2411. Expanded Susceptibility and Resistance Mechanism Testing Among Carbapenem-Resistant Enterobacteriaceae in Connecticut, 2017

Abstract

BackgroundIn Connecticut (CT), submission of clinical carbapenem-resistant Enterobacteriaceae (CRE, resistant to ≥1 carbapenem) isolates to the state public health laboratory (SPHL) was mandated in 2017 for expanded susceptibility and carbapenemase testing. To guide empiric treatment, we created a statewide CRE antibiogram and explored the role of carbapenemase production.MethodsSusceptibility testing was conducted by broth microdilution and disk diffusion and interpreted using Clinical and Laboratory Standards Institute (CLSI) breakpoints, if available. Carbapenemase-producing CRE (CP-CRE) were identified using the modified carbapenem inactivation method (mCIM). Multiplex real-time polymerase chain reaction testing was used to identify genes for common carbapenemases.ResultsOf 198 CRE isolates received by the SPHL in 2017, 166 were confirmed as CRE. After patient deduplication, 147 records remained (46.9% Enterobacter, 35.4% Klebsiella, 14.3% Escherichia coli, and 3.4% other). Most were susceptible to ceftazidime/avibactam (CAZ-AVI) (range: 90–100%) and colistin (range 94–100%). Forty-six (31%) were CP-CRE (39 blaKPC, 4 blaNDM, 2 blaOXA-48-like, and 1 gene unknown). Non-CP-CRE were more frequently susceptible (P <c0.05) than CP-CRE to levofloxacin (67 vs. 26%), moxifloxacin (64 vs. 20%), tigecycline (84 vs. 35%), and tobramycin (84 vs. 35%).ConclusionCP-CRE have demonstrated significant resistance to noncarbapenem antibiotic classes. Most CRE isolates were susceptible to CAZ-AVI and colistin. The predominant carbapenemase gene is blaKPC. This statewide antibiogram can guide empiric prescribing and formulary selection for CRE treatment. Disclosures All authors: No reported disclosures.