Clinical Analysis of Serratia Species Infections in Children and Adolescents Treated for Cancer or Undergoing Hematopoietic Stem Cell Transplantation-A Multicenter Nationwide Study.

Serratia species are Gram-negative pathogens responsible for a wide range of nosocomial infections. This multicenter nationwide retrospective study aimed to describe the epidemiology, clinical characteristics, antimicrobial susceptibility, and outcomes of Serratia infections in pediatric oncology patients and hematopoietic stem cell transplantation (HSCT) recipients in Poland between 2012 and 2023. A total of 36 Serratia infection episodes were identified in patients under 20 years of age, including 30 cases (83.3%) in the oncological (OHD) group and six (16.7%) among HSCT recipients. The median age was 4.30 years. The most common underlying diseases were acute lymphoblastic leukemia (36.1%) and central nervous system tumors (16.7%). Bloodstream infections predominated in OHD patients (33.3%), whereas urinary tract infections were most frequent in HSCT recipients (83.3%). S. marcescens was the most commonly isolated species. More than half of isolates (53.3%) showed antimicrobial resistance, with extended-spectrum β-lactamase (ESBL)-producing strains in 26.7% and AmpC β-lactamase-producing strains in 13.3%. Multidrug resistance occurred in 30%. Treatment most often included amikacin, piperacillin/tazobactam, and carbapenems. Five deaths occurred in the OHD group and one in the HSCT group, none directly related to Serratia infection. Although uncommon, Serratia infections remain clinically relevant due to their high antimicrobial resistance, underscoring the need for antimicrobial stewardship.