Date of Award
Master of Science
Veterinary Microbiology and Preventive Medicine
The objective of this study was to develop an improved selective medium for the isolation of Taylorella sp. It is important the United States remains free of contagious equine metritis, because large sums of money could be lost in the Thoroughbred industry if this organism is not easily detected. The currently used selective medium, Modified Timoney Shin (MTS), is too restrictive for growing some strains of Taylorella sp. A new selective media that is more restrictive to growth of contaminants would ensure that laboratory personnel are able to isolate Taylorella sp. more readily from diagnostic samples. A total of eighty-seven antimicrobials were evaluated using a disk diffusion test, and ten antimicrobials with the smallest mean zones of inhibition for Taylorella sp. over three replications were chosen for inclusion in this study. The zones of inhibition of Taylorella equigenitalis strains were significantly larger than the zones of inhibition of Taylorella asinigenitalis strains for some of the antimicrobials. Combinations of antimicrobials were evaluated, and final selections were based on the maximum number of contaminants inhibited and on the ability to support the growth of T. equigenitalis and T. asinigenitalis. The combination of 320 [mu]g/ml p-aminosalicyclic acid, 5 [mu]g/ml clindamycin, and 5 [mu]g/ml amphotericin B supported the growth of Taylorella sp., but was more inhibitory to the ten most frequent contaminants than was MTS. Ten individual contaminants and sixteen combinations of a single dilution of contaminants with Taylorella sp. included in lower dilutions were plated onto the new medium and MTS. Fourteen contaminants were more inhibited on the new medium than on MTS, eleven had comparable growth on both, and there was one that grew better on the new medium. Twenty-two swabs from caudal reproductive tracts of horses were evaluated. Sixteen had less growth on the new medium than on MTS, four had comparable growth, and two had more growth. A side by side comparison of the new media with MTS will be necessary to evaluate its potential to replace MTS in diagnostic testing.
Ann Michelle Carew
Carew, Ann Michelle, "The development of a new selective medium for isolation of Taylorella sp." (2003). Retrospective Theses and Dissertations. 17508.