Genotypic characterization of VapA positive Rhodococcus equi in foals with pulmonary affection and their soil environment on a warmblood horse breeding farm in Germany.

The research article is about studying the genetic patterns of a bacteria called Rhodococcus equi, which causes pneumonia, from horses and the environment where they live, and how the disease could spread in a horse breeding farm in Germany.

Objective and Methodology of the Research

• The study was conducted to identify the genotypic characterization of a bacteria named Rhodococcus equi, which shows a specific protein called VapA and causes lung diseases in foals.
• Researchers used a procedure called pulsed-field gel electrophoresis for genotypic characterization. It allows scientists to separate large DNA molecules by size.
• Nasal and tracheal samples were collected from 217 foals showing signs of pneumonia or pulmonary abscesses, along with soil samples from their environment in a warmblood horse breeding farm in Germany.

Findings from the Clinical Samples

• In their study, they found Rhodococcus equi in more than half of the tracheal samples (54% or 118 out of 217) and almost a quarter of the nasal samples (24% or 52 out of 217).
• They determined the prevalence of VapA protein in the bacteria collected from these samples through a technique called an enzyme-linked immunosorbent assay. In most of the selected nasal swabs (68% or 26 out of 37) and tracheal samples (73% or 40 out of 55), the VapA protein was present.

Findings from the Environmental Samples

• R. equi was found in a high proportion of the soil samples taken in March (87% or 56 out of 64) and July (68% or 17 out of 25) in 2003.
• Some of these soil bacteria also tested VapA-positive: 21% (3 out of 14) from the March samples and considerably more, 81% (13 out of 16), from the July samples.

Genotypic Characterization of VapA Positive Strains

• The VapA positive strains from the foals and the soil samples underwent plasmid profiling, which further characterizes the genetic information of bacteria, and restriction fragment length polymorphism analysis, which can identify variations within the genetic sequence.
• Most of the analyzed isolates (80 out of 83) contained an 85-kb type I plasmid, a small, separately replicating DNA molecule.
• The pulsed-field gel electrophoresis results showed that these isolates fall into four distinct VspI profiles, which classified them into three major and three minor groups.

Conclusion of the Study

• The results indicate that most foals were exposed to and infected with three main groups of this bacteria containing an 85-kb type I plasmid.
• This understanding can offer insights into the control and prevention of VapA positive R. equi infections in horse breeding farms.