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http://hdl.handle.net/2445/183494
Title: | Assessment of trimethoprim-sulfamethoxazole susceptibility testing methods for fastidious Haemophilus spp. |
Author: | Sierra Urueña, Yanik Tubau, Fe González Díaz, Aida Carrera-Salinas, Anna Moleres, Javier Bajanca-Lavado, Paula Garmendia, J. Domínguez Luzón, Ma. Ángeles (María Ángeles) Ardanuy Tisaire, María Carmen Marti Marti, Sara |
Keywords: | Malalties bacterianes Antibiòtics Estabilitat dels medicaments Bacils Bacterial diseases Antibiotics Drug stability Bacillus (Bacteria) |
Issue Date: | 1-Jul-2020 |
Publisher: | European Society of Clinical Microbiology and Infectious Diseases |
Abstract: | Objectives: To compare the determinants of trimethoprim-sulfamethoxazole resistance with established susceptibility values for fastidious Haemophilus spp., to provide recommendations for optimal trimethoprim-sulfamethoxazole measurement. Methods: We collected 50 strains each of Haemophilus influenzae and Haemophilus parainfluenzae at Bellvitge University Hospital. Trimethoprim-sulfamethoxazole susceptibility was tested by microdilution, E-test and disc diffusion using both Mueller-Hinton fastidious (MH-F) medium and Haemophilus test medium (HTM) following EUCAST and CLSI criteria, respectively. Mutations in folA, folP and additional determinants of resistance were identified in whole-genome-sequenced isolates. Results: Strains presented generally higher rates of trimethoprim-sulfamethoxazole resistance when grown on HTM than on MH-F, independent of the methodology used (average MIC 2.6-fold higher in H. influenzae and 1.2-fold higher in H. parainfluenzae). The main resistance-related determinants were as follows: I95L and F154S/V in folA; 3- and 15-bp insertions and substitutions in folP; acquisition of sul genes; and FolA overproduction potentially linked to mutations in -35 and -10 promoter motifs. Of note, 2 of 19 H. influenzae strains (10.5%) and 9 of 33 H. parainfluenzae strains (27.3%) with mutations and assigned as resistant by microdilution were inaccurately considered susceptible by disc diffusion. This misinterpretation was resolved by raising the clinical resistance breakpoint of the EUCAST guidelines to ≤30 mm. Conclusions: Given the routine use of disc diffusion, a significant number of strains could potentially be miscategorized as susceptible to trimethoprim-sulfamethoxazole despite having resistance-related mutations. A simple modification to the current clinical resistance breakpoint given by the EUCAST guideline for MH-F ensures correct interpretation and correlation with the reference standard method of microdilution. |
Note: | Versió postprint del document publicat a: https://doi.org/10.1016/j.cmi.2019.11.022 |
It is part of: | Clinical Microbiology and Infection, 2020, vol. 26, num. 7 |
URI: | http://hdl.handle.net/2445/183494 |
Related resource: | https://doi.org/10.1016/j.cmi.2019.11.022 |
ISSN: | 1198-743X |
Appears in Collections: | Articles publicats en revistes (Patologia i Terapèutica Experimental) Articles publicats en revistes (Institut d'lnvestigació Biomèdica de Bellvitge (IDIBELL)) |
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File | Description | Size | Format | |
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709403.pdf | 1.22 MB | Adobe PDF | View/Open |
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