Preserving the antimicrobial arsenal: exploring alternatives to carbapenems in ESBL battles within the southeast of Ireland

J Med Microbiol. 2025 Feb;74(2):001955. doi: 10.1099/jmm.0.001955.

Abstract

Introduction. Carbapenems are usually employed as first-line antimicrobials against bacteria harbouring extended-spectrum beta-lactamases (ESBLs). These enzymes confer resistance often to multiple classes of antimicrobials.Hypothesis/Gap Statement. This indiscriminate use of carbapenems and the inevitable development of carbapenem resistance have prompted the need for carbapenem-sparing strategies.Methodology. The non-carbapenem antimicrobial susceptibility patterns of 60 ESBL-producing Enterobacterales (ESBL-PE) isolates responsible for bloodstream infections, in 2022-2023 inclusive, processed at our institution were reviewed.Results. The non-carbapenem antimicrobial susceptibility patterns of 60 ESBL-PE isolates from bloodstream infections during the study period were determined. Escherichia coli was the most common species isolated (87%, n=52), with the majority of cases (73.3%, n=44) originating from a presumed urinary source. Temocillin (TMC), mecillinam (MEC), cefiderocol (FDC), amikacin and fosfomycin (FOS) displayed excellent activity against all ESBL-PE isolates tested, with susceptibility rates of≥85%. Ciprofloxacin and amoxicillin-clavulanic acid were the least efficacious agents, with susceptibility rates≤20%.Conclusions. TMC, MEC, FDC and FOS offer promising alternatives to carbapenems, demonstrating efficacy against ESBL-PE. The use of these agents not only broadens the therapeutic arsenal against ESBL-PE but also mitigates the potential for escalating carbapenem resistance, especially in regions where the incidence of carbapenem resistance is increasing.

Keywords: ESBL; Enterobacterales; antimicrobial resistance; antimicrobial stewardship; antimicrobials; carbapenems; extended-spectrum beta-lactamase; surveillance.

MeSH terms

  • Anti-Bacterial Agents* / pharmacology
  • Anti-Bacterial Agents* / therapeutic use
  • Carbapenems* / pharmacology
  • Carbapenems* / therapeutic use
  • Drug Resistance, Multiple, Bacterial
  • Enterobacteriaceae Infections* / drug therapy
  • Enterobacteriaceae Infections* / epidemiology
  • Enterobacteriaceae Infections* / microbiology
  • Enterobacteriaceae* / drug effects
  • Enterobacteriaceae* / enzymology
  • Enterobacteriaceae* / isolation & purification
  • Humans
  • Ireland / epidemiology
  • Microbial Sensitivity Tests
  • beta-Lactamases* / genetics
  • beta-Lactamases* / metabolism

Substances

  • Anti-Bacterial Agents
  • Carbapenems
  • beta-Lactamases