The value of spectrofluorometry for the diagnosis of contagious equine metritis.

This research investigated the reliability of spectrofluorimetry as a diagnostic tool for contagious equine metritis (CEM), an equine infection. While the method showed some promise, with an 81% success rate in current CEM tests, its overall reliability was limited due to a number of false results, also found in tests on unrelated bacterial species and complex culture media.

Objective of the Research

• The aim of the study was to explore the efficacy of a spectrofluorimetric assay for diagnosing contagious equine metritis (CEM), a sexually transmitted infection in horses. The effectiveness of the method was tested using vaginal discharges from mares, both from those tested positive and negative for CEM.

Method and Results of Spectrofluorimetric Assay

• The researchers conducted the spectrofluorimetric assay by exciting neutral aqueous extracts of CEM-positive discharges at 265 nm, which produced emission spectra that peaked at 350 nm and 460 nm.
• Using the 460 nm peak as an indicator, 81% of the positive and negative CEM samples were correctly identified. However, there was one false negative and two false positive results, indicating some scope of error with this method.
• The researchers further tested this method on six “high risk” animals (those with higher chances of contracting CEM), all of which tested positive.

Application of Spectrofluorimetry on Unknown Discharges

• This method was then applied to 26 “unknown” discharges, where the success rate dropped to 65%, with three false negatives and six false positives.
• The same process when applied to 14 bacterial species that were unrelated to CEM and three forms of complex culture media, produced similar fluorescence and chromatographic properties. This meant that the method tested positive for materials that did not have CEM, reducing its efficacy as a reliable diagnostic tool.

Conclusion

• The study concluded that while spectrofluorimetry showed some potential in identifying CEM, its overall reliability was limited due to a substantial rate of false results. The method also returned positive results for unrelated bacteria and culture mediums, further denting its validity as a standalone diagnostic tool for CEM.