Epidemiologic Patterns and Clinical Implications of Genotypic Resistance Mechanism for Carbapenem-Resistant Enterobacteriaceae (CRE)Surveillance Isolates from Los Angeles County

BACKGROUND: Carbapenem-resistant Enterobacteriaceae (CRE), particularly carbapenemase-producing (CP) CRE, are an urgent public health threat. CRE with blaKPC have been most commonly reported, but blaNDM and other genotypes have epidemiologic and clinical significance. We seek to define epidemiologic patterns and antimicrobial susceptibility implications of genotypic resistance (R) mechanism in LAC. METHODS: LAC Department of Public Health (DPH) Public Health Laboratory (PHL) conducted CRE laboratory surveillance of 31 clinical microbiology labs representing 34% (34/96) hospitals and 1 large regional lab serving 60% of SNFs from January 2015 to December 2016. Data on antimicrobial susceptibility testing (AST) was conducted by local laboratories and methodology varies by each submitting clinical lab. Isolates were sent to DPH PHL for identification of carbapenem resistance mechanism using Nanosphere Verigene BC-GN to detect carbapenemase genes; blaOXA, blaVIM, blaNDM, blaKPC, and blaIMP. RESULTS: During the study period, 843 CRE isolates were submitted to DPH for further analysis. CRE isolates were submitted from 34 hospitals (n = 604, mean 2 isolates/facility/month, range 1–7 isolates); 239 isolates submitted from regional SNF lab (range 2-54 isolates/month). Resistance mechanisms were identified in 684 Klebsiella spp., 61 E. coli, 45 Enterobacter spp., 10 Acinetobacter Baumannii, and other organisms. blaKPC was identified in 653 (77.5%) isolates, blaOXA in 17 (2%) isolates, and blaVIM in 2 isolates; 75 (9%) isolates did not have a marker detected. AST data and carbapenemase gene detection data were complete for 252 (30%) isolates, 250 isolates from hospitals and 2 SNF isolates; 29 isolates from hospitals were identified as pan-resistant, AST results for blaKPC differed from non-blaKPC isolates for tobramycin, amikacin, ciprofloxacin, aztreonam, ceftolazone tazobactam, ceftazidime avibactam (P < 0.05 for all). CONCLUSION: CRE surveillance in a large urban setting continues to demonstrate that CRE Burden varies across individual facilities. Molecular epidemiology indicate that KPC remains the predominant carbapenemase, but NDM and other non-KPC mechanisms are recognized. Preliminary AST testing suggests that resistance mechanism has implications for antibiotic therapy. DISCLOSURES: All authors: No reported disclosures.