Streptococcus equi Detection Polymerase Chain Reaction Assay for Equine Nasopharyngeal and Guttural Pouch Wash Samples.
Abstract: Bacterial culture and polymerase chain reaction (PCR) assays for the detection of Streptococcus equi in nasopharyngeal washes (NPW) and guttural pouch lavage (GPL) samples have low sensitivity. In human diagnostics, processing of samples with flocked swabs has improved recovery rates of bacterial agents because of improved surface area and elution factors. Objective: For S. equi subsp. equi (S. equi) detection in NPW and GPL samples we hypothesized that: direct-PCR would be more reliable than flocked swab culture (FS culture); flocked swab PCR (FS-PCR) would be equivalent to direct-PCR; and FS culture would be more reliable than traditional culture. Methods: A total of 193 samples (134 NPW and 59 GPL) from 113 horses with either suspected S. equi infection, convalescing from a known S. equi infection, or asymptomatic horses screened for S. equi. Methods: Prospective study. Samples were submitted for S. equi direct-PCR. Using logistic regression, direct-PCR (gold standard) was compared to FS culture, traditional culture, and FS-PCR also performed. Results: Direct-PCR was statistically more sensitive than FS-PCR, FS culture, and traditional culture (P < .001). All methods had sensitivities <70% relative to the direct-PCR. FS culture had a similar sensitivity relative to traditional culture. The odds of GPL samples being positive on direct-PCR (P = .030) and FS-PCR were greater than those for NPW samples (P = .021). Conclusions: Use of flocked swabs during laboratory preprocessing did not improve detection of S. equi via either PCR or bacterial culture from samples. Direct-PCR is the preferred method of detection of S. equi.
Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.
Publication Date: 2015-12-17 PubMed ID: 26678318PubMed Central: PMC4913660DOI: 10.1111/jvim.13808Google Scholar: Lookup
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- Journal Article
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Summary
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The research article is about the comparison of different methods for detecting the bacterial species Streptococcus equi in horse samples. The researchers found that direct-polymerase chain reaction (PCR) is the most effective method for this purpose.
Objective and Hypotheses
The primary goal of the study was to compare the effectiveness of various methods in detecting Streptococcus equi subspecies equi (S.equi), a bacterium present in the nasopharyngeal washes (NPW) and guttural pouch lavage (GPL) samples of horses. The authors proposed three hypotheses:
- Direct-PCR would be a more reliable detection method than flocked swab culture (FS culture).
- Flocked swab PCR (FS-PCR) would be equivalent to direct-PCR.
- FS culture would be more reliable than traditional bacterial culture.
Methods
The research involved a total of 193 samples collected from 113 horses. These horses were those suspected of having an S.equi infection, recovering from such an infection, or asymptomatic horses screened for the presence of S.equi. The study was prospective in nature. The samples were sent for direct-PCR testing, and the results were compared to FS culture, traditional culture, and FS-PCR.
Results
The findings revealed that direct-PCR was notably more sensitive than FS-PCR, FS culture, and traditional culture, making it the most effective method among those tested. All methods had sensitivities of less than 70% relative to direct-PCR. Furthermore, FS culture and traditional culture methods had similar levels of sensitivity. In terms of sample types, the odds of getting a positive result from direct-PCR and FS-PCR were higher for GPL samples as compared to NPW samples.
Conclusions
The study concluded that using flocked swabs in the lab preprocessing did not enhance the detection of S. equi in either PCR or bacterial culture from samples. Hence, direct-PCR was favored as a more reliable method for the detection of S.equi in the samples as compared to FS-PCR, FS culture, and traditional culture.
Cite This Article
APA
Boyle AG, Rankin SC, D￮ L, Boston RC, Wheeler-Aceto H.
(2015).
Streptococcus equi Detection Polymerase Chain Reaction Assay for Equine Nasopharyngeal and Guttural Pouch Wash Samples.
J Vet Intern Med, 30(1), 276-281.
https://doi.org/10.1111/jvim.13808 Publication
Researcher Affiliations
- Department of Clinical Studies New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, 19348.
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, 19348.
- Department of Clinical Studies New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, 19348.
- Department of Clinical Studies New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, 19348.
- Department of Clinical Studies New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, 19348.
MeSH Terms
- Animals
- Female
- Horse Diseases / diagnosis
- Horse Diseases / microbiology
- Horses
- Male
- Nasopharynx / microbiology
- Polymerase Chain Reaction / methods
- Streptococcal Infections / diagnosis
- Streptococcal Infections / microbiology
- Streptococcal Infections / veterinary
- Streptococcus equi / isolation & purification
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Citations
This article has been cited 11 times.- Seeger MG, de Vargas APC, Vogel FSF, Cargnelutti JF. Streptococcus equi subsp. equi isolated from horses in Southern Brazil: molecular and phenotypic analyses. Braz J Microbiol 2025 Dec;56(4):2987-2996.
- Zu H, Sun R, Li J, Guo X, Wang M, Guo W, Wang X. Integrated CRISPR-Cas12a and RAA one-pot visual strategy for the rapid identification of Streptococcus equi subspecies equi. Front Cell Infect Microbiol 2025;15:1526516.
- Iduu NV, Raiford D, Cohen ND, Landrock KK, Wang C. High-resolution melting curve FRET-qPCR rapidly distinguishes Streptococcus equi subsp. equi and zooepidemicus. Microbiol Spectr 2025 Sep 2;13(9):e0152925.
- Weese JS, Saab M, Moore A, Cai H, McClure JT. Relationship between quantitative real-time PCR cycle threshold and culture for detection of Streptococcus equi subspecies equi. Can Vet J 2023 Jun;64(6):549-552.
- Nadruz V, Beard LA, Delph-Miller KM, Larson RL, Bai J, Chengappa MM. Efficacy of high-level disinfection of endoscopes contaminated with Streptococcus equi subspecies equi with 2 different disinfectants. J Vet Intern Med 2023 Jul-Aug;37(4):1561-1567.
- Brankston G, Rossi TM, O'Sullivan TL, Greer AL. Diagnostic testing patterns for Streptococcus equi subsp. equi in Ontario horses during the years 2008 to 2018. Can Vet J 2021 Jun;62(6):629-636.
- Boyle AG, Rankin SC, O'Shea K, Stefanovski D, Peng J, Song J, Bau HH. Detection of Streptococcus equi subsp. equi in guttural pouch lavage samples using a loop-mediated isothermal nucleic acid amplification microfluidic device. J Vet Intern Med 2021 May;35(3):1597-1603.
- Smith FL, Watson JL, Spier SJ, Kilcoyne I, Mapes S, Sonder C, Pusterla N. Frequency of shedding of respiratory pathogens in horses recently imported to the United States. J Vet Intern Med 2018 Jul;32(4):1436-1441.
- Boyle AG, Timoney JF, Newton JR, Hines MT, Waller AS, Buchanan BR. Streptococcus equi Infections in Horses: Guidelines for Treatment, Control, and Prevention of Strangles-Revised Consensus Statement. J Vet Intern Med 2018 Mar;32(2):633-647.
- Boyle AG, Rankin SC, Duffee LA, Morris D. Prevalence of Methicillin-Resistant Staphylococcus aureus from Equine Nasopharyngeal and Guttural Pouch Wash Samples. J Vet Intern Med 2017 Sep;31(5):1551-1555.
- Boyle AG, Stefanovski D, Rankin SC. Comparison of nasopharyngeal and guttural pouch specimens to determine the optimal sampling site to detect Streptococcus equi subsp equi carriers by DNA amplification. BMC Vet Res 2017 Mar 23;13(1):75.
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