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Objective: Resistance to extended-spectrum cephalosporins (ESC) among Enterobacteriaceae (EB) is increasingly prevalent. We sought to determine the clinical outcomes associated with community-onset ESC-resistant (ESC-R) EB urinary tract infections (UTIs) in a US health system., Design: Retrospective cohort study.PatientsAll patients presenting to the emergency departments (EDs) or outpatient practices with EB UTIs between 2010 and 2013 were included. Exposed patients had ESC-R EB UTIs. Unexposed patients had ESC-susceptible EB UTIs and were matched to exposed subjects 1:1 on study year. Multivariable logistic regression analyses were performed to evaluate the association between ESC-R EB UTI and the outcomes of clinical failure and inappropriate initial antibiotic therapy (IIAT)., Results: A total of 302 patients with community-onset EB UTI were included, with 151 exposed and unexposed. On multivariable analyses, UTI due to an ESC-R EB was significantly associated with clinical failure (odds ratio [OR], 7.07; 95% confidence interval [CI], 3.16-15.82; P<.01). Other independent risk factors for clinical failure included infection with Citrobacter spp and need for hemodialysis. UTI due to an ESC-R EB was also significantly associated with IIAT (OR, 4.40; 95% CI, 2.64-7.33; P<.01)., Conclusions: Community-onset UTI due to an ESC-R EB organism is significantly associated with clinical failure, which may be due in part to IIAT. Further studies are needed to determine which patients in the community are at high risk for drug-resistant infection to help inform prompt diagnosis and appropriate antibiotic prescribing for ESC-R EB.

OBJECTIVE To evaluate risk factors for and molecular characteristics of community-onset extended-spectrum cephalosporin-resistant (ESC-R) Enterobacteriaceae (EB) urinary tract infections (UTIs) in a US health system. DESIGN Case-control study. PARTICIPANTS All patients presenting to the emergency department or outpatient practices with EB UTIs from December 21, 2010, through April 22, 2013, were included. Case patients had ESC-R EB UTIs. Control patients had ESC-susceptible EB UTIs and were matched 1:1 on study year. METHODS Risk factors for ESC-R EB UTI were assessed using multivariable conditional logistic regression. A subset of case isolates was evaluated for extended-spectrum beta-lactamases. RESULTS A total of 302 patients with community-onset EB UTI were included, of which 151 were cases. On multivariable analysis, risk factors for ESC-R EB UTI included trimethoprim-sulfamethoxazole use in the prior 6 months (odds ratio, 2.40 [95% CI, 1.22-4.70]; P=.01), older age (1.03 [1.01-1.04]; P<.001), diabetes (2.91 [1.32-6.41]; P=.008), and presentation to the emergency department ( 2.42 [1.31-4.46]; P=.005). The prevalence of extended-spectrum beta-lactamases among 120 case isolates was 52% CTX-M, 29% TEM, 20% OXA, and 13% SHV. The prevalence of AmpC was 25%. Pulsed-field gel electrophoresis of the CTX-M Escherichia coli isolates showed no distinct clusters. CONCLUSIONS Use of trimethoprim-sulfamethoxazole, older age, diabetes, and presentation to the emergency department were associated with community-onset ESC-R EB UTI. There was a high prevalence of CTX-M among our community isolates. Further studies are needed to determine strategies to limit emergence of these organisms in the community. Infect Control Hosp Epidemiol 2016;1433-1439.