Evaluation of MALDI-TOF MS and an expanded custom reference spectra database for the identification and differentiation of Taylorella equigenitalis and Taylorella asinigenitalis.

This research aims to evaluate the effectiveness of a particular mass spectrometry method, specifically MALDI-TOF MS, in differentiating between two similar bacterial species, Taylorella equigenitalis and Taylorella asinigenitalis, which are often confused in current testing methods. The researchers suggest expanding commercial databases with reference spectra to improve the method’s effectiveness.

Background and Objectives

• The bacterial species Taylorella equigenitalis is known to cause contagious equine metritis, a serious equine disease. Its close relative, Taylorella asinigenitalis, is often mistaken for it in diagnostic tests.
• A standard diagnostic tool, known as the gold standard culture method, struggles to differentiate these two species. This could lead to misdiagnoses and ineffective treatment plans.
• The aim of this study was to evaluate whether matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) could more effectively identify and distinguish between these two species.

Methods and Results

• The researchers used 85 strains of T. equigenitalis and 28 strains of T. asinigenitalis, selected based on multilocus sequence typing data, to test MALDI-TOF MS’s effectiveness.
• They also generated in-house reference spectra for both species using seven of the T. equigenitalis strains and nine of the T. asinigenitalis strains. This was to supplement the existent commercial Bruker database, with the aim of improving the method’s accuracy.
• Two different bacterial incubation times and three distinct sample preparation procedures were compared to determine the most efficient and accurate method.
• In their results, they showed that MALDI-TOF MS has potential as a differential diagnostic tool for contagious equine metritis, though the commercial spectra databases would need to include more T. asinigenitalis reference spectra for best performance.

Significance and Recommendations

• This study shows that the MALDI-TOF MS method can effectively differentiate between these two closely related bacterial species. This could lead to more accurate and effective diagnosis and, consequently, treatment of contagious equine metritis.
• However, the researchers also found that the direct spotting of 48-hour colonies was the most straightforward and efficient protocol, suggesting that this should be implemented in clinical settings for best results.