Phylogroup and lpfA influence epithelial invasion by mastitis associated Escherichia coli

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• 作者：Belgin Dogan ; Mark Rishniw ; Guillaume Bruant ; Josee Harel ; Ynte H. Schukken ; Kenneth W. Simpson
• 关键词：Escherichia coli ; Mastitis ; Virulence ; Long polar fimbriae ; Phylogroup
• 刊名：Veterinary Microbiology
• 出版年：2012
• 出版时间：14 September, 2012
• 年：2012
• 卷：159
• 期：1-2
• 页码：163-170
• 全文大小：423 K

文摘

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.