title: Phylogroup and lpfA influence epithelial invasion by mastitis associated Escherichia coli.
abstract: Escherichia coli infection is one of the most common causes of bovine mastitis in well managed dairies. Although E. coli infections are usually transient, E. coli can also cause persistent intramammary infections. We sought to determine whether E. coli isolates recovered from either transient or persistent intramammary infections differed both genetically and in their ability to invade mammary epithelial cells. E. coli isolates from transient (EC(trans), n=16) and persistent (EC(pers), n=12) mastitis cases were compared for differences in overall genotype, virulence genes, serotype, phylogroup (A, B1, B2, D), and invasion of bovine mammary epithelial cells, MAC-T by microarray analysis, suppressive subtractive hybridization, PCR and gentamicin protection assays. EC(trans) and EC(pers) were diverse in overall genotype and serotype, and were predominantly of phylogroups A and B1. Both EC(trans) and EC(pers) contained genes encoding type II, IV and VI secretion systems, long polar fimbriae (lpfA) and iron acquisition, and lacked genes associated with virulence in diarrheagenic E. coli. EC(trans) had fewer virulence genes than EC(pers) (p<0.05), but no individual virulence genes were unique to either group. In phylogroup A, EC(pers) were more invasive than EC(trans) (p<0.05), but no difference was observed between them in phylogroup B1. Enhanced epithelial cell invasion was associated with lpfA (p<0.05). Our findings indicate that a genetically diverse group of E. coli is associated with transient and persistent mastitis. We did not identify a set of bacterial genes to account for phenotypic differences. However, we found that mastitis phenotype, phylogroup and presence of lpfA were associated with the ability to invade cultured bovine mammary epithelial cells.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA. be16@cornell.edu
authors.forename: Belgin
authors.initials: B
authors.lastname: Dogan
authors.forename: Mark
authors.initials: M
authors.lastname: Rishniw
authors.forename: Guillaume
authors.initials: G
authors.lastname: Bruant
authors.forename: Josee
authors.initials: J
authors.lastname: Harel
authors.forename: Ynte H
authors.initials: YH
authors.lastname: Schukken
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Simpson
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000382:microbiology*; D004926:Escherichia coli / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism* / Q000472:pathogenicity; D004927:Escherichia coli Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism*; D014644:Genetic Variation; D005838:Genotype; D008414:Mastitis, Bovine / Q000382:microbiology*; D020411:Oligonucleotide Array Sequence Analysis; D012703:Serotyping; D014774:Virulence / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C571199:LpfA1 protein, E coli; D036781:Fimbriae Proteins