SSTIs Flashcards
Purulent SSTIs
- Impetigo
- Cutaneous abcesses
- Inflamed epidermoid cysts
- Furuncles
- Carbuncles
What is Impetigo?
- Highly contagious infection of epidermis
- Typically transmitted through direct contact
- Occurs most commonly in children
- Most frequently affects face and extremities
What are the two types of Impetigo?
Nonbullous (~70% of cases)
Bullous
What are the predisposing factors of Impetigo?
- Group A Strep skin colonization or S. aureus nasal colonization.
- Hot, humid summer weather
- Areas with poor hygiene and in crowded living conditions
- Minor trauma (insect bite, abrasion)
What is Nonbullous Impetigo?
- Caused by: Strep pyogenes (Group A) or Staph aureus
- Small, fluid filled vesicles → pustules → pustules rupture → golden yellow crusts over an erythematous base
What is Bullous Impetigo?
- Caused by: Staphylococcus aureus
- Vesicles → bullae with clear, yellow fluid → bullae rupture, forming thin, light brown crusts
- Usually affects neonates and children < 5 yo
Ecthyma
- Ulcerative form of impetigo causing painful fluid- or pus-filled sores; heals with scarring
- Requires abx tx
Topical Treatment of Impetigo
- Topical therapy is as effective as systemic therapy
- Mupirocin or retapamulin applied to lesions
Duration of Topical Treatment of Impetigo
5 days
Systemic Treatment of Impetigo (suspicion or confirmation of MRSA)
- Clindamycin
- Doxycycline
- TMP/SMX
Systemic Treatment of Impetigo (no suspicion of MRSA)
- Dicloxacillin
- Cephalexin
Duration of Systemic Treatment of Impetigo
7 days
What is Folliculitis?
- Pyoderma located within hair follicles
- Small (<5mm), erythematous (sometimes pruritic) papules usually covered by central pustule
- Develops in areas of friction and perspiration (armpits, groin, etc.)
What are the causative organisms of Folliculitis?
- S. aureus (most common)
- P. aeruginosa (swimming pools, hot tubs, whirlpools)
- Candida spp (prolonged antibiotics or corticosteroids)
What is the treatment for Folliculitis?
- Saline compresses (promotes drainage)
- Topical therapy with antibacterials or antifungals sufficient
What are Furuncles (Boils)?
- Deep inflammatory nodule that typically develops from preceding folliculitis.
- Lesions often rupture and drain spontaneously
What is the treatment for Furuncles?
Application of moist heat to promote drainage
What are Carbuncles?
- When infection extends to involve several adjacent follicles producing a coalescing inflammatory mass with pus draining from multiple follicular orifices.
- Progression from furuncles
- Typically found at nape of neck, face, armpits, buttocks
- Fever and malaise usually present
What is the causative organism of Furuncles and Carbuncles?
S. aureus
What are the predisposing factors for Furuncles and Carbuncles?
- Diabetes, obesity
- Inadequate personal hygiene
- Close contact with others with furuncles
- Anterior nares colonization with S. aureus (recurrent cases)
What is the treatment for Furuncles and Carbuncles?
- Incision and drainage (I&D)
- Systemic antibiotics rarely required unless fever or multiple furuncles/carbuncles
Causative Organism of Cutaneous Abcesses and Inflamed Epidermoid Cysts
S. aureus
Treatment of Cutaneous Abcesses and Inflamed Epidermoid Cysts
- Incision and evacuation of pus and debris
- Systemic antibiotics usually NOT recommended
When to use systemic abx for purulent SSTI
- Systemic signs of infection (fever, etc.)
- Multiple abcesses
- Lack of response to I & D
- Immunocompromised
Duration of Systemic Abx Therapy for Purulent SSTI
5 days
When is MRSA coverage warranted for purulent SSTI?
