q8 hours

Polymicrobial definitive treatment for necrotizing infection (severe)

Cellulitis

Acute, inflammatory infection of superficial and deep skin (dermis, superficial fascia)

S. pyogenes

S. aureus

Causative organisms for cellulitis

Erythema and edema of the skin that is not elevated with poorly demarcated borders, tenderness/pain, warm to the touch, w/o purulent drainage

Clinical presentation of cellulitis

Erysipelas

Infection of the superficial layers of the skin and lymphatics

- aka "St. Anthony's Fire"

S. pyogenes (S. aureus less common)

Causative organisms of erysipelas

Burning, painful lesion, bright red, edematous, indurated appearance, defined margins, warm to the touch

- legs and feet most affected

- low-grade fever, flu-like illness, leukocytosis

Clinical presentation of erysipelas

Penicillin VK 500 mg Q6 hours or Cephalexin 500 mg QID for 5-7 days

Empiric treatment for a mild infection of cellulitis or erysipelas

Dicloxacillin 500 mg QIDx 5-7 days

- PCN allergy: Clindamycin 300 mg QID or 450 mg TID

Definitive treatment of a mild infection of cellulitis or erysipelas caused by MSSA

SMX-TMP 1-2 DS tabs PO BID,

Doxycycline 100 mg PO BID,

Minocycline 200 mg PO LD, then 100 mg Q12h, or

Clindamycin 300 mg QID or 450 mg TID

Definitive treatment of a mild infection of cellulitis or erysipelas caused by MRSA

PCN G 2-4 million units IV Q4-6 hours x5-7 days

Empiric treatment of a moderate infection of cellulitis or erysipelas

Cefazolin 1-2 g Q8 hours or Ceftriaxone 1-2 g QD x5-7 days

- PCN allergy: Clindamycin 600-900 mg Q8 hours x 5-7 days

Definitive treatment of a moderate infection of cellulitis or erysipelas caused by MSSA

Choose one:

Vancomycin 15 mg/kg IV Q12 hours

Daptomycin 4 to 6 mg/kg IV once daily

Linezolid 600 mg IV Q12 hours

Telavancin 10 mg/kg IV once daily

Ceftaroline 600 mg IV Q12 hours

Definitive treatment of a moderate infection of cellulitis or erysipelas caused by MRSA

Vancomycin 15 mg/kg IV Q12 hours PLUS Pip/Tazo 4.5 g Q8 hours x 5-7 days

- Alt: Vancomycin + Primaxin 500 mg Q6 hours or Meropenem 1 g Q8 hours x 5-7 days

Empiric treatment for severe infections of cellulitis or erysipelas

Necrotizing fasciitis

Highly aggressive, very fast-spreading, serious, life-threatening infection of the subcutaneous tissue

S. pyogenes (most common)

S. aureus (MSSA or MRSA)

Vibrio vulnificus

A. hydrophila

Peptostreptococcus

Polymicrobial

Causative organisms for necrotizing fasciitis

Infection site reveals edema, inflammation, discoloration, possible gangrene, crepitus (gas in the tissues), skin necrosis, bullous lesions, and wooden hard induration of the subcutaneous tissue

- mostly involves limbs and lower extremities, but can occur anywhere

- pain, AMS, fever, chills, leukocytosis, lethargy

Clinical presentation of necrotizing fasciitis

Type I

Which type of necrotizing fasciitis is described below?

- Generally occurs after trauma or surgery

- Organisms: anaerobes (Bacteriodes, Peptostreptococcus), facultative aerobes (streptococci, enterbacteriaceae)

- Less skin destruction, slower progression: 3-5 days

Type II "flesh-eating disease"

Which type of necrotizing fasciitis is described below?

- Organisms: S. pyogenes; referred to as streptococcal gangrene

- Rapid skin/subcutaneous tissue desctruction (24-72 hours), local pain, systemic toxicity, early onset of shock/organ failure

Type III: Clostridial myonecrosis "gas gangrene"

Which type of necrotizing fasciitis is described below?

