Rapid and reliable identification of Arcobacter and Helicobacter species, and their distinction from phenotypically similar Campylobacter species, has become increasingly important, since many of them are now recognized as human and/or animal pathogens. Matrix-associated laser desorption/ ionization-time of flight (MALDI-TOF) MS has been shown to be a rapid and sensitive method for characterization of micro-organisms. In this study, we therefore established a reference database of selected Arcobacter, Helicobacter and Campylobacter species for MALDI-TOF MS identification. Besides the species with significance as food-borne pathogens -Arcobacter butzleri, Helicobacter pullorum, Campylobacter jejuni and Campylobacter coli -several other members of these genera were included in the reference library to determine the species specificity of the designed MALDI Biotyper reference database library. Strains that made up the reference database library were grown on Columbia agar, and yielded reproducible and unique mass spectra profiles, which were compared with the Bruker Biotyper database, version 2. The database was used to identify 144 clinical isolates using whole spectral profiles. Furthermore, reproducibility of MALDI-TOF MS results was evaluated with respect to age and/or storage of bacteria and different growth media. It was found that correct identification could be obtained even if the bacteria were stored at room temperature or at 4 6C up to 9 days before being tested. In addition, bacteria were correctly identified when grown on Campylosel agar; however, they were not when grown on modified charcoal cefoperazone deoxycholate agar. These results indicate that MALDI-TOF MS fingerprinting is a fast and reliable method for the identification of Arcobacter and Helicobacter species, and their distinction from phenotypically similar Campylobacter species, with applications in clinical diagnostics. INTRODUCTIONIdentification of species belonging to the Arcobacter, Helicobacter and Campylobacter genera has become increasingly important, since many of them are recognized as human and/or animal pathogens. Arcobacter butzleri was found to be the fourth most frequently isolated Campylobacter-like organism in human clinical samples, before Campylobacter lari, but after Campylobacter jejuni, Campylobacter coli and Campylobacter fetus, in Belgium and in France (Prouzet-Mauleon et al., 2006;Vandenberg et al., 2004). On several occasions, Helicobacter pullorum has been isolated from poultry (Zanoni et al., 2007; Ceelen et al., 2007;Atabay et al., 1998;Neubauer & Hess, 2006b). A number of research groups have associated H. pullorum with gastroenteritis, diarrhoea, and liver and gall bladder disease in human patients (Young et al., 2000;Stanley et al., 1994;Castera et al., 2006;Rocha et al., 2005). For H. pullorum there is a lack of phenotypic identification methods, and as a result, this bacterium is commonly misidentified as thermophilic Campylobacter (Atabay et al., Reference strains used in this study to generate the datab...

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The objectives of this study were to evaluate the presence of thermophilic Campylobacter in feces of calves with and without diarrhea on dairy farms and to survey farm characteristics and management practices to define risk factors for the presence of Campylobacter. Fifty dairy farms were chosen based on the presence of calf diarrhea, and 50 farms in which calves were free from diarrhea served as a standard of comparison. In total, fecal samples were taken from 382 calves. Farm data and management practices were surveyed using a questionnaire on farm. Campylobacter were isolated from fecal samples and colonies were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis. Campylobacter spp., mainly Campylobacter jejuni (93% of isolated species), were detected on 33% of the farms and in 14.9% of the calves. Detection of Campylobacter did not differ between farms or between calves with and without diarrhea, although we found a tendency for calves suffering from diarrhea to shed Campylobacter more often. Calves may act as a reservoir of Campylobacter and may therefore lead to infections of other animals and humans. To define control strategies to reduce Campylobacter in calves, we identified on-farm risk factors. The presence of poultry on the farm, the time of cow-calf separation following birth, the use of an individual bucket for each calf, the feeding of waste milk, and the duration of individual housing were variables significantly associated with the appearance or absence of Campylobacter.