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Home / Equine Research Bank / J Vet Intern Med / Estimating the Sensitivity and Specificity of Real-Time Quan...
Journal of veterinary internal medicine2015; 29(6); 1712-1717; doi: 10.1111/jvim.13631

Estimating the Sensitivity and Specificity of Real-Time Quantitative PCR of Fecal Samples for Diagnosis of Rhodococcus equi Pneumonia in Foals.

Abstract: Real-time, quantitative PCR (qPCR) methods for detecting Rhodococcus equi in feces have been developed as a noninvasive, rapid diagnostic test for R. equi pneumonia, but have not been evaluated in a large population of foals. Objective: The objective of this study was to evaluate the clinical utility of fecal PCR as a diagnostic test for R. equi pneumonia in foals using receiver operating characteristic (ROC) methods. Methods: 186 foals born in 2011 at an R. equi-endemic ranch in Texas. Methods: Fecal samples were collected at the time of onset of clinical signs for pneumonic foals (n = 31). Foals with pneumonia were matched by age and birth date to healthy (n = 31) and subclinical (n = 124) control foals; fecal samples were collected from these controls. DNA was extracted from feces using commercial kits and concentration of virulent R. equi in feces was determined by qPCR. Results: Concentration of R. equi in feces differed significantly (P < .05) among groups. The area under the ROC curve for fecal qPCR for diagnosis of R. equi pneumonia was 89% (95% CI, 83-99), with a sensitivity of 94% and specificity of 72%. Conclusions: qPCR of feces can be useful as an alternative to tracheobronchial aspiration for the diagnosis of R. equi in foals with clinical signs of pneumonia. Caution should be used in extrapolating results of this study to other populations because fecal concentration of R. equi might vary by geographic location or management practices.
Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.
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Publication Date: 2015-10-05 PubMed ID: 26436545PubMed Central: PMC4895660DOI: 10.1111/jvim.13631Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't

Summary

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The research article evaluates the effectiveness of a non-invasive, rapid diagnostic technique involving real-time quantitative PCR (qPCR) of fecal samples for the diagnosis of Rhodococcus equi pneumonia in foals. The method was tested in a large population of foals and found to have 94% sensitivity and 72% specificity, suggesting its potential as a reliable alternative to more invasive methods.

Study Objective and Methods

  • The main goal of the study was to understand the efficacy of using fecal PCR as a diagnostic tool for Rhodococcus equi pneumonia in foals. To achieve this purpose, the researchers used Receiver Operating Characteristic (ROC) methods.
  • The study involved 186 foals born in 2011 at a Rhodococcus equi-endemic ranch in Texas. These were divided into foals exhibiting signs of pneumonia (31 in number), healthy ones (31), and subclinical foals (124).
  • Fecal samples were taken from all foals at the onset of clinical signs for those with pneumonia symptoms. The sick foals were age and birth date matched with the healthy and subclinical groups.
  • DNA was then extracted from these fecal samples using commercial kits, and a qPCR analysis was performed to determine the concentration of the virulent Rhodococcus equi bacteria in their feces.

Results of the Research

  • Analysis of the data showed a significant difference in the concentration of Rhodococcus equi in the feces of the different groups of foals.
  • The ROC curve demonstrated a value of 89% for fecal qPCR diagnosis of Rhodococcus equi pneumonia, which was within the confidence interval of 83-99%.
  • The test demonstrated a sensitivity of 94%, indicating a high chance of identifying true positives, and a specificity of 72%, suggesting a considerable ability to identify true negatives.

Conclusions Drawn From the Study

  • The study concluded that the qPCR of fecal samples can serve as an alternative to tracheobronchial aspiration for diagnosing Rhodococcus equi in foals with pneumonia symptoms.
  • However, the researchers also cautioned that these results may not be applicable to foals from different regions or under different management practices as their fecal concentration of Rhodococcus equi might vary.

Cite This Article

APA
Shaw SD, Cohen ND, Chaffin MK, Blodgett GP, Syndergaard M, Hurych D. (2015). Estimating the Sensitivity and Specificity of Real-Time Quantitative PCR of Fecal Samples for Diagnosis of Rhodococcus equi Pneumonia in Foals. J Vet Intern Med, 29(6), 1712-1717. https://doi.org/10.1111/jvim.13631

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 29
Issue: 6
Pages: 1712-1717

Researcher Affiliations

Shaw, S D
  • Department of Large Animal Clinical Sciences, College of Biomedical Sciences and Veterinary Medicine, Texas A&M University, College Station, TX.
Cohen, N D
  • Department of Large Animal Clinical Sciences, College of Biomedical Sciences and Veterinary Medicine, Texas A&M University, College Station, TX.
Chaffin, M K
  • Department of Large Animal Clinical Sciences, College of Biomedical Sciences and Veterinary Medicine, Texas A&M University, College Station, TX.
Blodgett, G P
  • 6666 Ranch, Guthrie, TX.
Syndergaard, M
  • 6666 Ranch, Guthrie, TX.
Hurych, D
  • Department of Large Animal Clinical Sciences, College of Biomedical Sciences and Veterinary Medicine, Texas A&M University, College Station, TX.

MeSH Terms

  • Actinomycetales Infections / diagnosis
  • Actinomycetales Infections / epidemiology
  • Actinomycetales Infections / microbiology
  • Actinomycetales Infections / veterinary
  • Animals
  • Feces / microbiology
  • Horse Diseases / diagnosis
  • Horse Diseases / microbiology
  • Horses
  • Pneumonia, Bacterial / diagnosis
  • Pneumonia, Bacterial / epidemiology
  • Pneumonia, Bacterial / microbiology
  • Pneumonia, Bacterial / veterinary
  • Real-Time Polymerase Chain Reaction
  • Rhodococcus equi / isolation & purification
  • Sensitivity and Specificity
  • Texas / epidemiology

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