- Recently there has been a dramatic increase in the frequency and severity of skin and soft-tissue infections (SSTIs) accompanied by the emergence of resistance to many of the antimicrobial agents commonly used to treat skin and soft-tissue infections in the past.
- There was a 29% increase in the total hospital admissions for these infections between 2000 and 2004.
- 6.3 million physician’s office visits per year are attributable to SSTIs.
- Between 1993 and 2005, annual emergency department visits for SSTIs increased from 1.2 million to 3.4 million patients.
- Some of this increased frequency is related to the emergence of community associated methicillin-resistant S. aureus (MRSA).
- Clinical evaluation of patients with SSTI aims to establish the cause and severity of infection and must take into account pathogen-specific and local antibiotic resistance patterns.
- When developing an adequate differential diagnosis and an appropriate index of suspicion for specific etiological agents it is essential to obtain a careful history that includes information about the patient’s immune status, geographical locale, travel history, recent trauma or surgery, previous antimicrobial therapy, lifestyle, hobbies, and animal exposure or bites.
- Recognition of the physical examination findings and understanding the anatomical relationships of skin and soft tissue are crucial for establishing the correct diagnosis.
- When information from history and physical are insufficient, biopsy or aspiration of tissue may be necessary, and radiographic procedures may be critical to determine the level of infection and the presence of gas, abscess or a necrotizing process.
- Surgical exploration or debridement is an important diagnostic as well as therapeutic procedure in patients with necrotizing infections or myonecrosis.
Impetigo and Ecthyma
- Gram stain and culture of the pus or exudates from skin lesions of impetigo and ecthyma are recommended to help identify whether Staphylococcus aureus and/or a β-hemolytic streptococcus is the cause (SR-M), but treatment without these studies is reasonable in typical cases (SR-M).
- Bullous and nonbullous impetigo can be treated with oral or topical antimicrobials, but oral therapy is recommended for patients with numerous lesions or in outbreaks affecting several people to help decrease transmission of infection. Treatment for ecthyma should be an oral antimicrobial.
- Treatment of bullous and nonbullous impetigo should be with either mupirocin or retapamulin bid for 5 days (SR-H).
- Oral therapy for ecthyma or impetigo should be a 7-day regimen with an agent active against S. aureus unless cultures yield streptococci alone (when oral penicillin is the recommended agent) (SR-H). Because S. aureus isolates from impetigo and ecthyma are usually methicillin-susceptible, dicloxacillin or cephalexin is recommended. When MRSA is suspected or confirmed, doxycycline, clindamycin, or sulfamethoxazole-trimethoprim (SMX-TMP) is recommended (SR-M).
- Systemic antimicrobials should be used for infections during outbreaks of post-streptococcal glomerulonephritis to help eliminate nephritogenic strains of Streptococcus pyogenes from the community (SR-M)
Purulent SSTIs (cutaneous abscesses, furuncles, carbuncles, and inflamed epidermoid cysts) (Figure 1)
- Gram stain and culture of pus from carbuncles and abscesses are recommended, but treatment without these studies is reasonable in typical cases (SR-M).
- Gram stain and culture of pus from inflamed epidermoid cysts are NOT recommended (SR-M).
- Incision and drainage is the recommended treatment for inflamed epidermoid cysts, carbuncles, abscesses and large furuncles
(See Fig. 1/Purulent/MILD) (SR-H).
- The decision to administer antibiotics directed against S. aureus as an adjunct to incision and drainage should be made based on the presence or absence of systemic inflammatory response syndrome (SIRS) such as temperature >38°C or <36°C, tachypnea >24 breaths/min, tachycardia >90 beats/min or white blood cell count (WBC) >12,000 or <400 cells/mm3 (See Fig. 1/Purulent/MODERATE) (SR-L). An antibiotic active against MRSA is recommended for patients with carbuncles or abscesses who have failed initial antibiotic treatment, have markedly impaired host defenses, or in patients with SIRS and hypotension (See Fig. 1/Purulent/SEVERE and Table 1) (SR-L). Tedizolid and dalbavancin are also effective treatments of SSTI including those caused by MRSA and were approved by the FDA after publication of the 2014 guideline.
