A Closer Look at Skin and Soft Tissue Infections

Straying From the Guidelines

Guidelines for management of skin and soft tissue infections (SSTIs) were published in 2014.^[1] Nevertheless, management of SSTIs is variable, probably driven by the fact that culture results are often unavailable to direct clinical decision-making. Treatment variability results in inappropriate (prolonged duration or unnecessary broad-spectrum) antibiotic use, highlighting the need for antibiotic stewardship. Consequently, management of SSTIs is one area where more research has identified easy targets for improvement. This review describes two such studies.

Cotrimoxazole Monotherapy?

The first, a systematic review conducted by Bowen and colleagues,^[2] sought to answer the question: For which SSTIs, including SSTIs with group A streptococci (GAS), can we use sulfamethoxazole-trimethoprim (SMX) monotherapy? This question has important implications, because SMX monotherapy allows for more narrow-spectrum antibiotic use, improved adherence, and possibly fewer adverse drug events. Moreover, there has been a longstanding belief that SMX is ineffective for SSTI caused by GAS.

After identifying 196 potential studies, 10 randomized controlled trials (RCTs) and five observational studies underwent full-text review. The largest RCT of impetigo, with 90% of isolates cultured as GAS, found a nonsignificant difference in treatment success with 3-5 days of SMX versus benzathine penicillin. Therefore, the study authors recommended a short course of SMX as the treatment of choice for impetigo (when the clinical situation dictates systemic therapy). This systematic review also highlights newer RCTs, finding a benefit of adding SMX to incision and drainage for cutaneous abscesses versus incision and drainage alone. The study found strong evidence to support the use of SMX monotherapy for SSTIs, including impetigo caused by GAS, purulent SSTIs, and cutaneous abscesses (coupled with incision and drainage). The study authors also reiterated that beta-lactams alone are the treatment of choice for nonpurulent cellulitis, because coverage for methicillin-resistant Staphylococcus aureus (MRSA) coverage provides no additional benefit.

SSTIs in the Emergency Department

The second study, conducted by Kamath and colleagues,^[3] was a retrospective analysis of 240 patients diagnosed with purulent or nonpurulent SSTIs in a large Veterans Administration hospital emergency department (ED). They found that most SSTI management in that setting was not consistent with guideline recommendations. Patients seen in the ED for SSTIs were often admitted to the hospital inappropriately (20%) or discharged from the ED inappropriately (34%). Treatment of nonpurulent cellulitis was guideline adherent only 30% of the time; most patients received some agent covering community-associated MRSA.

Compliance with guidelines improved slightly with the management of purulent SSTIs (44% compliance). Most patients (88%) received antibiotics for mild cutaneous abscesses in addition to incision and drainage. Although newer data suggest a possible benefit of antibiotics in addition to incision and drainage for mild cutaneous abscesses,^[4] current guidelines recommend incision and drainage alone. Finally, the investigators evaluated diagnostic testing and found that from 29% of patients with mild cellulitis, unnecessary blood cultures were obtained (and only one was positive).

Viewpoint

Both of these studies identify clear targets for antibiotic and diagnostic stewardship in regard to SSTI management. Treatment of impetigo with SMX monotherapy could reduce unnecessary antibiotic use and potential adverse effects. Emphasizing the need for beta-lactam monotherapy for nonpurulent cellulitis is an important area for improvement, as are diagnostic stewardship interventions focused on avoidance of unnecessary blood cultures.

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