A prospective observational cohort study in primary care practices to identify factors associated with treatment failure in Staphylococcus aureus skin and soft tissue infections.

BACKGROUND: The incidence of outpatient visits for skin and soft tissue infections (SSTIs) has substantially increased over the last decade. The emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has made the management of S. aureus SSTIs complex and challenging. The objective of this study was to identify risk factors contributing to treatment failures associated with community-associated S. aureus skin and soft tissue infections SSTIs. METHODS: This was a prospective, observational study among 14 primary care clinics within the South Texas Ambulatory Research Network. The primary outcome was treatment failure within 90 days of the initial visit. Univariate associations between the explanatory variables and treatment failure were examined. A generalized linear mixed-effect model was developed to identify independent risk factors associated with treatment failure. RESULTS: Overall, 21% (22/106) patients with S. aureus SSTIs experienced treatment failure. The occurrence of treatment failure was similar among patients with methicillin-resistant S. aureus and those with methicillin-susceptible S. aureus SSTIs (19 vs. 24%; p = 0.70). Independent predictors of treatment failure among cases with S. aureus SSTIs was a duration of infection of ≥7 days prior to initial visit [aOR, 6.02 (95% CI 1.74-19.61)] and a lesion diameter size ≥5 cm [5.25 (1.58-17.20)]. CONCLUSIONS: Predictors for treatment failure included a duration of infection for ≥7 days prior to the initial visit and a wound diameter of ≥5 cm. A heightened awareness of these risk factors could help direct targeted interventions in high-risk populations.

Treatment failure and costs in patients with methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections: a South Texas Ambulatory Research Network (STARNet) study.

OBJECTIVE: To measure the incidence of treatment failure and associated costs in patients with methicillin-resistant Staphylococcus aureus skin and soft tissue infections (SSTIs). METHODS: This was a prospective, observational study in 13 primary care clinics. Primary care providers collected clinical data, wound swabs, and 90-day follow-up information. Patients were considered to have "moderate or complicated" SSTIs if they had a lesion ≥5 cm in diameter or diabetes mellitus. Treatment failure was evaluated within 90 days of the initial visit. Cost estimates were obtained from federal sources. RESULTS: Overall, treatment failure occurred in 21% of patients (21 of 98) at a mean additional cost of $1,933.71 per patient. In a subgroup analysis of patients who received incision and drainage, those with moderate or complicated SSTIs had higher rates of treatment failure than those with mild or uncomplicated SSTIs (36% vs. 10%; P=.04). CONCLUSIONS: One in 5 patients presenting to a primary care clinic for a methicillin-resistant S. aureus SSTI will likely require additional interventions at an associated cost of almost $2,000 per patient. Baseline risk stratification and new treatment approaches are needed to reduce treatment failures and costs in the primary care setting.

Prevalence, severity, and treatment of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) skin and soft tissue infections in 10 medical clinics in Texas: a South Texas Ambulatory Research Network (STARNet) study.

OBJECTIVES: Quantify the prevalence, measure the severity, and describe treatment patterns in patients who present to medical clinics in Texas with community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) skin and soft-tissue infections (SSTI). METHODS: Ten primary care clinics participated in this prospective, community-based study. Clinicians consented patients and collected clinical information, pictures, and wound swabs; data were processed centrally. MRSASelect™ was used for identification. Susceptibilities were determined via Etest®. RESULTS: Overall, 73 of 119 (61%) patients presenting with SSTIs meeting eligibility requirements had CA-MRSA. Among these, 49% were male, 79% were Hispanic, and 30% had diabetes. Half (56%) of the lesions were ≥ 5 cm in diameter. Most patients had abscesses (82%) and many reported pain scores of ≥ 7 of 10 (67%). Many presented with erythema (85%) or drainage (56%). Most received incision and drainage plus an antibiotic (64%). Antibiotic monotherapy was frequently prescribed: trimethoprim-sulfamethoxazole (TMP-SMX) (78%), clindamycin (4%), doxycycline (2%), and mupirocin (2%). The rest received TMP-SMX in combination with other antibiotics. TMP-SMX was frequently administered as one double-strength tablet twice daily. Isolates were 93% susceptible to clindamycin and 100% susceptible to TMP-SMX, doxycycline, vancomycin, and linezolid. CONCLUSIONS: We report a predominance of CA-MRSA SSTIs, favorable antibiotic susceptibilities, and frequent use of TMP-SMX in primary care clinics.