Open Access Highly Accessed Research article

Closely related Campylobacter jejuni strains from different sources reveal a generalist rather than a specialist lifestyle

Eugenia Gripp1, Daniela Hlahla1, Xavier Didelot2, Friederike Kops1, Sven Maurischat3, Karsten Tedin3, Thomas Alter47, Lüppo Ellerbroek4, Kerstin Schreiber5, Dietmar Schomburg5, Traute Janssen3, Patrick Bartholomäus1, Dirk Hofreuter1, Sabrina Woltemate1, Markus Uhr1, Birgit Brenneke1, Petra Grüning6, Gerald Gerlach6, Lothar Wieler2, Sebastian Suerbaum1* and Christine Josenhans1*

Author Affiliations

1 Institute for Medical Microbiology, Hannover Medical School, Hannover, Germany

2 Department of Statistics, University of Oxford, UK

3 Institute for Microbiology and Epizootics, Freie Universität Berlin, Germany

4 Federal Institute for Risk Assessment, Berlin, Germany

5 Institute for Biochemistry and Biotechnology, Technische Universität Braunschweig, Germany

6 Institute for Microbiology, University of Veterinary Medicine, Hannover, Germany

7 Institute of Food Hygiene, Freie Universität Berlin, Germany

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BMC Genomics 2011, 12:584  doi:10.1186/1471-2164-12-584

Published: 28 November 2011

Abstract

Background

Campylobacter jejuni and Campylobacter coli are human intestinal pathogens of global importance. Zoonotic transmission from livestock animals or animal-derived food is the likely cause for most of these infections. However, little is known about their general and host-specific mechanisms of colonization, or virulence and pathogenicity factors. In certain hosts, Campylobacter species colonize persistently and do not cause disease, while they cause acute intestinal disease in humans.

Results

Here, we investigate putative host-specificity using phenotypic characterization and genome-wide analysis of genetically closely related C. jejuni strains from different sources. A collection of 473 fresh Campylobacter isolates from Germany was assembled between 2006 and 2010 and characterized using MLST. A subset of closely related C. jejuni strains of the highly prevalent sequence type ST-21 was selected from different hosts and isolation sources. PCR typing of strain-variable genes provided evidence that some genes differed between these strains. Furthermore, phenotypic variation of these strains was tested using the following criteria: metabolic variation, protein expression patterns, and eukaryotic cell interaction. The results demonstrated remarkable phenotypic diversity within the ST-21 group, which however did not correlate with isolation source. Whole genome sequencing was performed for five ST-21 strains from chicken, human, bovine, and food sources, in order to gain insight into ST-21 genome diversity. The comparisons showed extensive genomic diversity, primarily due to recombination and gain of phage-related genes. By contrast, no genomic features associated with isolation source or host were identified.

Conclusions

The genome information and phenotypic data obtained in vitro and in a chicken infection model provided little evidence of fixed adaptation to a specific host. Instead, the dominant C. jejuni ST-21 appeared to be characterized by phenotypic flexibility and high genetic microdiversity, revealing properties of a generalist. High genetic flexibility might allow generalist variants of C. jejuni to reversibly express diverse fitness factors in changing environments.