Pooling of genital swabs for detection by PCR of Taylorella equigenitalis, the cause of contagious equine metritis

I. Mawhinney, J. Errington, N. Stamper, N. Torrens, M.Y. Engelsma, H.I.J. Roest

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)

Abstract

Background: Sets of genital swabs are routinely taken from horses to screen for the presence of Taylorella equigenitalis, the cause of contagious equine metritis. Typically, two to four different sites are swabbed at a time and tested by culture or PCR. Objectives: This study explored the feasibility of pooling these swabs for a single PCR test per animal instead of testing each swab individually. Study design: In vitro. Methods: PCR signal strengths (Ct values) from 149 historical PCR positive genital swabs, together with historical data on the number of swabs in a set expected to be positive, were used to assess the suitability of pooling for screening horses for T. equigenitalis infection in the population at large. Twenty-four sets of four equine genital swabs were tested. The sets were prepared in the laboratory using one or more swabs positive for T. equigenitalis from naturally infected cases. Positive and negative swabs were selected to reflect a typical range of PCR Ct values expected in field cases of T. equigenitalis infection. These pools were tested by an established PCR to assess the impact and suitability of a PCR test on pooled swabs compared to individual swab testing, by comparing the Ct values. Results: Pooling one positive swab with three negative swabs produced a small drop in Ct value but all pools were still clearly positive. Main limitations: Large numbers of field positive horses are not available, but the proof of concept approach with laboratory prepared pools shows the method is applicable to field cases. Conclusions: It was concluded that pooling of swabs would confer no appreciable drop in the ability to detect a positive animal compared to individual swab testing; pooling is therefore a suitable alternative to individual swab testing with reduced costs. The Summary is available in Spanish – see Supporting Information.

LanguageEnglish
Pages227-230
JournalEquine Veterinary Journal
Volume51
Issue number2
DOIs
Publication statusPublished - Mar 2019

Fingerprint

Taylorella equigenitalis
contagious equine metritis
Horses
genitalia
Polymerase Chain Reaction
horses
testing
infection
Feasibility Studies
Infection
animals
experimental design
screening
Costs and Cost Analysis

Keywords

  • diagnosis
  • horse
  • infection
  • validation

Cite this

@article{f00c97be59464c6db7751339c25f0bcd,
title = "Pooling of genital swabs for detection by PCR of Taylorella equigenitalis, the cause of contagious equine metritis",
abstract = "Background: Sets of genital swabs are routinely taken from horses to screen for the presence of Taylorella equigenitalis, the cause of contagious equine metritis. Typically, two to four different sites are swabbed at a time and tested by culture or PCR. Objectives: This study explored the feasibility of pooling these swabs for a single PCR test per animal instead of testing each swab individually. Study design: In vitro. Methods: PCR signal strengths (Ct values) from 149 historical PCR positive genital swabs, together with historical data on the number of swabs in a set expected to be positive, were used to assess the suitability of pooling for screening horses for T. equigenitalis infection in the population at large. Twenty-four sets of four equine genital swabs were tested. The sets were prepared in the laboratory using one or more swabs positive for T. equigenitalis from naturally infected cases. Positive and negative swabs were selected to reflect a typical range of PCR Ct values expected in field cases of T. equigenitalis infection. These pools were tested by an established PCR to assess the impact and suitability of a PCR test on pooled swabs compared to individual swab testing, by comparing the Ct values. Results: Pooling one positive swab with three negative swabs produced a small drop in Ct value but all pools were still clearly positive. Main limitations: Large numbers of field positive horses are not available, but the proof of concept approach with laboratory prepared pools shows the method is applicable to field cases. Conclusions: It was concluded that pooling of swabs would confer no appreciable drop in the ability to detect a positive animal compared to individual swab testing; pooling is therefore a suitable alternative to individual swab testing with reduced costs. The Summary is available in Spanish – see Supporting Information.",
keywords = "diagnosis, horse, infection, validation",
author = "I. Mawhinney and J. Errington and N. Stamper and N. Torrens and M.Y. Engelsma and H.I.J. Roest",
year = "2019",
month = "3",
doi = "10.1111/evj.12986",
language = "English",
volume = "51",
pages = "227--230",
journal = "Equine Veterinary Journal",
issn = "0425-1644",
publisher = "Wiley",
number = "2",

}

Pooling of genital swabs for detection by PCR of Taylorella equigenitalis, the cause of contagious equine metritis. / Mawhinney, I.; Errington, J.; Stamper, N.; Torrens, N.; Engelsma, M.Y.; Roest, H.I.J.

