Abstract and Introduction
Abstract
Background: In the United States, community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as the predominant cause of skin infections. Trimethoprim-sulfamethoxazole (TMP-SMX) and clindamycin are often used as first-line treatment options, but clinical data are lacking.
Methods: We conducted a retrospective cohort study of outpatients with skin and soft tissue infections managed from July 1 to December 31, 2006. Patients younger than 18 years of age were excluded, as were those who had no clinical admission or progress notes; were hospitalized within the 90 days before admission; were hospitalized with polymicrobial, surgical site, catheter-related, or diabetic foot infections; or were discharged to places other than home. Patient demographics, comorbidities, diagnoses, cultures, prescribed antibiotics, susceptibilities, surgical procedures, and health outcomes were extracted from electronic medical records. Patients were divided in 2 cohorts for further analysis: TMP-SMX and clindamycin. The primary study outcome was composite failure defined as an additional positive MRSA culture from any site 5 to 90 days after treatment initiation or an additional intervention during a subsequent outpatient or inpatient visit. Baseline characteristics and failure rates were compared using χ, Fisher's exact, and Wilcoxon rank sum tests.
Results: A total of 149 patients were included in this study. These patients had a median age of 36 years, 55% were men, 71% were Hispanic, 42% were uninsured, and 60% received an incision and drainage procedure. Patients who did not receive incision and drainage were twice as likely to experience the composite failure endpoint (57% vs 29%; P < .001). Failure rates were 25% for patients who received incision and drainage plus antibiotics compared with 60% for patients who received incision and drainage minus antibiotics (P = .03). When patients who did not receive incision and drainage were excluded, there were no significant differences between the TMP-SMX (n = 54) and clindamycin (n = 20) cohorts with respect to composite failures (26% vs 25%), microbiologic failures (13% vs 15%), additional inpatient interventions (6% vs 5%), or additional outpatient interventions (20% vs 20%).
Conclusions: Our findings reinforce the belief that incision and drainage and antibiotics are critical for the management of CA-MRSA skin infections. Patients who receive TMP-SMX or clindamycin for their CA-MRSA skin infections experience similar rates of treatment failure.
Introduction
Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as a common pathogen for skin and soft-tissue infections for which patients increasingly seek treatment in the ambulatory care setting. As of 2005, almost half (47.9%) of all S. aureus infections documented in the outpatient setting nationwide were methicillin resistant, and this percentage is likely to have grown since. Vancomycin has long been the drug of choice for treating CA-MRSA in the hospital setting; however, a major limitation to its use in the outpatient setting is its lack of oral bioavailability. Thus, there is a critical need for establishing effective treatment options for outpatient management of these infections.
Clinicians have begun to use alternative antibiotics, including trimethoprim-sulfamethoxazole (TMP-SMX) and clindamycin, as treatment options in outpatient settings because of their favorable in vitro activity, high oral bioavailability, and excellent tissue penetration. TMP-SMX and clindamycin are recommended by current guidelines as options for the management of skin and soft-tissue infections. Nevertheless, there is limited clinical data to support these recommendations. Moreover, even fewer studies exist to support their use in the outpatient setting. Clinical outcomes data are critically needed to establish TMP-SMX and clindamycin as first-line treatment options for outpatient CA-MRSA skin and soft-tissue infections.
This study reports and compares health outcomes for ambulatory patients who received one of these 2 antibiotics for the treatment of a CA-MRSA skin infection. The primary objective was to compare composite failure rates of oral TMP-SMX and oral clindamycin used for the treatment of CA-MRSA.