High prevalence of <i>Mycoplasma equirhinis</i> in Thoroughbred horses with respiratory symptoms in autumn 2018

Detection of Mycoplasma spp. in horses with respiratory disorders

“…In the routine workflow at LAB EO, We then managed to identify 86% of the rt-PCR-positive samples and 100% of the isolated strains down to species level. Consistent with two previous studies, 17,18 the commonest species detected was M. equirhinis, representing 98% of the isolated strains and 85% of the rt-PCR-positive DNA. The proportion of the two non-horse-specific species was very low, with only 4 positive DNAs and one isolated strain for M. felis and one positive DNA for M. pulmonis.…”

“…23 Here we ran a detailed analysis of its specificity, sensitivity, and Ct cut-off for interpretation on three target Mycoplasma species already described in horses, that is., M. equirhinis, M. pulmonis, and M. felis. 14,[16][17][18] This genus-specific rt-PCR assay was run in duplex with an M. felis-specific rt-PCR assay targeting the tuf gene adapted from previous work. 24 By extending the probe by four bases in the 3 0 extremity, we were able to modify the acceptable cut-off for positivity to 37 in our experimental setup versus 35 in Söderlund et al 24 Preenrichment for 4 days in a Mycoplasma growth culture medium of spiked TW before DNA extraction and rt-PCR was shown to improve the sensitivity of the method by a factor of four for M. equirhinis, although the effect was more limited for M. felis and M. pulmonis (due to different growth capacity in our broth medium, data not shown).…”

“…15 From that day on, there have been regular reports of M. felis and M. equirhinis but not M. pulmonis, nor M. fastidiosum 16,17 in the respiratory tract of horses in various countries, but their clinical significance remains unclear. 18 The difficulty in specifying the aetiological role of these bacteria is partly due to the lack of systematic detection during diagnostic investigation and the absence of characteristic clinical signs. For instance, M. felis, a recognised cat pathogen, was suspected to be involved in pericarditis and/or pleuritis of horses, as it was isolated from pleural fluid in which no other bacterial species were detected.…”

“…Unfortunately, we cannot reasonably compare this prevalence figure with other datasets from different countries due to differences in experimental designs and detection methods. [16][17][18]22 Furthermore, we have no details concerning the Mycoplasma species present.…”

Mycoplasmas as Host Pantropic and Specific Pathogens: Clinical Implications, Gene Transfer, Virulence Factors, and Future Perspectives

“…equirhinis was isolated from 10.2% of tracheal wash samples from racehorses in Great Britain (Cardwell et al, 2013) and 16.2% from thoroughbred horses in Turkey (Mete and ÖZGÜR, 2017). More recently, using the loop-mediated isothermal amplification (LAMP) assay, M. equirhinis was isolated from 40.0% of Japanese horses (Uchida-Fujii et al, 2021).…”