Towards an understanding of Salmonella enterica serovar Typhimurium persistence in swine.

Salmonella enterica is an important food borne pathogen that is frequently carried by swine. Carrier animals pose a food safety risk because they can transmit S. enterica to finished food products in the processing plant or by contamination of the environment.

Characterization and differential gene expression between two phenotypic phase variants in Salmonella enterica serovar Typhimurium.

Salmonella enterica serovar Typhimurium strain 798 has previously been shown to undergo phenotypic phase variation. One of the phenotypes expresses virulence traits such as adhesion, while the other phenotype does not. Phenotypic phase variation appears to correlate with the ability of this strain to cause persistent, asymptomatic infections of swine.

Evaluation of a commercially available modified-live Streptococcus equi subsp equi vaccine in ponies.

Objective: To evaluate a commercially available modified-live Streptococcus equi subsp equi vaccine for safety and persistence in vaccinated ponies and to detect recombination or reversion events in the vaccine strain.

Animals: 5 ponies that were 1.5 to 8 years old (group 1) and 4 ponies that were 6 months old (group 2).

A multiphasic typing approach to subtype Streptococcus equi subspecies equi.

The objective of the present investigation was to differentiate between strains of Streptococcus equi subspecies equi implicated in abscess formation in vaccinated horses. Streptococcus equi isolates recovered from clinical specimens associated with equine strangles cases submitted to the University of Illinois Veterinary Diagnostic Laboratory were compared with S. equi isolates representing at least 12 lots of a commercial modified live vaccine (MLV) to determine whether the isolates obtained from the abscesses were vaccine or wild type.

Effects of therapeutic ceftiofur administration to dairy cattle on Escherichia coli dynamics in the intestinal tract.

The goal of this study was to follow ceftiofur-treated and untreated cattle in a normally functioning dairy to examine enteric Escherichia coli for changes in antibiotic resistance profiles and genetic diversity. Prior to treatment, all of the bacteria cultured from the cows were susceptible to ceftiofur. Ceftiofur-resistant E.

Development of a polymerase chain reaction assay for the detection of antibiotic resistance genes in community DNA.

Many methods are used to detect antibiotic resistance genes in samples. The objective of the study reported here was to compare polymerase chain reaction (PCR) analysis of community DNA with fecal culturing for detecting antibiotic resistance genes in cattle samples. In the laboratory-based portion of this study, known concentrations of an Escherichia coli strain with 3 antibiotic resistance genes (cmy-2, flo, and cat) were added to feces from dairy cattle.

Relationship between phenotypic and genotypic florfenicol resistance in Escherichia coli.

This study evaluated the relationship between florfenicol resistance and flo genotypes in 1,987 Escherichia coli isolates from cattle. The flo gene was detected in 164 isolates, all of which expressed resistance to florfenicol at MICs of >/=256 microg/ml. The florfenicol MICs for all isolates that lacked flo were View Article and Find Full Text PDF