Recurrent Skin Abscesses
- A recurrent abscess at a site of previous infection should prompt
a search for local causes such as a pilonidal cyst, hidradenitis suppurativa or foreign material (SR-M).
- Recurrent abscesses should be drained and cultured early in the
course of infection (SR-M).
- After obtaining cultures of recurrent abscess, treat with a 5- to 10-day course of an antibiotic active against the pathogen isolated (WR-L).
- Consider a 5-day decolonization regimen of intranasal mupirocin bid, daily chlorhexidine washes, and daily decontamination of personal items such as towels, sheets, and clothes for recurrent S. aureus infection (WR-L).
- Adult patients should be evaluated for neutrophil disorders if recurrent abscesses began in early childhood (SR-M).
Erysipelas and Cellulitis
- Cultures of blood or cutaneous aspirates, biopsies, or swabs are NOT routinely recommended (SR-M).
- Cultures of blood are recommended (SR-M), and cultures and microscopic examination of cutaneous aspirates, biopsies, or swabs should be considered in patients with malignancy on chemotherapy, neutropenia, severe cell-mediated immunodeficiency, immersion injuries, and animal bites (WR-M).
- Typical cases of cellulitis without systemic signs of infection should receive an antimicrobial agent that is active against streptococci (See Fig. 1/Nonpurulent/MILD) (SR-M). For cellulitis with systemic signs of infection (See Fig. 1/Nonpurulent/MODERATE) systemic antibiotics are indicated. Many clinicians could include coverage against methicillin-susceptible S. aureus (MSSA) (WR-L). For patients whose cellulitis is associated with penetrating trauma, evidence of MRSA infection elsewhere, nasal colonization with MRSA, injection drug use, or SIRS (See Fig. 1/Nonpurulent/SEVERE), vancomycin or another antimicrobial effective against both MRSA and streptococci is recommended (SR-M). In severely compromised patients as defined above (See Fig. 1/Nonpurulent/SEVERE) broad-spectrum antimicrobial coverage may be considered (WR-M). Vancomycin plus either piperacillin-tazobactam or imipenem/meropenem is recommended as a reasonable empiric regimen for severe infections (SR-M).
- The recommended duration of antimicrobial therapy is 5 days, but treatment should be extended if the infection has not improved within this time period (SR-H).
- Elevation of the affected area and treatment of predisposing factors, such as edema or underlying cutaneous disorders, are recommended (SR-M).
- In lower extremity cellulitis, clinicians should carefully examine the interdigital toe spaces because treating fissuring, scaling, or maceration may eradicate colonization with pathogens and reduce the incidence of recurrent infection (SR-M).
- Outpatient therapy is recommended for patients who do not have SIRS, altered mental status, or hemodynamic instability (See Fig. 1/Nonpurulent/MILD) (SR-M). Hospitalization is recommended if there is concern for a deeper or necrotizing infection, for patients with poor adherence to therapy, for infection in a severely immunocompromised patient or if outpatient treatment is failing (See Fig. 1/Nonpurulent/MODERATE or SEVERE) (SR-M).
Anti-inflammatory Agents for Cellulitis
- Systemic corticosteroids (eg, prednisone 40 mg daily for 7 days) could be considered in nondiabetic adult patients with cellulitis (WR-M).
- Identify and treat predisposing conditions such as edema, obesity, eczema, venous insufficiency, and toe web abnormalities (SR-M). These practices should be performed as part of routine patient care and certainly during the acute stage of cellulitis (SR-M).
- Administration of prophylactic antibiotics, such as oral penicillin or erythromycin bid for 4-52 weeks, or intramuscular benzathine penicillin every 2-4 weeks should be considered in patients who have 3-4 episodes of cellulitis per year despite attempts to treat or control predisposing factors (WR-M). This program should be continued so long as the predisposing factors persist (SR-M).