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Abstract

Pulsed field gel electrophoresis of restriction endonuclease digested genomic DNA from a collection of clinical isolates of Rhodococcus equi was used to compare strain diversity on different Thoroughbred horse farms over time. Restricted diversity was found among the isolates tested, as the same strains were detected on multiple farms and in multiple years. Marked variation occurred in strain prevalence with some strains being represented by single isolates, and the most prevalent by 26 isolates. There were dominant strains on some farms and the prevalence of some strains differed between farms. Infection with multiple strains was noted in some cases where multiple isolates from a single foal were examined.

Strain-to-strain variation of Rhodococcus equi growth and biofilm formation in vitro

“…Several genotypically distinct isolates of R. equi have been obtained from soil, air, water, and feces at horse breeding farms [12, 13], but the majority of studies to date have been conducted using a few relatively well characterized strains [2, 7, 14, 15]. The advantage to this approach is reproducibility among studies and the ability to build on previous work.…”

Molecular characterization of Rhodococcus equi isolates from horses in Poland: pVapA characteristics and plasmid new variant, 85-kb type V

“…During the study we detected chromosomal variability among some of investigated isolates what had been previously described even among isolates collected from the same farm [ 26 , 33 , 34 ]. However, these studies were performed on a high number of isolates from heterogeneous horse populations with numerous clinical cases and soil samples from many farms contrary to our study conducted on smaller farms that stay in contact, for example by exchange of the horses.…”

Epidemiologic study of results of pulsed-field gel electrophoresis of isolates of Rhodococcus equi obtained from horses and horse farms

“…These findings are similar to the genotypic diversity of R equi isolates from Australia. 22,23 Guidelines for molecular epidemiologic characterization of strains by use of PFGE indicate that strain characterization should only be applied to small sets of isolates related to potential outbreaks. 28 In the study reported here, isolates from the same farm met these criteria for strain characterization.…”

“…19 Serologic groupings and examination of plasmid patterns, however, are not as discriminating as genetic fingerprinting (genotyping) techniques such as pulsed-field gel electrophoresis (PFGE) of restriction endonuclease-digested genomic DNA. 20 In a few studies, [21][22][23] investigators have used PFGE to evaluate isolates of R equi obtained from horses. Differences in PFGE patterns among 21 European isolates of R equi from feces of healthy cattle and horses have been documented as well as variability within and among farms.…”

“…21 The PFGE analysis of R equi isolates obtained from Thoroughbred horse farms in Australia has been reported. 22,23 Analysis of those studies indicates that a large number of PFGE-defined strains of R equi exists, that individual farms tend to have particular strains, and that there is considerable heterogeneity in PFGE patterns among isolates. To the authors' knowledge, use of PFGE to compare a large (≥ 30) number of isolates from various continents or from the United States has not been reported.…”