1432. Population-based Surveillance of Carbapenem-Resistant Enterobacteriaceae (CRE) in Alameda County, 2017-2020

BACKGROUND: Infections caused by carbapenem-resistant Enterobacteriaceae (CRE), especially those that are carbapenemase-producing (CP), are difficult to treat and result in high mortality— the Centers for Disease Control and Prevention (CDC) designates CRE an urgent level threat to public health. Alameda, a northern California county with 1.67 million residents, mandates submission of all carbapenem-resistant isolates Escherichia coli, Klebsiella spp., and Enterobacter spp. We assessed the genetic profiles of CRE isolates and compared to aggregate US data from the same time period. METHODS: Isolates are submitted to the Alameda County Public Health Laboratory (ACPHL), where antimicrobial resistance genetic markers are identified by whole genome sequencing (WGS) using single-end, 150-cycle reactions in a MiSeq (Illumina). Resistance genes were identified using pipelines built in Geneious and confirmed with Resfinder. All epidemiological analyses were conducted using R (Version 4.0). RESULTS: ACPHL performed WGS on 226 CRE isolates submitted between June 2017 and February 2020. A total of 34/95 (36%) Klebsiella spp., 17/60 (28%) E. coli, and 10/71 (14%) Enterobacter spp. a carbapenemase enzyme. Among all Enterobacteriaceae, 21/226 (9%) produced the New Delhi-metallo-β-lactamase (NDM) carbapenemase (Table 1). Among all CRE, 17/226 (8%) were Klebsiella pneumoniae with the multilocus sequence type (MLST) of ST-258. All six Klebsiella pneumoniae ST-35 and ST-11 isolates produced a carbapenemase (Table 2). Table 1: Carbapenemases, Extended Spectrum β-Lactamases (ESBL) and Other β-Lactamases by Organism [Image: see text] Table 2: Organism, Multilocus Sequence Type (MLST) and Carbapenemases Present [Image: see text] CONCLUSION: Compared to US data, Alameda County Klebsiella spp. were nearly half as likely to produce any carbapenemase, and E. coli were three times more likely to produce an NDM carbapenemase. CP-CRE represented a wide array of MLST, with the globally distributed KPC-producing outbreak strain ST-258 being the most frequently identified. Two strains that have been associated with hypervirulent and multidrug resistant infections in Asia, K. pneumoniae ST-35 and ST-11, were also reported. DISCLOSURES: Sam Horwich-Scholefield, MPH CIC, Merck (Research Grant or Support)