1358. In vitro Activity of Ceftazidime–Avibactam and Comparator Agents Against Pseudomonas aeruginosa Causing Intra-Abdominal, Lower Respiratory, and Urinary Tract Infections Collected in Latin America as Part of the INFORM Global Surveillance Program, 2012–2016

Background The non-β-lactam β-lactamase inhibitor avibactam (AVI) is active against class A, C, and some class D β-lactamases, in combination with ceftazidime (CAZ) has been approved by the FDA and EMA for treatment of intra-abdominal infections (IAI), lower respiratory tract infections (LRTI), and urinary tract infections (UTI). This study reports on the in vitro activity of (CAZ-AVI) and comparators vs. P. aeruginosa collected from IAIs, LRTIs, and UTIs in Latin America as part of the INFORM surveillance study from 2012 to 2016. Methods For INFORM surveillance over 2012–2016 in Latin America, 1,595 nonduplicate P. aeruginosa isolates linked to IAIs, LRTIs, and UTIs were collected from 26 clinical sites in six countries. Susceptibility testing was done using broth microdilution according to CLSI guidelines and using CLSI 2018 breakpoints. CAZ was tested with AVI at a fixed concentration of 4 mg/mL. Meropenem (MEM) nonsusceptible organisms were screened for β-lactamase genes by PCR. Results Among the full collection of P. aeruginosa, CAZ-AVI showed consistently higher % susceptibilities than all comparators except for colistin (CST) for all infection sources. The addition of AVI to CAZ resulted in an increase in susceptibility ranging from 14.2% (IAI) to 19.5% (UTI). Against the non-metallo-β-lactamase (MBL) harboring subset, CAZ-AVI showed extremely potent activity (MIC90, 8 mg/mL) for all infection sources. In this subset, the activity of CAZ-AVI approached that of colistin for IAIs (susceptibility of 93.3% vs. 96.4%, respectively). Conclusion CAZ-AVI demonstrated very good in vitro activity against P. aeruginosa isolates, especially those without MBLs. More isolates were susceptible to CAZ-AVI than to MEM for all infection types. Disclosures M. Wise, Pfizer Inc.: Consultant, Consulting fee. IHMA, Inc.: Employee, Salary. K. Kazmierczak, Pfizer Inc.: Consultant, Consulting fee. IHMA, Inc.: Employee, Salary. G. G. Stone, Pfizer Inc.: Employee, Salary. AstraZeneca: Former Employee and Shareholder, Salary. D. Sahm, Pfizer Inc.: Consultant, Consulting fee. IHMA, Inc.: Employee, Salary.