1679. Susceptibility of Gram-Negative Clinical Isolates Collected from the USA in 2020 to Eravacycline and Comparators

Abstract Background Eravacycline is a fully-synthetic, fluorocycline antibacterial approved by the FDA and EMA for the treatment of complicated intra-abdominal infections (cIAI) in patients ≥18 years of age. The activity of eravacycline has been surveyed annually since 2013. Here we present data on the in vitro activity of eravacycline and comparators against Gram-negative pathogens isolated in the USA during 2020. Methods Isolates were collected from patients from various body sites. Minimum inhibitory concentrations (MICs) were determined by CLSI broth microdilution. Antibiotic susceptibility was determined using current CLSI breakpoints, except for eravacycline and tigecycline where FDA and EUCAST breakpoints were used due to a lack of CLSI breakpoints. Multi-drug resistant (MDR) was defined as resistance to ≥3 antibiotics including aztreonam, a carbapenem (meropenem or ertapenem), third or fourth generation cephalosporin (cefepime,cefotaxime,ceftazidime, or ceftriaxone), gentamicin, levofloxacin, piperacillin/tazobactam, tetracycline or tigecycline. Results Summary MIC and susceptibility data for eravacycline and select comparators are shown in the Table. Eravacycline MIC90 against Enterobacterales combined was 0.5 μg/mL (MDR Enterobacterales and individual species ranged from 0.25 to 1 μg/mL) and susceptibility was 93.9% using both FDA and EUCAST breakpoints. Tigecycline MIC90 against Enterobacterales was 1 μg/mL and susceptibility using FDA breakpoints (set in 2005) was 96.8%, whereas susceptibility by EUCAST breakpoints (set in 2019) was 87.8%. Eravacycline MIC50 and MIC90 against A. baumannii was 0.5 and 2 μg/mL, respectively; being at least 4-fold lower than that observed for tigecycline. Conclusion Eravacycline in vitro activity has remained unchanged since 2013, with comparable annual susceptibility rates observed against clinically important Gram-negative pathogens. These data also highlight that FDA breakpoints for tigecycline against Enterobacterales need urgent review to avoid potential false reporting of tigecycline susceptibility. In contrast, eravacycline FDA breakpoints are in keeping with those published by EUCAST and can be used to predict the clinical outcome of eravacycline treatment. Disclosures Tony Hodges, MD, LaJolla Pharmaceutical: Chief Medical Officer|LaJolla Pharmaceutical: Stocks/Bonds.