1068. Antimicrobial Activity of Aztreonam-Avibactam and Comparator Agents against Gram-Negative Bacteria Isolated from Bloodstream and Complicated Urinary Tract Infections in Europe, Asia, and Latin America (2019-2020)

Abstract

Background. Aztreonam (ATM) is a monobactam stable to hydrolysis by metallo-β-lactamases (MBLs). Avibactam (AVI) is a non-β-lactam β-lactamase inhibitor that inhibits serine β-lactamases (BLs) such as ESBLs, KPCs, AmpC, and some OXAs. ATM-AVI is under clinical development for the treatment of serious infections caused by gram-negative bacteria (GNB), including MBL-producers. We evaluated ATM-AVI activity against GNB causing bloodstream (BSI) and complicated urinary tract infections (cUTI). Methods. 10,103 GNB isolates (5,314 from BSI and 4,789 from cUTI) were consecutively collected (1/patient) from 66 medical centers located in Western Europe (W-EU; n=5,238; 25 centers in 10 countries), Eastern Europe (E-EU; n=1,729; 13 centers in 10 countries), the Asia-Pacific region (APAC; n=1,817; 17 centers in 9 countries), and Latin America (LATAM; n=1,319; 11 centers in 7 countries) in 2019 (n=5,030) and 2020 (n=5,073). Susceptibility (S) testing was performed by reference broth microdilution methods in a central laboratory. Results. Overall, 99.9% of Enterobacterales (ENT; MIC50/90, ≤0.03/0.12 mg/L), including 99.7% of carbapenem-resistant ENT (CRE; MIC50/90, 0.25/0.5 mg/L), were inhibited at an ATM-AVI MIC of ≤8 mg/L (Table). CRE rates among BSI/cUTI isolates were 2.3%/0.6% in W-EU, 9.5%/6.1% in E-EU, 3.3%/2.8% in APAC, and 8.1%/5.2% in LATAM (4.2%/2.7% overall). ATM-AVI was very active against MDR (MIC50/90, 0.06/0.5 mg/L; 99.6% inhibited at ≤8 mg/L) and XDR (MIC50/90, 0.25/0.5 mg/L; highest MIC, 2 mg/L) ENT. Among P. aeruginosa, the percentage of isolates inhibited at ≤8 mg/L of ATM-AVI (78.3%) was similar to the S rates for piperacillin-tazobactam (78.8%), meropenem (79.1%), and ceftazidime (80.6%). Among S. maltophilia isolates, 100. 0% were inhibited at ≤8mg/L of ATM-AVI and 95.4% were S to cotrimoxazole. ATM-AVI was highly active against Aeromonas spp. (highest MIC, 0.25 mg/L) and showed good activity against B. cepacia (MIC50/90, 4/16 mg/L). Conclusion. ATM-AVI exhibited potent and consistent activity against ENT (including CRE, MDR, and XDR isolates) from W-EU, E-EU, APAC, and LATAM. Our results support clinical development of ATM-AVI to treat BSI and cUTI caused by ENT, P. aeruginosa, S. maltophilia, B. cepacia and Aeromonas spp.