Survey and Sequence Characterization of Bovine Mastitis-Associated Escherichia coli in Dairy Herds

Abstract

Escherichia coli is frequently associated with mastitis in cattle. “Pathogenic” and “commensal” isolates appear to be genetically similar. With a few exceptions, no notable genotypic differences have been found between commensal and mastitis-associated E. coli. In this study, 24 E. coli strains were isolated from dairy cows with clinical mastitis in three geographic regions of Australia (North Queensland, South Queensland, and Victoria), sequenced, then genomically surveyed. There was no observed relationship between sequence type (ST) and region (p = 0.51). The most common Multi Locus Sequence Type was ST10 (38%), then ST4429 (13%). Pangenomic analysis revealed a soft-core genome of 3,463 genes, including genes associated with antibiotic resistance, chemotaxis, motility, adhesion, biofilm formation, and pili. A total of 36 different plasmids were identified and generally found to have local distributions (p = 0.02). Only 2 plasmids contained antibiotic resistance genes, a p1303_5-like plasmid encoding multidrug-resistance (trimethoprim, quaternary ammonium, beta-lactam, streptomycin, sulfonamide, and kanamycin) from two North Queensland isolates on the same farm, while three Victorian isolates from the same farm contained a pCFSAN004177P_01-like plasmid encoding tetracycline-resistance. This pattern is consistent with a local spread of antibiotic resistance through plasmids of bovine mastitis cases. Notably, co-occurrence of plasmids containing virulence factors/antibiotic resistance with putative mobilization was rare, though the multidrug resistant p1303_5-like plasmid was predicted to be conjugative and is of some concern. This survey has provided greater understanding of antibiotic resistance within E. coli-associated bovine mastitis which will allow greater prediction and improved decision making in disease management.

The epidemiology of AmpC-producing Escherichia coli isolated from dairy cattle faeces on pasture-fed farms

“…coli and mastitis associated E. coli has occurred; however as with our study no metadata was collected to explain the pathway of transmission, for example, through movement of cattle from one farm to another [14, 44].…”

Sequence characterisation and novel insights into bovine mastitis-associated Streptococcus uberis in dairy herds

“…Herd selection was based on ease of access to the farm location and the cooperation of the dairy farm owners and their associated veterinary practices. Detailed methodology is described elsewhere 101 . Briefly, milk samples were collected from eligible dairy cows with a new case of clinical mastitis.…”

Unveiling distinct genetic features in multidrug-resistant Escherichia coli isolated from mammary tissue and gut of mastitis induced mice

“…This study has predicted the sequence type, evolutionary phylogeny, ARGs, VFGs, and genomic metabolic potentials of the isolates of E. coli from MT and FS. The findings of our research shed light on genetic relatedness of E. coli which is known as a predominant pathogen in mammalian mastitis [ 16 , 23 , 62 , 66 , 67 ].…”

“…Our investigation of the genomes also revealed the presence of three CRISPR arrays in each genome harboring 12 signature genes. CRISPR arrays, which have been identified in many bacterial pathogens (including E. coli ) causing mastitis, play a significant role in host adaptive immune response and virulence [ 66 ]. The genomic data from this study showed that the E. coli isolate from MT (G2M6U strain) was genetically distinct from the one from FS (G6M1F strain) in murine mastitis.…”