706. In Vitro Activity of Ceftazidime–Avibactam and Comparator Agents Against MDR Enterobacteriaceae and Pseudomonas aeruginosa Collected in Latin America During the ATLAS Global Surveillance Program 2016–2017

BACKGROUND: Ceftazidime–avibactam (CAZ-AVI) is a β-lactam/non-β-lactam β-lactamase inhibitor combination that can inhibit class A, C and some class D β-lactamases. Resistance caused by these β-lactamases often results in multidrug-resistance (MDR). This study evaluated the in vitro activity of CAZ-AVI and comparators against MDR Enterobacteriaceae and Pseudomonas aeruginosa isolates collected from patients in Latin America. METHODS: Nonduplicate clinical isolates were collected in 2016–2017 in 6 countries in Latin America. Susceptibility testing was performed using CLSI broth microdilution and interpreted using CLSI 2019 and FDA (tigecycline) breakpoints. MDR was defined as nonsusceptible (NS) (intermediate or resistant) to ≥3 of 7 sentinel drugs: amikacin, aztreonam, cefepime, levofloxacin, colistin, meropenem, and piperacillin–tazobactam. RESULTS: The activity of CAZ-AVI and comparators against all isolates and MDR subsets is shown in the table. MDR rates ranged from 28.4% among E. cloacae to 41.5% among K. pneumoniae. CAZ-AVI was active against >97% of Enterobacteriaceae isolates and maintained activity against >92% of MDR isolates of the examined species. No other tested drug consistently exceeded this activity. Among P. aeruginosa, CAZ-AVI was active against 87% of all isolates and 63% of MDR isolates; only colistin was more active. The two most common MDR phenotypes among Enterobacteriaceae were (1) NS to aztreonam, cefepime, and levofloxacin (n = 580, 41% of all MDR Enterobacteriaceae; 100% susceptible to CAZ-AVI) and (2) NS to aztreonam, cefepime, levofloxacin, and piperacillin–tazobactam (n = 301, 21% of all MDR isolates; 99.7% susceptible to CAZ-AVI). The two most common MDR phenotypes among P. aeruginosa were (1) NS to all sentinel drugs except colistin (n = 154, 33% of all MDR isolates; 30.5% susceptible to CAZ-AVI) and (2) NS to all drugs except colistin and amikacin (n = 97, 21% of all MDR isolates; 70.1% susceptible to CAZ-AVI). CONCLUSION: These in vitro data suggest that CAZ-AVI can be an effective treatment option for infections caused by MDR Enterobacteriaceae and P. aeruginosa collected in Latin America. [Image: see text] DISCLOSURES: All authors: No reported disclosures.