- Long-term care facility
- IV drug abuse
- HIV
- MSM
- Incarceration
- Military
- Native American
- Sharing razors or sports equipment
- History of MRSA infection/colonization
- Current MRSA infection elsewhere
- Failed initial abx therapy
- Penetrating trauma
- Markedly impaired host defenses
- Severe infection with systemic sxs and/or hypotension
Duration of Therapy for Purulent SSTI if concern for MRSA
5-7 days
PO Antibiotics for MSSA Purulent SSTI
- Dicloxacillin
- Cephalexin
IV Antibiotics for MSSA Purulent SSTI
- Nafcillin/Oxacillin
- Cefazolin
- Clindamycin (if pt has beta-lactam allergy)
PO Antibiotic Therapy for MRSA Purulent SSTI
- Doxycycline
- TMP/SMX
- Clindamycin (need to do D-test first to check susceptibility)
IV Antibiotics for MRSA Purulent SSTI
- Vancomycin (DOC)
- Linezolid
- Ceftaroline
- Daptomycin
- Oritavancin (preferred for outpatient)
- Dalbavancin (preferred for outpatient)
- Tedizolid
Treatment of Recurrent S. aureus SSTI
- Nasal decolonization: Mupirocin 2% intranasal x 5-10 days
- Topical decolonization: Chlorhexidine or bleach bath
What is Cellulitis?
- Acute, spreading infection of skin that involves epidermis and dermis.
- Local tenderness/pain, swelling, warmth, erythema
What is the location of Cellulitis?
Commonly on lower legs
What are the systemic manifestations of Cellulitis?
Fever, tachycardia, confusion, hypotension, leukocytosis
Erysipelas
Superficial form of cellulitis with clearly defined borders of inflammation
What are the predisposing factors for Cellulitis?
- Previous trauma (laceration, puncture wound)
- Conditions that cause skin to be more fragile or local host defenses less effective (obesity, diabetes, previous cutaneous damage, edema (from venous insufficiency or lymphatic obstruction), surgical procedures, eczema)
Common Pathogens Causing Cellulitis
- S. pyogenes (Group A) - most common
- S. aureus
How to Differentiate Between Cellulitis Caused by S. pyogenes or S. aurues
S. aureus infection usually has pus, purulence, or abcess
S. pyogenes infection does not
Diagnosis of Cellulitis
- Done by physical exam
- Routine diagnostic testing NOT recommended
Symptoms of Mild Cellulitis
- No purulence
- No systemic sxs, AMS, or hemodynamic instability
Treatment of Mild Cellulitis
- Outpatient tx
- Penicillin
- Augmentin
- Cephalexin
- Clindmycin (if beta-lactam allergy)
Signs/Symptoms of Mederate-Severe Cellulitis
- Deeper infection
- Poor adherence
- Systemic sxs
- Failed outpatient therapy
- Immunocompromised
Treatment of Moderate-Severe Cellulitis
- Inpatient tx
- Penicillin IV
- Cefazolin or ceftriaxone
- Clindamycin (if beta-lactam allergy)
Duration of Cellulitis Treatment (regardless of severity)
5 days
When is MRSA coverage indicated for cellulitis?
- Penetrating trauma
- Evidence of MRSA infection elsewhere
- Nasal colonization with MRSA
- Injection drug use
- Purulent drainage
- Severe infection (necrotizing)
PO Treatment for MRSA Cellulitis
- TMP/SMX
- Doxycycline
- Clindamycin
IV treatment for MRSA Cellulitis
- Vancomycin (DOC)
- Linezolid
- Daptomycin
- Ceftaroline
- Tigecycline
- Telavancin
- Tedizolid
- Oritavancin
- Dalbavancin
Cellulitis Treatment if Coverage for Strep and MRSA Needed
- Clindamycin
- TMP/SMX + Beta-Lactam
- Doxycycline + Beta-Lactam
Non-Medication therapy for Cellulitis
Elevation of affected area
Adjunctive Treatment for Cellulitis
Systemic corticosteroids x 7 days in non-diabetic adults
Recurrent Cellulitis
- 2+ discrete SSTIs over a 6 month period
- 3-4 SSTIs/year