1310. Antimicrobial Activity of Ceftazidime-Avibactam and Other New β-Lactamase Inhibitor Combinations Tested against Bacterial Isolates from Pediatric Patients from US Medical Centers (2020-2021)

Abstract Background The US FDA expanded the approval of ceftazidime-avibactam (CAZ-AVI) to include pediatric patients aged ≥ 3 months in 2019. We evaluated vitro activities CAZ-AVI, ceftolozane-tazobactam (C-T), meropenem-vaborbactam (MEM-VAB), imipenem-relebactam (IMI-REL), and comparators against Enterobacterales (ENT; n=2,391) P. aeruginosa (PSA; n=414) isolates causing infection from medical centers. Methods Among 21,332 organisms (1/patient) collected 2020-2021 via INFORM Surveillance Program, 2,805 (13.1%) were (≤ 17 years-old [yo]). consecutively 69 centers susceptibility tested by reference broth microdilution methods. Susceptibility results stratified patient age 1 yo [1,040 isolates], 2-5 [580], 6-12 [651], 13-17 [534], type. ENT with an ESBL phenotype screened for β-lactamase genes whole genome sequencing. Results CAZ-AVI MEM-VAB showed complete activity (100.0% susceptible [S]) Enterobacterales, whereas C-T IMI-REL limited some (Table). MEM, ceftriaxone (CRO), gentamicin (GEN) active 99.8%, 87.5%, 93.0% respectively. CRO varied 84.7% (6-12 yo) 89.8% (13-17 yo), GEN 91.9% 94.0% multidrug-resistant (MDR) 3.7% (≤1 4.8% yo). (99.5%S), (99.8%S), (98.4%S) most agents PSA collection, but greater than PSA-resistant subsets. MEM exhibited similar (91.3% inhibited at ≤ 2 mg/L both agents). overall was 91.3%, varying 87.3% 93.2% (2-5 yo).Piperacillin-tazobactam (PIP-TAZ) 87.4%, 85.1% 90.1% Conclusion CAZ-AVI. PSA. differences observed among groups. Disclosures Helio S. Sader, MD, PhD, AbbVie: Grant/Research Support|Cidara: Support|Melinta: Support|Nabriva Therapeutics: Support|Pfizer: Support Cecilia G. Carvalhaes, Dee Shortridge, Support|JMI Laboratory: Employee|Melinta: Support|Menarini: Support|Shionogi: Leonard R. Duncan, Mariana Castanheira, Support|GSK: Support.