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

BACKGROUND: In 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. METHODS: Susceptibility 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. RESULTS: Of 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 bla(KPC), 4 bla(NDM), 2 bla(OXA-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%). CONCLUSION: CP-CRE have demonstrated significant resistance to noncarbapenem antibiotic classes. Most CRE isolates were susceptible to CAZ-AVI and colistin. The predominant carbapenemase gene is bla(KPC). This statewide antibiogram can guide empiric prescribing and formulary selection for CRE treatment. [Image: see text] DISCLOSURES: All authors: No reported disclosures.