The prevalence, incidence, geographical distribution, antimicrobial sensitivity patterns and plasmid profiles of milk filter Salmonella isolates from Ontario dairy farms.

The prevalence, incidence and geographical distribution of Salmonella on dairy farms in southwestern Ontario were determined by culturing bulk milk filters from 511 randomly selected dairy farms. Milk filters from 22 farms (2.9%) were Salmonella-positive, with a cumulative incidence rate of 9.0% per year. Positive farms were distributed throughout southwestern Ontario, but were regionally clustered. The serotype, biotype, antimicrobial sensitivity pattern and plasmid profile of the Salmonella isolates from six farms where Salmonella were recovered on two occasions were identical. All of the Salmonella strains isolated were sensitive to commonly used antimicrobials.