Molecular epidemiology of β-lactamases in ceftriaxone-resistant Enterobacterales bloodstream infections in the mid-Atlantic United States

• Published in: Antimicrobial agents and chemotherapy 2025-01, p.e0125824
• Main Authors: Hareza, Dariusz A, Bergman, Yehudit, Jacobs, Emily, Lu, Jennifer, Hanson, Nancy D, Conzemius, Rick, Cosgrove, Sara E, Harris, Anthony D, Simner, Patricia J, Tamma, Pranita D
• Format: Article
• Language: English
• Subjects: Clinical Microbiology; Editor’s Pick; Epidemiology and Surveillance
• ISSN: 0066-4804; 1098-6596; 1098-6596
• DOI: 10.1128/aac.01258-24

Ceftriaxone-resistant Enterobacterales remain a public health threat; contemporary data investigating their molecular epidemiology are limited. Five hundred consecutive ceftriaxone-resistant (MIC ≥ 4 µg/mL) Enterobacterales bloodstream isolates were collected between 2018 and 2022 from three Maryland hospitals. Broth microdilution confirmed antibiotic susceptibilities. Whole-genome sequencing identified extended-spectrum β-lactamase (ESBL) and genes both in bacterial chromosomes (c- ) and on plasmids (p- ). Mutations in promoter or attenuator regions of the c- gene (i.e., gene) with the potential to result in derepression were investigated. The presence of ESBL or genes was confirmed in 497 (99.4%) isolates. Two hundred seventy-nine (55.8%) isolates had both ESBL and genes. ESBL families were identified among 398 (80%) patients: ( = 370), ( = 17), ( = 14), and ( = 5). Ceftriaxone-resistant Enterobacterales species carrying ESBL genes included the following: (67%), (24%), (4%), (2%), complex (2%), (1%), (