Comparison of nasopharyngeal and guttural pouch specimens to determine the optimal sampling site to detect Streptococcus equi subsp equi carriers by DNA amplification.
Abstract: Streptococcus equi subsp equi (S. equi) is the cause of "equine strangles" which is a highly infectious upper respiratory disease. Detection of S. equi is influenced by site of specimen collection, method of sampling, and type of diagnostic test that is performed. We hypothesized i) that a loop-mediated isothermal amplification (LAMP) assay that targets the S. equi-specific eqbE gene would be more sensitive than a realtime PCR assay that targets the S. equi-specific seeI gene and ii) that LAMP of specimens obtained by guttural pouch lavage (GPL) would be more sensitive than LAMP of nasopharyngeal specimens to identify S. equi carriers. Methods: A nasopharyngeal flocked swab, nasopharyngeal wash, and GPL specimen was collected from 44 convalescent horses and the eqbE LAMP assay was performed. The seeI realtime PCR assay and aerobic culture were also performed on the GPL specimen. Logistic regression was performed to compare sampling sites and test methods (P-values ≤0.05 were considered significant). Results: One of 41 nasopharyngeal flocked swabs, 6/38 nasopharyngeal wash and 24/44 GPL specimens were positive by eqbE LAMP. 18/44 GPL specimens were positive by seeI PCR and S. equi was isolated from 4/44 of these specimens. Detection of S. equi DNA was 51 times more likely from the GPL samples than nasopharyngeal samples (OR 51.0, P < 0.0001). When eqbE LAMP GPL samples were positive, it was eight times more likely that the guttural pouch had any abnormality on endoscopy (OR 8.2, P ≤ 0.005), almost 20 times more likely that mild empyema was found (OR 19.7, P ≤ 0.002), and eight times more likely that the SeeI PCR was positive for S. equi DNA (OR 8.1, P ≤ 0.006). Conclusions: This study demonstrates that guttural pouch lavage specimens should be used to detect S. equi and that the eqbE LAMP assay was comparable to the seeI PCR.
Publication Date: 2017-03-23 PubMed ID: 28335829PubMed Central: PMC5364677DOI: 10.1186/s12917-017-0989-4Google Scholar: Lookup
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- Journal Article
Summary
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This research investigates the optimal method for detecting carriers of Streptococcus equi, the bacteria causing the equine respiratory illness known as strangles. The study posits that samplingguttural pouch lavage (GPL) using a loop-mediated isothermal amplification (LAMP) assay is more effective than typical nasopharyngeal swabbing methods.
Objective of the Research
The research aims to determine the most effective method for detecting Streptococcus equi subsp equi (S. equi), the bacterium responsible for “equine strangles,” an infectious respiratory disease in horses. The effectiveness of the detection method relies on the site of specimen collection, sampling method, and the type of diagnostic test performed. The researchers hypothesize that a particular type of gene-targeted assay would be more sensitive and that using samples obtained from the guttural pouch would yield more accurate results than those from nasopharyngeal swabs.
Methodology and Results
- Different types of samples were collected from 44 horses recovering from illness, namely nasopharyngeal swabs, nasopharyngeal washes, and guttural pouch lavages (GPL).
- The loop-mediated isothermal amplification (LAMP) assay was applied to these samples, targeting the eqbE gene sequence specific to S. equi.
- The seeI real-time PCR (polymerase chain reaction) assay and aerobic culture were also performed on the GPL specimens.
- Statistical analysis revealed that the S. equi DNA was 51 times more likely detected from the GPL samples than nasopharyngeal samples. Moreover, when the GPL samples were positive, it was found to increase the likelihood of detecting any abnormality on endoscopy, mild empyema, and positive results for S. equi DNA in the SeeI PCR test.
Conclusions
The study concludes that the most effective method to detect S. equi carriers is to use guttural pouch lavage specimens, and the eqbE LAMP assay is comparable to the seeI PCR in terms of effectiveness. This finding could significantly improve the detection of equine strangles carriers, paving the way for more effective control and prevention strategies for this highly infectious disease.
Cite This Article
APA
Boyle AG, Stefanovski D, Rankin SC.
(2017).
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, 13(1), 75.
https://doi.org/10.1186/s12917-017-0989-4 Publication
Researcher Affiliations
- Department of Clinical Studies New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, 382 West Street Rd, Kennett Square, PA, 19348, USA. boylea@vet.upenn.edu.
- Department of Clinical Studies New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, 382 West Street Rd, Kennett Square, PA, 19348, USA.
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, 3900 Spruce Street, Room 4036, Philadelphia, PA, 19104, USA.
MeSH Terms
- Animals
- Carrier State / diagnosis
- Carrier State / veterinary
- Horse Diseases / diagnosis
- Horse Diseases / microbiology
- Horses
- Lymphadenitis / microbiology
- Lymphadenitis / veterinary
- Nasopharynx / microbiology
- Nucleic Acid Amplification Techniques / veterinary
- Real-Time Polymerase Chain Reaction / veterinary
- Specimen Handling / veterinary
- Streptococcal Infections / diagnosis
- Streptococcal Infections / microbiology
- Streptococcal Infections / veterinary
- Streptococcus equi / isolation & purification
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