The Prevalence of Multidrug Resistance in Enterobacterales Is Higher in Patients Undergoing Hematopoietic Stem Cell Transplantation

Background: Antimicrobial resistance is a global public health emergency. Patients undergoing hematopoietic stem cell transplantation (HCT) are at increased risk for severe infections with multidrug-resistant (MDR) organisms, although more data are needed on the relative burden of MDR Enterobacterales (MDR-E) in immunocompromised populations. In this study, we compare the prevalence of Enterobacterales resistance in cultures from patients undergoing HCT with that of non-HCT patients seeking care at a large healthcare system in North Carolina, USA. Methods: We analyzed electronic health data from 52 067 patients aged ≥18 years with a culture positive for Enterobacterales species (2000-2023). Of these, 271 had undergone HCT prior to culture-recovered Enterobacterales. We compared resistance trends over time for specific antibacterial classes using a 5-year moving average and used generalized linear models to estimate prevalence ratios and differences of MDR-E in HCT versus non-HCT patients. Results: HCT recipients overall had a higher prevalence of MDR-E (37.7% vs 19.4%) and resistance for all individual antibiotic classes analyzed. Comparing HCT vs non-HCT groups, the highest prevalence ratio was observed for resistance to aminoglycosides (2.10 [95% confidence interval {CI}, 1.65-2.68]); the largest adjusted absolute difference in nonsusceptibility was observed with quinolones (20.4 [95% CI, 14.9-25.8]). MDR-E infections were associated with double all-cause mortality at 1 year. Conclusions: This large longitudinal study highlights how antimicrobial resistance has consistently been a substantial problem in HCT recipients over the prior 2 decades. Targeting antimicrobial resistance mitigation efforts will be key in reducing the risk of MDR infections in HCT.