The Burden of Antimicrobial Resistance among Urinary Tract Isolates of Escherichia coli in the United States in 2017

Abstract

30Urinary tract infections (UTIs) caused by Escherichia coli have been historically managed with oral 31 antibiotics including the cephalosporins, fluoroquinolones and trimethoprim-sulfamethoxazole. The use 32 of these agents is being compromised by the increase in extended spectrum β-lactamase (ESBL)-33 producing organisms, mostly caused by the emergence and clonal expansion of E. coli multilocus 34 sequence typing (ST) 131. In addition, ESBL isolates show co-resistance to many of oral agents. 35 Management of UTIs caused by ESBL and fluoroquinolone-resistant organisms is becoming increasingly 36challenging to treat outside of the hospital setting with clinicians having to resort to intravenous agents. 37The aim of this study was to assess the prevalence of ESBL phenotypes and genotypes among UTI 38 isolates of E. coli collected in the US during 2017 as well as the impact of co-resistance to oral agents 39 such as the fluoroquinolones and trimethoprim-sulfamethoxazole. The national prevalence of ESBL 40 phenotypes of E. coli was 15.7% and was geographically distributed across all nine Census regions. 41 Levofloxacin and trimethoprim-sulfamethoxazole-resistance rates were ≥ 24% among all isolates and 42 this co-resistance phenotype was considerably higher among isolates showing an ESBL phenotype (≥ 43 59.2%) and carrying blaCTX-M-15 (≥ 69.5%). The agents with the highest potency against UTI isolates of E. 44 coli, including ESBL isolates showing cross-resistance across oral agents, were the intravenous 45 carbapenems. The results of this study indicate that new oral options with the spectrum and potency 46 similar to the intravenous carbapenems would address a significant unmet need for the treatment of 47 UTIs in an era of emergence and clonal expansion of ESBL isolates resistant to several classes of 48 antimicrobial agents, including oral options. 49 50 51 52 53 54 55 56 57 58 59