Campylobacter is among the most common worldwide causes of bacterial gastroenteritis. This organism is part of the commensal microbiota of numerous host species, including livestock, and these animals constitute potential sources of human infection. Molecular typing approaches, especially multilocus sequence typing (MLST), have been used to attribute the source of human campylobacteriosis by quantifying the relative abundance of alleles at seven MLST loci among isolates from animal reservoirs and human infection, implicating chicken as a major infection source. The increasing availability of bacterial genomes provides data on allelic variation at loci across the genome, providing the potential to improve the discriminatory power of data for source attribution. Here we present a source attribution approach based on the identification of novel epidemiological markers among a reference pan-genome list of 1,810 genes identified by gene-by-gene comparison of 884 genomes of Campylobacter jejuni isolates from animal reservoirs, the environment, and clinical cases. Fifteen loci involved in metabolic activities, protein modification, signal transduction, and stress response or coding for hypothetical proteins were selected as host-segregating markers and used to attribute the source of 42 French and 281 United Kingdom clinical C. jejuni isolates. Consistent with previous studies of British campylobacteriosis, analyses performed using STRUCTURE software attributed 56.8% of British clinical cases to chicken, emphasizing the importance of this host reservoir as an infection source in the United Kingdom. However, among French clinical isolates, approximately equal proportions of isolates were attributed to chicken and ruminant reservoirs, suggesting possible differences in the relative importance of animal host reservoirs and indicating a benefit for further nationalscale attribution modeling to account for differences in production, behavior, and food consumption.IMPORTANCE Accurately quantifying the relative contribution of different host reservoirs to human Campylobacter infection is an ongoing challenge. This study, based on the development of a novel source attribution approach, provides the first results of source attribution in Campylobacter jejuni in France. A systematic analysis using gene-by-gene comparison of 884 genomes of C. jejuni isolates, with a pan-genome list of genes, identified 15 novel epidemiological markers for source attribution. The different proportions of French and United Kingdom clinical isolates attributed to

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The continuous emergence of antibiotic resistance demands that novel classes of antibiotics continue to be developed. The division machinery of bacteria is an attractive target because it comprises seven or more essential proteins that are conserved almost throughout the bacteria but are absent from humans. We describe the development of a cell-based assay for inhibitors of cell division and its use to isolate a new inhibitor of FtsZ protein, a key player in the division machinery. Biochemical, cytological, and genetic data are presented that demonstrate that FtsZ is the specific target for the compound. We also describe the effects of more potent analogues of the original hit compound that act on important pathogens, again at the level of cell division. The assay and the compounds have the potential to provide novel antibiotics with no pool of pre-existing resistance. They have provided new insight into cytokinesis in bacteria and offer important reagents for further studies of the cell division machinery.Cell division has been of considerable interest as an antibacterial target because it comprises a group of well conserved proteins that are all essential for the viability of a wide range of bacteria, and their activities are completely different from those of the proteins involved in the division of mammalian cells. A number of compounds that act on components of the cell division machinery have been described (1-7). So far, most of the effort has been directed at the FtsZ protein because it has several biochemical activities that can be assayed in vitro. Here we describe a novel approach to the discovery of inhibitors of bacterial cell division using a cell-based reporter assay. We have used the assay to identify a novel class of antibacterial compounds with potential broadspectrum activity. We show that the compounds act on the highly conserved, essential cell division protein FtsZ in vitro and in vivo. These compounds represent a potential class of new antibiotics that act by a different mechanism than any of the antibiotics currently in clinical use. Molecular Cloning-B. subtilis was transformed by the method described by Anagnostopoulos and Spizizen (8) as modified by Jenkinson (9) or the method described by Kunst and Rapoport (10), except that 20 min after the addition of DNA the transformed cultures were supplemented with 0.66% casamino acids solution. Transformants were selected on Oxoid nutrient agar containing chloramphenicol (5 g/ml). Sporulation was induced by growth in a hydrolyzed casein medium followed by resuspension in a starvation medium. Starvation medium was as described by Karamata and Gross (11). DNA manipulations and E. coli transformations were carried out as described by Sambrook et al. (12). All cloning was done in E. coli DH5␣ (Invitrogen). EXPERIMENTAL PROCEDURESCell Division Dual Reporter Assay-B. subtilis PL16 was grown in hydrolyzed casein medium to exponential phase and centrifuged, and cell pellets were frozen at Ϫ80°C. Frozen cell aliquots of strain PL16 were resuspended in ...

A Multiplex PCR-based assay (m-PCR) with three sets of primers was developed for the detection of all serotypes of Salmonella enterica and the identification of Salmonella Enteritidis and Salmonella Typhimurium. This method was evaluated against a bacteriological method for the analysis of environmental swabs of poultry houses. Samples were preenriched in phosphate-buffered peptone water for 24 h and subjected to three different protocols prior to PCR: (i) an immunomagnetic separation using Dynabeads TM anti-Salmonella (Dynal); (ii) a DNA extraction procedure using the Instagene TM matrix; (iii) an additional step of culture on an MSRV medium. With protocols 1 and 2, eight positive results were found by PCR and 20 with the bacteriological method. Protocol 3 combining MSRV and PCR gave similar results to those obtained from bacteriological methods and allowed Salmonella detection within 2 days.