Antimicrobial activity of imipenem/relebactam and comparator agents against Gram-negative isolates collected from pediatric patients: SMART 2018-2022 Global Surveillance

Objectives: To evaluate the in vitro susceptibility of recent Gram-negative pathogens collected from pediatric patients to imipenem/relebactam (IMI/REL) and comparator agents.

Methods: From 2018 to 2022, 254 hospitals in 62 countries collected Enterobacterales or P. aeruginosa isolates from patients <18 years old as part of the SMART global surveillance program. MICs were determined using CLSI broth microdilution and interpreted with 2024 CLSI breakpoints. Most isolates non-susceptible to IMI/REL were queried for their acquired β-lactamase content.

Results: Overall, 96.8% of all non-Morganellaceae Enterobacterales (NME) isolates from pediatric patients (n=12,060) were IMI/REL-susceptible. Most NME were also susceptible to imipenem alone (93.9%), meropenem (96.0%), and ertapenem (94.4%); isolates were less susceptible to piperacillin/tazobactam (82.8%), cefepime (76.3%) and ceftazidime (74.4%). NME collected in Asia were the least susceptible to IMI/REL (91.6%), while those from Australia/New Zealand were the most (99.3%). IMI/REL was equally potent against NME isolates regardless of infection source, hospital ward, age, and length of hospitalization. In total 90.8% of all Pseudomonas aeruginosa isolates (n=3,046) were IMI/REL-susceptible; ceftolozane/tazobactam also inhibited >90% of the P. aeruginosa. Regionally, P. aeruginosa isolates from Eastern Europe were least susceptible to IMI/REL. Molecular characterization revealed that, globally, most resistance to IMI/REL among the NME could be attributed to the presence of NDM-type metallo-β-lactamases, while no acquired β-lactamases were detected in approximately half the IMI/REL non-susceptible P. aeruginosa examined.

Conclusion: Based on in vitro data, IMI/REL represents a good therapeutic option for most hospitalized pediatric patients infected with common Gram-negative pathogens.