Comparison of nasopharyngeal and guttural pouch specimens to determine the optimal sampling site to detect Streptococcus equi subsp equi carriers by DNA amplification.

Authors: Boyle Ashley G, Stefanovski Darko, Rankin Shelley C

Journal: BMC veterinary research

DOI: 10.1186/s12917-017-0989-4 PubMed: 28335829Log in to save

Summary

# Editorial Summary Streptococcus equi subspecies equi, the causative agent of strangles, presents significant diagnostic challenges because detection varies substantially depending on where and how samples are collected. Boyle and colleagues compared two molecular amplification techniques (loop-mediated isothermal amplification targeting the eqbE gene versus real-time PCR targeting the seeI gene) across two sampling sites (nasopharyngeal swabs and guttural pouch lavage fluid) to identify the most reliable method for identifying carrier horses. The guttural pouch lavage specimens detected S. equi more frequently than nasopharyngeal samples when analysed by LAMP, and LAMP itself showed superior sensitivity compared to PCR across both collection sites. For practitioners involved in strangles management and biosecurity protocols, these findings suggest that guttural pouch lavage combined with LAMP-based detection offers the highest probability of identifying carrier animals, which has important implications for quarantine decisions and infection control in yards where strangles status remains uncertain.

Read the full abstract on PubMed

Practical Takeaways

•If screening for S. equi carriers, guttural pouch lavage appears superior to nasopharyngeal swabbing for detection, reducing risk of missed carriers in your facility
•Choice of molecular assay (LAMP vs PCR) affects detection sensitivity; confirm your diagnostic lab's methodology when screening horses
•Optimal sampling protocol is critical—single nasopharyngeal swabs may miss carriers, so consider guttural pouch sampling for definitive carrier status in high-risk situations

Key Findings

•LAMP assay targeting eqbE gene compared against real-time PCR assay targeting seeI gene for S. equi detection
•Guttural pouch lavage specimens evaluated against nasopharyngeal specimens for optimal carrier detection
•Sampling site and diagnostic methodology influence sensitivity of S. equi detection in carrier horses

Conditions Studied

streptococcus equi subsp equi carrier detectionequine stranglesupper respiratory disease

Related References

Detection of Streptococcus equi subsp. equi in guttural pouch lavage samples using a loop-mediated isothermal nucleic acid amplification microfluidic device.

Boyle Ashley G, Rankin Shelley C, O'Shea Kathleen, Stefanovski Darko, Peng Jing, Song Jinzhao, Bau Haim H(2021)Journal of veterinary internal medicine

Evaluation of a nested PCR test and bacterial culture of swabs from the nasal passages and from abscesses in relation to diagnosis of Streptococcus equi infection (strangles).

Grønbaek L Møller, Angen O, Vigre H, Olsen S Nautrup(2006)Equine veterinary journal

Effectiveness of a screening protocol employed at a UK rescue centre to prevent introduction of strangles.

McLinden Luke A, Kemp-Symonds Jeremy G, Daly Janet M, Blanchard Adam M, Waller Andrew S, Freeman Sarah L(2026)Equine veterinary journal

Development of a real-time PCR to detect Streptococcus equi subspecies equi.

North S E, Wakeley P R, Mayo N, Mayers J, Sawyer J(2014)Equine veterinary journal

Optimization of Conditions for The Multiplex PCR for Diagnostics of Horse Strangles with Subspecies Differentiation of Streptococcus Equi Subsp Equi

Berdimuratova K.T., Makhamed R., Shevtsov A.B.(2020)Eurasian Journal of Applied Biotechnology