In vitro activity of ceftazidime/avibactam against clinical isolates of Enterobacterales and Pseudomonas aeruginosa from Middle Eastern and African countries: ATLAS global surveillance programme 2015-18.

Objectives To assess the in vitro activity of ceftazidime/avibactam against a recent, 2015-18, collection of clinical isolates of Gram-negative bacilli from Middle Eastern and African countries with a focus on isolates from ICUs and with MDR and difficult-to-treat resistance (DTR) phenotypes. Methods Antimicrobial susceptibility testing of 4608 isolates of Enterobacterales (997 isolates from ICU patients) and 1358 isolates of Pseudomonas aeruginosa (374 isolates from ICU patients) was performed by CLSI broth microdilution methodology in a central laboratory. MICs were interpreted using both CLSI (2020) and EUCAST (2020) MIC breakpoints. Results Most isolates of Enterobacterales (Middle East: ICU, 99.1% susceptible, non-ICU, 99.1%; Africa: ICU, 96.9% susceptible, non-ICU, 98.3%) and P. aeruginosa (Middle East: ICU, 93.4%, non-ICU, 92.1%; Africa: ICU, 89.8%; non-ICU, 94.1%) were susceptible to ceftazidime/avibactam. Applying CLSI and EUCAST breakpoints, MDR rates were similar for Enterobacterales (27.8%-36.0% of isolates) and P. aeruginosa (25.0%-36.4%) while DTR rates were lower for Enterobacterales (1.6%-1.8%) than for P. aeruginosa (5.2%-7.4%). Percentage susceptible rates for ceftazidime/avibactam for MDR Enterobacterales were 96.8%-97.5% (Middle East) and 92.5%-94.3% (Africa) while rates for P. aeruginosa were 70.1%-80.0% (Middle East) and 69.5%-78.2% (Africa). 60.5%-65.8% (Middle East) and 38.9%-52.2% (Africa) of isolates of Enterobacterales with DTR phenotypes were ceftazidime/avibactam susceptible as were 29.2%-31.1% (Middle East) and 28.2%-35.8% (Africa) of DTR P. aeruginosa. Conclusions Overall, the isolates of Enterobacterales and P. aeruginosa tested from Middle Eastern and African countries were highly susceptible to ceftazidime/avibactam. Most MDR and many DTR isolates of Enterobacterales and P. aeruginosa were susceptible to ceftazidime/avibactam.