Free access article

DOI: 10.1051/vetres:2001116

Vet. Res. 32 (2001) 119-129

Evaluation of molecular typing methods for Salmonella enterica serovar Typhimurium DT104 isolated in Germany from healthy pigs

Burkhard Malorny, Andreas Schroeter, Cornelia Bunge, Bernhard Hoog, Antje Steinbeck and Reiner Helmuth

Federal Institute for Health Protection of Consumers and Veterinary Medicine, Diedersdorfer Weg 1, 12277 Berlin, Germany

(Received 24 July 2000; accepted 17 November 2000)

Abstract
The discriminatory power of four different DNA based typing methods was tested for the molecular subtyping of Salmonella Typhimurium phage type DT104 isolates. German DT104 strains (n = 133) originating from slaughter pigs were analysed by plasmid profiling, and 32 of them by pulsed-field gel electrophoresis (PFGE) using the restriction enzymes XbaI, SpeI or BlnI, random amplification of polymorphic DNA (RAPD) using 13 different primers and IS200 typing. A resulting subtyping scheme was obtained which is based on the most discriminatory power of the individual methods i.e. plasmid profiling and PFGE with all three enzymes. The index of discrimination obtained by the subtyping scheme was 0.909 closely approaching the maximum value of one. Although minor differences occurred in the molecular DNA pattern of single DT104 strains, a dominating subtyping pattern was observed confirming other studies which showed, that S. Typhimurium DT104 isolates are highly clonal.

Résumé
Évaluation de plusieurs méthodes de typage moléculaire de Salmonella enterica serovar Typhimurium DT104 isolées chez des porcs sains en Allemagne. Le pouvoir discriminant de quatre méthodes différentes basées sur le typage de l'ADN a été testé pour le sous-typage d'isolats de Salmonella Typhimurium DT104. Cent trente trois souches allemandes de DT104 provenant de porcs à l'abattoir ont été analysées par la méthode de profilage de plasmides, et 32 d'entre elles par électrophorèse sur gel en champ pulsé (PFGE) utilisant les enzymes de restriction XbaI, SpeI ou BlnI, par amplification aléatoire d'ADN polymorphe (RAPD) utilisant 13 amorces différentes, et par typage avec IS200. Un protocole de sous-typage, basé sur le plus fort pouvoir discriminant des méthodes individuelles, a été obtenu. Il s'agit du profilage de plasmides associé à l'électrophorèse sur gel en champ pulsé utilisant les trois enzymes de restriction. L'index de discrimination obtenu avec ce protocole de sous-typage était de 0,909, proche de la valeur maximale de 1. Bien que des différences mineures soient apparues dans les profils moléculaires de l'ADN des souches DT104, un profil dominant de sous-type a été observé, confirmant les résultats d'autres études ayant montré que les isolats de Salmonella Typhimurium étaient fortement clonaux.

Key words: RAPD / IS200 / PFGE / plasmid profiling / Salmonella Typhimurium DT104

Mots clés : amplification aléatoire d'ADN polymorphe / IS200 / profilage de plasmide / Salmonella Typhimurium DT104

Correspondence and reprints: Reiner Helmuth Tel.: (49) 30 8412 2233; fax: (49) 30 8412 2953;
    e-mail: r.helmuth@bgvv.de

© INRA, EDP Sciences 2001

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