- Organisms: Clostridium perfringens

- Infection of skeletal muscle causing gas production and muscle necrosis

- Progression 1-6 hours

Choose one:

- Vancomycin 15 mg/kg IV Q12 hours

- Daptomycin 4 to 6 mg/kg IV once daily

- Linezolid 600 mg IV Q12 hours

PLUS (choose one):

- Pip/Tazo4.5 g Q8H

- Ertapenem 1 g QD, Primaxin 1 g Q6-8H, or Meropenem 1 g Q8H

- Ceftriaxone 1-2 g QD PLUS Metronidazole 500 mg Q6H

- Ciprofloxacin 400 mg Q12H or Levofloxacin 750 mg QD PLUS Metronidazole 500 mg Q6H

Empiric treatment of necrotizing fasciitis

Penicillin 4 million units Q4 hours PLUS Clindamycin 600 to 900 mg Q8 hours

Definitive treatment for necrotizing fasciitis caused by S. pyogenes

Penicillin 4 million units Q4 hours PLUS Clindamycin 600 to 900 mg Q8 hours

Definitive treatment for necrotizing fasciitis caused by Clostridial spp.

Doxycycline 100 mg IV BID

PLUS

3rd generation cephalosporin (choose one):

- Ceftriaxone 1-2 g QD

- Cefotaxime 2 g Q6H

- Ceftazidime 2 g Q8H

Definitive treatment for necrotizing fasciitis caused by V. vulnificus

Doxycycline 100 mg IV BID PLUS Ciprofloxacin 400 mg Q12H OR Ceftriaxone 1-2 g QD

Definitive treatment for necrotizing fasciitis caused by A. hydrophila

20%

Diabetic foot infections (DFI) account for ___% of all hospitalizations in diabetics.

- Can progress to: amputation and osteomyelitis

Deep abscesses

Cellulitis of the dorsum

Mal perforans ulcers

Types of DFIs

Edema, erythema, tenderness, pain, induration, and purulent secretions

- Foul-smelling odor, discolored granulation tissue, and mildly elevated or normal temp

Clinical presentation of DFI

No systemic or local symptoms or signs of infection

PEDIS Grade 1 for classifying DFIs

- IDSA: uninfected

At least 2 of the following present and no other cause of inflammatory response of the skin (e.g., trauma, gout, thrombosis, fracture, venous stasis):

- local swelling or induration

- erythema around the ulder must be > 0.5 cm to < 2 cm

- local tenderness or pain

- local increased warmth

- purulent discharge

PEDIS Grade 2 for classifying DFIs

- IDSA: mild infection

Infection with no systemic manifestations and involving:

- erythema ≥2 cm from the wound margin and/or

- tissue deeper than skin and SQ tissue (tendon, muscle, joint, and bone)

PEDIS Grade 3 for classifying DFIs

- IDSA: moderate infection

Any foot infection with ≥ 2 of the following SIRS criteria:

- Temperature > 38°C or < 36°C (>100.4°F or <96.8°F)

- HR > 90

- RR > 24

- WBC > 12,000 or < 4,000 or ≥10% bands

PEDIS Grade 4 for classifying DFIs

- IDSA: severe infection

Bed rest, leg elevation, proper glycemic control, wound drainage, wound dressing changes 2-3 times daily, avoidance of weight-bearing activities

Nonpharmacological treatment of DFIs

Suspected MSSA, Streptococcus spp.:

- Augmentin 875 mg BID

- Cephalexin 250 to 500 mg QID

- Clindamycin 300 to 450 mg Q6-8H

- Dicloxacillin 250 to 500 mg QID

- Levofloxacin 500 mg QD

Suspected MRSA:

- Doxycycline 100 mg BID

- SMX/TMP 1-2 DS tabs PO BID

Treatment of Mild DFIs

- topical or oral therapy for 1-2 weeks

- Unasyn 3 g IV Q6H

- Cefoxitin 1-2 g IV Q6-8H

- Ceftriaxone 1-2 g QD

- Ciprofloxacin 400 mg IV Q12H + Clindamycin 300-450 mg Q6-8H

- Ertapenem 1 g QD

- Primaxin 500 mg Q6H

- Levofloxacin 750 mg IV Q24 hours + Clindamycin 300-450 mg Q6-8H

- Moxifloxacin 400 mg IV/PO QD

- Tigecycline 100 mg IV LD, then 50 mg IV Q12H

Treatment of moderate DFIs when there's suspected MSSA, Streptococcus, Enterobacteriaceae, and/or obligate anaerobes

- PO therapy or initial parenteral followed by oral therapy for 1-3 weeks