%0 Journal Article %A Andreas Leimbach %A Anja Poehlein %A John Vollmers %A Rolf Daniel %A Ulrich Dobrindt %T No evidence for a bovine mastitis Escherichia coli pathotype %D 2016 %R 10.1101/096479 %J bioRxiv %P 096479 %X Background Escherichia coli bovine mastitis is a disease of significant economic importance in the dairy industry. Molecular characterization of mastitis-associated E. coli (MAEC) did not result in the identification of common traits. Nevertheless, a mammary pathogenic E. coli (MPEC) pathotype has been proposed suggesting virulence traits that differentiate MAEC from commensal E. coli. The present study was designed to investigate the MPEC pathotype hypothesis by comparing the genomes of MAEC and commensal bovine E. coli.Results We sequenced the genomes of eight E. coli isolated from bovine mastitis cases and six fecal commensal isolates from udder-healthy cows. We analyzed the phylogenetic history of bovine E. coli genomes by supplementing this strain panel with eleven bovine-associated E. coli from public databases. The majority of the isolates originate from phylogroups A and B1, but neither MAEC nor commensal strains could be unambiguously distinguished by phylogenetic lineage. The gene content of both MAEC and commensal strains is highly diverse and dominated by their phylogenetic background. Although individual strains carry some typical E. coli virulence-associated genes, no traits important for pathogenicity could be specifically attributed to MAEC. Instead, both commensal strains and MAEC have very few gene families enriched in either pathotype. Only the aerobactin siderophore gene cluster was enriched in commensal E. coli within our strain panel.Conclusions This is the first characterization of a phylogenetically diverse strain panel including several MAEC and commensal isolates. With our comparative genomics approach we could not confirm previous studies that argue for a positive selection of specific traits enabling MAEC to elicit bovine mastitis. Instead, MAEC are facultative and opportunistic pathogens recruited from the highly diverse bovine gastrointestinal microbiota. Virulence-associated genes implicated in mastitis are a by-product of commensalism with the primary function to enhance fitness in the bovine gastrointestinal tract. Therefore, we put the definition of the MPEC pathotype into question and suggest to designate corresponding isolates as MAEC.AMR-SSuTantimicrobial multidrug resistance to streptomycin, sulfonamide, and tetracyclineAPECavian pathogenic E. coliBRIGBLAST Ring Image GeneratorCCclonal complexCDScoding DNA sequenceCUchaperone usher pathway fimbriaeEAECenteroaggregative E. coliECORE. coli ReferenceECPE. coli common pilusEHECenterohaemorrhagic E. coliEPECenteropathogenic E. coliETECenterotoxigenic E. coliETT2E. coli type III secretion system 2ExPECextraintestinal pathogenic E. coliFecferric iron(III)-dicitrate uptake systemFFfitness factorFlag-1E. coli peritrichous flagella 1 gene clusterFlag-2E. coli lateral flagella 2 gene clusterG4Cgroup 4 capsuleGIgenomic islandGTRgeneralized time-reversibleHGThorizontal gene transferIPECintestinal pathogenic E. coliISinsertion sequenceLEElocus of enterocyte effacementLPSlipopolysaccharideMAECmastitis-associated E. coliMGEmobile genetic elementMLmaximum likelihoodMNECnewborn meningitis-associated E. coliMPECmammary pathogenic E. coliMSTminimum spanning treeNETneutrophil extracellular trapOGorthologous groupOMPouter membrane proteinORFopen reading framePAIpathogenicity islandPAMPpathogen-associated molecular patternPEpaired-endPHASTPHAge Search ToolPMNpolymorphonuclear neutrophilPTSphosphotransferase systemRhsrearrangement hotspotSLVsingle locus variantSPATEserine protease autotransporters of EnterobacteriaceaeSRASequence Read ArchiveSTsequence typeT2SStype II secretion systemT3SStype III secretion systemT5SStype V secretion systemT6SStype VI secretion systemTLRToll-like receptorUPECuropathogenic E. coliVFDBVirulence Factors DatabaseVFvirulence factorWGAwhole genome nucleotide alignment %U https://www.biorxiv.org/content/biorxiv/early/2016/12/23/096479.full.pdf