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Comparison of Listeria monocytogenes strains from food and human origin by amplified fragment length polymorphism

Abstract number: O104

Hess D.L., Savelkoul P., De Boer E., Heuvelink A., Spanjaard L., Ang C.W.

Objectives:Listeria monocytogenes is a foodborne pathogen, responsible for neurological, systemic and gastro-intestinal disease with a mortality up to 30%. For the investigation of L. monocytogenes epidemiology highly discriminatory typing methods are needed. The aim of our study was to develop an Amplified Fragment Length Polymorphism (AFLP) for L. monocytogenes, analyze isolates from clinical human and food origin and determine the possibility of differentiation between human and food isolates by AFLP.

Methods: Based on genome sequence analysis we selected restriction enzyme combination HindIII-G and HPyCHIV4-C. With this combination, a collection of 279 L. monocytogenes strains was typed, consisting of 168 human clinical isolates from the Netherlands Reference Laboratory for Bacterial Meningitis (RBM), 111 food isolates from the Food and Consumer Product Safety Authority (VWA), 3 complete genome sequenced strains (ATCC BAA-679 (=EGDe), F2365, HCC23) and L. monocytogenes type strain ATCC 15313. As such, this L. monocytogenes collection is one of the largest collections in the world comparing both clinical and food isolates.

Results: AFLP patterns of the 279 L. monocytogenes isolates were grouped in two major clusters and a few individual isolates. Cluster I included 100 human isolates and 37 isolates of food origin. The human cluster I isolates mainly consisted of the virulent serotype 4b (63/100, 63%) and serotype 1/2b (14/100, 14%). The cluster I isolates originating from food consisted mainly of serotype 1/2b (15/37, 40.5%). These food isolates formed a subcluster within cluster I. Cluster II included 68 human and 74 food isolates, mainly serotype 1/2a (69.1% and 35.1%, respectively).

Conclusion: AFLP allows discrimination of L. monocytogenes in two major clusters. The two clusters show segregation of the virulent 4b serotype into AFLP cluster I, whereas serotype 1/2a predominates in AFLP cluster II. Within cluster I, it is possible to differentiate most food 1/2b isolates from human isolates.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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