Clinical Features and Treatment Outcomes of Bloodstream Infections Caused by Extended-Spectrum β-Lactamase-Producing Escherichia coli Sequence Type 131.

Despite the remarkable emergence of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli sequence type 131 (ST131), the clinical features and outcomes of infections caused by ST131 remain poorly described. From 2011 to 2012, we collected ESBL-producing E. coli isolates from patients with bloodstream infections in 13 hospitals in Korea and compared clinical characteristics and outcomes between ST131 and non-ST131 clones. Of the 110 ESBL-producing isolates, the most common ST was ST131 (30.9%). Multivariate analysis showed that recent operation was the only variable associated with the ST131 clone; other comorbid conditions and clinical features were similar between ST131 and non-ST131 clones. CTX-M-14 and CTX-M-15 were the predominant types of ESBLs, and CTX-M-15 was significantly associated with ST131. The rate of nonsusceptibility to ciprofloxacin was higher in ST131 than in non-ST131 clones (94.1% vs. 75.0%). No significant differences in 30-day mortality rates were found between ST131 and non-ST131 clones. Multivariate analysis revealed that older age (odds ratio [OR]=5.39, 95% confidence interval [CI] 1.22-23.89; p=0.027), nosocomial infection (OR=4.81, 95% CI 1.15-20.15; p=0.032), and higher Pitt bacteremia score (OR=7.26, 95% CI 1.41-37.42; p=0.018) were independent risk factors for 30-day mortality. The ESBL-producing E. coli ST131 clone has emerged and disseminated in Korea. Our findings reveal similarities in clinical and demographic characteristics between ST131 and non-ST131 clones. Although a more resistant profile has been detected in ST131, patients with the ST131 clone did not exhibit a higher mortality rate.