Low Frequency of Staphylococcus Aureus in Lower Extremity Skin and Soft Tissue Infections

摘要

BackgroundStaphylococcus aureusis often implicated in skin/soft tissue infections (SSTI). However, SSTI at sites of pressure necrosis and peripheral vascular disease (PVD) are often polymicrobial. The frequency ofS aureusin these infections is uncertain. MethodsWe retrospectively reviewed culture results from adults (January 1, 2015-March 31, 2017), evaluated their records and selected SSTI in lower extremities. The patient demographics, comorbidities, characteristics and culture results were recorded. The results were stratified byS aureusstatus and a composite risk score (RS) was developed (2 points for each difference inS aureusfrequency withP< 0.05 [chi-square test] and 1 point forP?=?0.06-0.1). The predictors ofS aureuswere determined by regression analysis using SSPS software. ResultsWe encountered 356 lower extremity-SSTI (243 foot/ankle, 56 tibia/calf, 30 thigh, 12 hip and 15 groin).S aureuswas detected in 173 (48.6%) cases, 59.6% were methicillin-resistant isolates.S aureuswas more common in lesions without necrosis (56.3% vs. 42.9%;P?=?0.01), with drainage (59.6% vs. 44.7%;P?=?0.02), in male sex (53.2% vs. 40.0%;P?=?0.02) and was less common in patients with PVD (38.1% vs. 50.9%;P?=?0.07), and paraplegia (39.6% vs. 50.0%;P?=?0.2).S aureuswas less common in polymicrobial SSTI (45.0% vs. 58.5%;P?=?0.03). RS of 0-8 correlated with increasingS aureusprevalence from 23.1% (RS?=?0-1) to 78.6% (RS?=?8;P<0.001). The predictors ofS aureuswere drainage (odds ratio [OR]?=?1.83; 95% confidence intervals [CI]: 1.11, 3.02), lack of PVD (OR?=?1.59; CI: 1.03, 2.46) and absence of necrosis (OR?=?1.91; CI: 1.08, 3.40). ConclusionsPatients with suspected polymicrobial lower extremity-SSTI and low RS may not need empirical antistaphylococcal therapy.