Pulsed-Field Gel Electrophoresis Genotyping of Taylorella equigenitalis Isolates Collected in the United States from 1978 to 2010

Abstract

Taylorella equigenitalis is the etiologic agent of contagious equine metritis (CEM), a venereal disease of horses. A total of 82 strains of T. equigenitalis isolated in the United States were analyzed by pulsed-field gel electrophoresis (PFGE) after digestion of genomic DNA with restriction enzyme ApaI. Twenty-eight of those strains isolated from horses in the 2009 U.S. outbreak (CEM09) were further analyzed with NotI and NaeI enzymes. When ApaI alone was used for analysis, the 82 isolates clustered into 15 different genotypes that clearly defined groups of horses with known epidemiological connections. The PFGE profiles of the CEM09 isolates were indistinguishable after digestion with ApaI, NotI, and NaeI and did not match those of isolates from previous U.S. outbreaks in 1978 and 2006 or of any other isolate from the National Veterinary Services Laboratories (NVSL) culture library. Coupled with the fact that the CEM09 isolates are epidemiologically related, these results suggest a common source for the outbreak not linked to previous occurrences of CEM in the United States.

Overview of spatio-temporal distribution inferred by multi-locus sequence typing of Taylorella equigenitalis isolated worldwide from 1977 to 2018 in equidae

“…CEM was first reported in 1977 in the United Kingdom and Ireland among Thoroughbred horses (Crowhurst, 1977;Timoney et al, 1977), but is currently a worldwide concern in various equine breeds (Jeoung et al, 2016;Schulman et al, 2013) with the hypothesis that the episodic "source of contagion" is often mainland Europe (Schulman et al, 2013). Pulsedfield gel electrophoresis (Aalsburg and Erdman, 2011;Sting et al, 2016) and several other molecular typing tools including field inversion gel electrophoresis (Bleumink-Pluym et al, 1990), chromosomal DNA fingerprinting (Thoresen et al, 1995), crossed-field gel electrophoresis (Miyazawa et al, 1995) and more recently repetitive extragenic palindromic PCR (Sting et al, 2016) have been used to genotype CEM isolates. However, these molecular epidemiological tools are not very portable and inter-laboratory results are difficult to compare (Maiden et al, 1998), making them ill-suited for global epidemiological studies of 5 CEM outbreaks.…”

Genomic diversity of Taylorella equigenitalis introduced into the United States from 1978 to 2012

“…Missed diagnoses of animals, especially those that are asymptomatic, leaves countries vulnerable to new introductions. These introductions pose a great risk for countries where the organism is not endemic, like the United States, and are key to the insidious movement of the organism throughout the world [ 3 , 4 , 6 ].…”

“…Further research showed that in all 109 Japanese isolates between 2 studies there was a single, identical electrophoresis pattern with pulsed-field gel-electrophoresis (PFGE), but these differed from strains originating in other parts of the world [ 9 , 10 ]. Despite these large groupings, PFGE provided the most distinguishing genetic characteristics among isolates for many years with studies showing as many as 17 groups in 82 isolates [ 6 ]. Other attempted methods, random amplified polymorphic DNA and amplified rDNA restriction analysis, made previously distinguishable isolates appear identical [ 11 ].…”

Polymerase chain reaction‐based national surveillance programme to determine the distribution and prevalence of Taylorella equigenitalis in South African horses

“…Taylorella equigenitalis is a nonmotile, microaerophilic Gram‐negative, frequently pleiomorphic bacterium that causes contagious equine metritis (CEM), a nonsystemic, venereally transmitted disease of horses. T. equigenitalis is spread directly during natural mating or artificial insemination (AI) with semen from a carrier stallion and by indirect fomite transmission . Affected stallions are unapparent carriers of the organism and are the principal source of infection.…”