Performance of disk diffusion and broth microdilution for fosfomycin susceptibility testing of multidrug-resistant clinical isolates of Enterobacterales and Pseudomonas aeruginosa

Autores organización

• Maria Fernanda Mojica Medina

  Autor

• 

  Elsa Piedad De La Cadena Vivas

  Autor

• 

  Christian Jose Pallares Gutierrez

  Autor

• 

  Maria Virginia Villegas Botero

  Autor

Autores

• Hernández-Gómez C
• Correa A
• Appel TM

Grupos de investigación

• Grupo de Investigación en Resistencia Antimicrobiana y Epidemiología Hospitalaria RAEH

  

  Investigador

  Maria Virginia Villegas Botero

Resumen

Objectives: This study aimed to evaluate the susceptibility of clinical isolates of Enterobacterales and Pseudomonas aeruginosa to fosfomycin and to determine the concordance of disk diffusion (DD) and broth microdilution (BMD) with agar dilution (AD) for fosfomycin susceptibility testing. Methods: The activity of fosfomycin against 225 clinical isolates of Escherichia coli (n = 64), Klebsiella pneumoniae (n = 68), Enterobacter spp. (n = 28) and P. aeruginosa (n = 65) was tested by AD, DD and BMD. For DD, results were recorded considering and not considering colonies growing within the inhibition halo as recommended by the CLSI and EUCAST, respectively. Escherichia coli breakpoints were used for all Enterobacterales. Results were reported as categorical agreement (CA), major error (ME; false-resistant), very major error (VME; false-susceptible) and minor error (any other discrepancies). Results: Fosfomycin susceptibility of all tested species was >90% by AD. Following CLSI guidelines, DD was the only method reaching =90% CA with AD for E. coli and K. pneumoniae, albeit yielding 6% ME. Neither DD nor BMD achieved acceptable CA percentages for Enterobacter spp. Following EUCAST guidelines, none of the methods had CA = 90%. For Enterobacterales, the best performance of DD is achieved when read as indicated by EUCAST but interpreted according the CLSI breakpoints (>97% CA; 0% VME; =2% ME). For P. aeruginosa, BMD yielded the best results (89% CA; 0% VME; 11% ME). Conclusion: Neither DD or BMD provide accurate results owing to unacceptable ME and VME percentages even when performed as intended by the guidelines. © 2020 The Authors

Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.

Keywords

• Anti-Bacterial Agents; Escherichia coli; Fosfomycin; Microbial Sensitivity Tests; Pseudomonas aeruginosa; carbapenem derivative; cephalosporin derivative; fosfomycin; antiinfective agent; fosfomycin; agar dilution; antibiotic sensitivity; Article; bacterium isolate; broth dilution; disk diffusion; minimum inhibitory concentration; multidrug resistant Enterobacteriaceae; multidrug resistant Escherichia coli; multidrug resistant Klebsiella pneumoniae; multidrug resistant Pseudomonas aeruginosa; nonhuman; priority journal; Escherichia coli; microbial sensitivity test; Pseudomonas aeruginosa