Enhanced detection of Taylorella equigenitalis by qPCR using ‘Dry’ swabs.

This study assesses the suitability of using ‘Dry’ swabs, swabs without transport medium, to detect the bacterium Taylorella equigenitalis in horses via PCR testing, in comparison to traditional swabs that use Amies charcoal transport medium. The findings conclude that ‘Dry’ swabs perform at least equivalently in this application, and may even be advantageous for routine sampling when culture is not being used.

Study Aim and Design

• The aim of this study was to determine if dry swabs, ones that are not placed in a transport medium after collection, can be as effective as Amies Charcoal transport medium based swabs for detecting Taylorella equigenitalis via PCR testing.
• The design of the experiment involved a factorial structure using both the type of swab and the dilution of organism in culture suspensions.
• Simulated genital swabs were prepared for the research by dipping them into a culture suspension containing T. equigenitalis along with other organisms, and then placed them inside a protective sleeve, either with or without transport medium. This was conducted in two stages.

Research Procedure and Techniques

• In the first part of the experiment, the researchers compared ‘cycle threshold’ (Ct value) differences between the two swab types.
• In the second part, they introduced genital swab material into the cultural suspensions and recompared the swab types.
• The researchers then tested the swabs using a validated quantitative PCR method. This method amplifies and quantifies DNA, thereby providing a measure of the presence and amount of T. equigenitalis in the sample.
• The Ct values of the PCR tests were used as the comparative measure. Effects of variables were assessed through linear regression.

Outcomes and Conclusion

• The study found that dry swabs had a 7.7% higher mean Ct value compared to the swabs in a transport medium. The difference was particularly evident at higher dilutions.
• The inclusion of genital swab material did not affect the Ct value.
• In conclusion, dry swabs are at least as effective for PCR detection of T. equigenitalis as transport medium-based swabs, especially with a relatively low number of organisms are present, hence advantageous for routine sampling when culture is not being used.