In: Equine Veterinary Journal, Vol. 51, No. 2, 03.2019, p. 227-230.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Pooling of genital swabs for detection by PCR of Taylorella equigenitalis, the cause of contagious equine metritis

AU - Mawhinney, I.

AU - Errington, J.

AU - Stamper, N.

AU - Torrens, N.

AU - Engelsma, M.Y.

AU - Roest, H.I.J.

PY - 2019/3

Y1 - 2019/3

N2 - Background: Sets of genital swabs are routinely taken from horses to screen for the presence of Taylorella equigenitalis, the cause of contagious equine metritis. Typically, two to four different sites are swabbed at a time and tested by culture or PCR. Objectives: This study explored the feasibility of pooling these swabs for a single PCR test per animal instead of testing each swab individually. Study design: In vitro. Methods: PCR signal strengths (Ct values) from 149 historical PCR positive genital swabs, together with historical data on the number of swabs in a set expected to be positive, were used to assess the suitability of pooling for screening horses for T. equigenitalis infection in the population at large. Twenty-four sets of four equine genital swabs were tested. The sets were prepared in the laboratory using one or more swabs positive for T. equigenitalis from naturally infected cases. Positive and negative swabs were selected to reflect a typical range of PCR Ct values expected in field cases of T. equigenitalis infection. These pools were tested by an established PCR to assess the impact and suitability of a PCR test on pooled swabs compared to individual swab testing, by comparing the Ct values. Results: Pooling one positive swab with three negative swabs produced a small drop in Ct value but all pools were still clearly positive. Main limitations: Large numbers of field positive horses are not available, but the proof of concept approach with laboratory prepared pools shows the method is applicable to field cases. Conclusions: It was concluded that pooling of swabs would confer no appreciable drop in the ability to detect a positive animal compared to individual swab testing; pooling is therefore a suitable alternative to individual swab testing with reduced costs. The Summary is available in Spanish – see Supporting Information.

AB - Background: Sets of genital swabs are routinely taken from horses to screen for the presence of Taylorella equigenitalis, the cause of contagious equine metritis. Typically, two to four different sites are swabbed at a time and tested by culture or PCR. Objectives: This study explored the feasibility of pooling these swabs for a single PCR test per animal instead of testing each swab individually. Study design: In vitro. Methods: PCR signal strengths (Ct values) from 149 historical PCR positive genital swabs, together with historical data on the number of swabs in a set expected to be positive, were used to assess the suitability of pooling for screening horses for T. equigenitalis infection in the population at large. Twenty-four sets of four equine genital swabs were tested. The sets were prepared in the laboratory using one or more swabs positive for T. equigenitalis from naturally infected cases. Positive and negative swabs were selected to reflect a typical range of PCR Ct values expected in field cases of T. equigenitalis infection. These pools were tested by an established PCR to assess the impact and suitability of a PCR test on pooled swabs compared to individual swab testing, by comparing the Ct values. Results: Pooling one positive swab with three negative swabs produced a small drop in Ct value but all pools were still clearly positive. Main limitations: Large numbers of field positive horses are not available, but the proof of concept approach with laboratory prepared pools shows the method is applicable to field cases. Conclusions: It was concluded that pooling of swabs would confer no appreciable drop in the ability to detect a positive animal compared to individual swab testing; pooling is therefore a suitable alternative to individual swab testing with reduced costs. The Summary is available in Spanish – see Supporting Information.

KW - diagnosis

KW - horse

KW - infection

KW - validation

U2 - 10.1111/evj.12986

DO - 10.1111/evj.12986

M3 - Article

VL - 51

SP - 227

EP - 230

JO - Equine Veterinary Journal

T2 - Equine Veterinary Journal

JF - Equine Veterinary Journal

SN - 0425-1644

IS - 2

ER -