659. In Vitro Activity of Ceftazidime-Avibactam and Comparator Agents against Enterobacterales Collected from Patients with Bloodstream Infections (BSI) as Part of the ATLAS (India) Surveillance Program, 2019-2020

Abstract Background Ceftazidime-avibactam (CAZ-AVI) is indicated for patients with bacteremia that occurs in association complicated intra-abdominal infection (cIAI), complicated urinary tract infection (cUTI) and hospital-acquired pneumonia (HAP). The present report evaluated the in vitro activity of CAZ-AVI and comparators against Enterobacterales clinical isolates collected from BSI as part of the ATLAS (The Antimicrobial Testing Leadership and Surveillance) surveillance program in 2019-2020 from India. Methods A total of 2126 Enterobacterales (493 from blood samples) non-duplicate clinically significant isolates, were collected from 2019-2020. In vitro activity of Ceftazidime-avibactam and its comparators were assessed against Enterobacterales blood isolates. Results Overall susceptibility to the β -lactam/β -lactamase inhibitor (BL-BLI) was 60 -76% for Enterobacterales. with highest susceptibility to Ceftazidime-avibactam. Overall highest susceptibility (97%) was noted for Tigecycline for Enterobacterales(n=476).The susceptibility to colistin was lower(83%) in Enterobacterales (n=409). Among 168 CR-Enterobacterales (CRE), Ceftazidime avibactam showed 29% susceptibility (n=49) while susceptibility to Tigecycline was 96%(n=161) followed by Colistin at 84%(n=141). Molecular analysis for CRE isolates showed 55 % (n=93) to be OXA-48 like producers (with or without NDM) ,68%(n=114)to be NDM producers (with or without OXA- 48) and 30%(n=51) to be co producers of OXA-48 like & NDM. In vitro activity of commonly used antibiotics against Enterobacterales, blood isolates (2019-2020) Conclusion Caz-Avi showed overall good susceptibility against the blood isolates tested hence it may be a valuable therapeutic option for treating BSI caused by MBL-negative Enterobacterales. Tigecycline followed by Colistin showed the highest susceptibilities. Tigecycline attains very low plasma concentrations and is not licensed for use in blood stream infections, while the use of colistin may be limited by the lack of CLSI susceptibility breakpoints and safety concerns. Disclosures Abhisek Routray, PhD, Pfizer India Limited: Advisor/Consultant Akshata Mane, MD, Pfizer India Limited: Advisor/Consultant|Pfizer India Limited: Stocks/Bonds.