Variable tellurite resistance profiles of clinically-relevant Shiga toxin-producing Escherichia coli (STEC) influence their recovery from foodstuffs
2016
Kerangart, Stephane | Douellou, Thomas | Delannoy, Sabine | Fach, Patrick | Beutin, Lothar | Thevenot-Sergentet, Delphine | Cournoyer, Benoit | Loukiadis, Estelle | Laboratoire d'Ecologie Microbienne - UMR 5557 (LEM) ; Institut National de la Recherche Agronomique (INRA)-Université Claude Bernard Lyon 1 (UCBL) ; Université de Lyon-Université de Lyon-Ecole Nationale Vétérinaire de Lyon (ENVL)-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS)-Centre National de la Recherche Scientifique (CNRS) | Centre National de la Recherche Scientifique (CNRS) | Université Claude Bernard Lyon 1 (UCBL) ; Université de Lyon | Unité Mixte de Recherche Fromagère (UMRF) ; Institut National de la Recherche Agronomique (INRA) | Laboratoire de sécurité des aliments de Maisons-Alfort (LSAl) ; Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail (ANSES) | National Reference Laboratory for Escherichia coli (Including VTEC) - Department of Biological Safety ; Bundesinstitut für Risikobewertung - Federal Institute for Risk Assessment (BfR) | Laboratoire national de référence des E. coli /LMAP Laboratory, National Reference Laboratory for Escherichia coli (LMAP) ; Université de Lyon-VetAgro Sup - Institut national d'enseignement supérieur et de recherche en alimentation, santé animale, sciences agronomiques et de l'environnement (VAS) | Université de Lyon | bioMerieux; French Ministry of Agriculture; CNRS; University Lyon 1; VetAgro Sup
Tellurite (Tel)-amended selective media and resistance (Tel-R) are widely used for detecting Shiga toxin-producing Escherichia coli (STEC) from foodstuffs. Tel-R of 81 O157 and non-O157 STEC strains isolated from animal, food and human was thus investigated. Variations of STEC tellurite minimal inhibitory concentration (MIC) values have been observed and suggest a multifactorial and variable tellurite resistome between strains. Some clinically-relevant STEC were found highly susceptible and could not be recovered using a tellurite-based detection scheme. The ter operon was highly prevalent among highly Tel-R STEC but was not always detected among intermediately-resistant strains. Many STEC serogroup strains were found to harbor sublines showing a gradient of MIC values. These Tel-R sublines showed statistically significant log negative correlations with increasing tellurite concentration. Whatever the tellurite concentration, the highest number of resistant sublines was observed for STEC belonging to the O26 serogroup. Variations in the number of these Tel-R sublines could explain the poor recovery of some STEC serogroups on tellurite-amended media especially from food products with low levels of contamination. Comparison of tellurite MIC values and distribution of virulence-related genes showed Tel-R and virulence to be related. (C) 2016 Elsevier Ltd. All rights reserved.
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