Campylobacter has emerged as the major cause of food- and waterborne bacterial gastro-enteritis all over the world. The annual public health burden in the European Union is estimated at 900,000 cases of campylobacteriosis, causing global health costs of over €2.4 billion. While the majority of cases can be attributed to poultry sources, still 40-50 per cent of the illnesses remain of unknown origin. Numerous, mostly molecular fingerprinting methods have been developed for elucidating this epidemiological gap of knowledge. The genetic diversity of Campylobacter is huge, especially in environmental water systems, but the original animal reservoirs are hardly ever identified. It appears that host species association is more important than geography, as e.g. wild bird-species-specific genotypes were described all over the globe.In recent years, a new transversal technique has been implemented for the routine characterization of bacteria, i.e. Matrix-Assisted Laser Desorption/Ionisation coupled to Time of Flight Mass Spectrometry (Maldi-Tof MS). This toolbox for whole-cell proteomic and macromolecular profiling enables robust, very rapid, accurate and cheap classification of microorganisms, including Campylobacter species identification.In the present project, the goal is to go a step further into subspecies typing of the major causative agent of human campylobacteriosis, C. jejuni, using the Maldi-Tof MS approach. Therefore, a collection of 200 of both environmental and clinically-relevant C. jejuni isolates from 4 different continents in the world will be constituted. The Maldi-Tof MS fingerprints will be related to genetic fingerprints obtained by Multi-Locus Sequence Typing (MLST). Ideally, robust, constant host signatures and biomarkers of origin, pathogenicity or antibiotic resistance will be identified among the collection, and a database will be created.Concretely, Dr Christian Penny who is an environmental and public-health microbiologist at the Centre de Recherche Public – Gabriel Lippmann and specialized in microbial detection and fingerprinting would gather the collection of strains in collaboration with partners from Luxembourg, the USA and New Zealand. After complete molecular typing of the C. jejuni strains by an extended MLST scheme, the collection will be profiled by Maldi-Tof MS during a mobility stay of Dr Penny in the research group of Dr Todd Sandrin at the Arizona State University in Phoenix, USA. Dr Sandrin is a key player and internationally recognized expert in enhanced subspecies barcoding and clustering of pathogenic bacteria of animal and environmental origin.