Epidemiological cut-off value and antibiotic susceptibility test methods for azithromycin in a collection of multi-country invasive non-typhoidal Salmonella.
Agar dilution
Antibiotic susceptibility testing
Azithromycin
Broth microdilution
Disk diffusion
Epidemiological cut-off
Gradient test
Non-typhoidal Salmonella
Performance
Journal
Clinical microbiology and infection : the official publication of the European Society of Clinical Microbiology and Infectious Diseases
ISSN: 1469-0691
Titre abrégé: Clin Microbiol Infect
Pays: England
ID NLM: 9516420
Informations de publication
Date de publication:
Dec 2022
Dec 2022
Historique:
received:
25
01
2022
revised:
03
06
2022
accepted:
09
06
2022
pubmed:
24
6
2022
medline:
25
11
2022
entrez:
23
6
2022
Statut:
ppublish
Résumé
Azithromycin is an alternative to treat invasive non-typhoidal Salmonella (iNTS) infections. We determined its epidemiological cut-off (ECOFF) and compared azithromycin susceptibility testing methods for iNTS. We used EUCAST ECOFFinder to determine the minimum inhibitory concentrations (MIC; obtained by broth microdilution) ECOFF and corresponding disk zone diameters of 515 iNTS from blood cultures in Democratic Republic of Congo, Burkina Faso, Rwanda, and Cambodia. Transferable resistance mechanisms were determined by polymerase chain reaction. We compared azithromycin susceptibility testing by semi-automated broth microdilution (customized Sensititre panel; reference), agar dilution, gradient tests (bioMérieux, Liofilchem, HiMedia; read at 80% (MIC80%) and 100% inhibition (MIC100%)), and disk diffusion (Rosco, Oxoid, BD, Liofilchem) for 161 wild- and 198 non-wild-type iNTS. Azithromycin MIC ECOFF was 16 mg/L corresponding to a 12 mm zone diameter; mphA was detected in 192/197 non-wild- and 0/47 wild-type iNTS. Categorical agreement was excellent (≥98%) for all methods. Essential agreement was very good for agar dilution (>90%) but moderate for gradient tests (MIC80%: 52% to 71% and MIC100%: 72% to 91%). Repeatability was good for all methods/brands. Interreader agreement was high for broth microdilution and agar dilution (all ≤1 twofold dilution difference) and disk diffusion (>96% ≤3 mm difference) but lower for gradient tests (MIC80% & MIC100%: 83% to 94% ≤1 twofold dilution difference). Azithromycin ECOFF of iNTS was 16 mg/L, i.e. equal to Salmonella Typhi. Disk diffusion is an accurate, precise, and user-friendly alternative for agar dilution and broth microdilution. Reading gradient tests at 100% instead of 80% inhibition improved accuracy and precision.
Identifiants
pubmed: 35738320
pii: S1198-743X(22)00322-6
doi: 10.1016/j.cmi.2022.06.009
pii:
doi:
Substances chimiques
Azithromycin
83905-01-5
Agar
9002-18-0
Anti-Bacterial Agents
0
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Pagination
1615-1623Informations de copyright
Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.