A real-time PCR assay for the quantification of Mycoplasma equirhinis in tracheal wash samples from Thoroughbred horses.

This research paper presents a method, called quantitative real-time PCR (qPCR), used to measure the amount of Mycoplasma equirhinis bacteria in tracheal wash samples of horses. By using this method, the researchers found that some horses with cough symptoms had significantly higher amounts of this bacteria, pointing to a likely link between the bacteria and the health condition in these horses.

Objective and Introduction

• The researchers sought to establish a better method to measure the quantity of Mycoplasma equirhinis, a common equine bacteria species, in horses.
• This bacteria is often found in clinically normal horses but is suspected to be connected to inflammatory airway diseases where coughing is the predominant symptom.
• Previously, accurately assessing the amount of this bacteria in samples was difficult due to the use of conventional culture methods that required pre-enrichment with liquid cultures.

Methodology

• They developed a quantitative real-time PCR (qPCR) assay, which is a method to amplify and simultaneously monitor the levels of a specific DNA molecule, to quantify this bacteria.
• They targeted a specific hypothetical protein, FJM08_00025, to confirm the high species-specificity for Mycoplasma equirhinis and a limit of detection of 2.9 copies per reaction.

Key Findings

• Using this method, they were able to measure the levels of Mycoplasma equirhinis in tracheal wash samples from 20 clinically normal horses and 22 coughing horses.
• The copy numbers of Mycoplasma equirhinis detected in 18 of the 22 samples from coughing horses were within the range detected in clinically normal horses.
• However, four samples had significantly higher copy numbers, up to 1,620,000 copies per reaction, suggesting a potential link between the infection by this bacteria and the coughing symptoms.

Conclusion

• The qPCR assay allows a more accurate and simpler assessment of Mycoplasma equirhinis infection compared to traditional culture methods.
• This method could be a beneficial tool in diagnosing coughing horses and helping establish a stronger connection between the coughing symptom and this specific bacteria species infection.