Nonfermenting Gram-Negative Bacilli Other Than Pseudomonas and Acinetobacter Species in Pediatric Blood Cultures: A...

Nonfermenting Gram-negative bacilli other than Pseudomonas and Acinetobacter species are increasingly recognized as opportunistic pathogens in pediatric populations, yet their epidemiology and antimicrobial resistance remain poorly defined.

We conducted a multicenter retrospective analysis across 56 hospital centers in 25 European countries, including pediatric blood culture isolates collected between January 2020 and December 2024. Species distribution and antimicrobial susceptibility profiles according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) current guidelines were analyzed.

A total of 382 isolates were included, spanning 19 genera and 40 species. Stenotrophomonas maltophilia was the most frequently identified species (46.9%; n = 179), followed by Roseomonas mucosa (10%; n = 38) and Sphingomonas paucimobilis (7.6%; n = 29). Susceptibility profiles were heterogeneous, with notable resistance across several species. For S. maltophilia, resistance to trimethoprim/sulfamethoxazole exceeded 10% (EUCAST), while full in vitro susceptibility to aztreonam/avibactam was observed. Preserved activity of carbapenems but high resistance to ceftazidime (EUCAST/CLSI), piperacillin/tazobactam (EUCAST/CLSI) and ciprofloxacin (CLSI) was observed for S. paucimobilis. Achromobacter several species showed concerning resistance patterns to carbapenems, piperacillin/tazobactam and trimethoprim/sulfamethoxazole (CLSI).

Nonfermenting Gram-negative bacilli other than Pseudomonas and Acinetobacter species were frequently associated with healthcare exposure and complex resistance profiles. Their management is challenged by a lack of evidence and standardized susceptibility criteria. To optimize management, enhanced surveillance, improved diagnostic standardization and further clinical studies on emerging therapies are needed.