Multidrug-Resistant Gram-Negative Bacillus Bloodstream Infections in Children: Experience From a Tertiary-Care Hospital in Mexico

Abstract

Bacteremia in pediatric populations is an important cause of morbidity and mortality. The emergence of multidrug-resistant (MDR) Gram-negative bacilli, such as Carbapenemase-Producing Enterobacterales (CPE) and carbapenem-resistant Pseudomonas aeruginosa, complicates treatment and negatively impacts clinical outcomes. There are few regional reports documenting the prevalence of multidrug resistance and its relationship to mortality in this age group.Objectives: Estimate the prevalence of bacteremia caused by MDR Gram-negative bacilli in pediatric patients. Describe the relationship between infection source, isolated microorganisms, and mortality. A retrospective observational case series study was conducted. A total of 45 episodes of bacteremia due to MDR Gram-negative bacilli in pediatric patients were included during the study period (2022–2025). Multidrug resistance was defined as resistance to three or more antibiotic classes and/or the presence of carbapenemases. Clinical, microbiological, and outcome variables were collected. The analysis included descriptive statistics, association tests (χ2, Mann–Whitney), and an exploratory logistic model for mortality. The prevalence of MDR was 66.7%, and the proportion of CPE was 37.8%. Overall mortality was 42.1%. The most frequent microorganisms were P. aeruginosa (46.7%), E. coli (22.2%), K. pneumoniae (8.9%), and E. cloacae (6.7%). Multidrug resistance by organism was 100% in Enterobacterales, 57.1% in P. aeruginosa, and 0% in S. maltophilia. The most frequent carbapenemase among Enterobacterales was NDM (53.3%), while VIM was the most common in P. aeruginosa (55%). Mortality was highest in infections caused by E. coli (77.8%) and K. pneumoniae (66.7%). A total of 48.9% of episodes corresponded to central line–associated bloodstream infections (CLABSI), and 37.8% to primary bacteremia, with mortality rates of 47.6% and 35.3%, respectively. Multidrug resistance was significantly associated with mortality (p = 0.043), whereas the presence of CPE, site of blood culture collection, intensive care management, and age showed no statistically significant association. In this pediatric cohort, the prevalence of MDR bacteremia was high and associated with increased mortality, particularly due to Enterobacterales. These findings underscore the need to strengthen surveillance strategies, implement timely diagnostic approaches, and enhance antimicrobial stewardship programs in hospitalized pediatric patients.