title: Use of Serial Quantitative PCR of the vapA Gene of Rhodococcus equi in Feces for Early Detection of R. equi Pneumonia in Foals.
abstract: BACKGROUND
  Current screening tests for Rhodococcus equi pneumonia in foals lack adequate accuracy for clinical use. Real-time, quantitative PCR (qPCR) for virulent R. equi in feces has not been systematically evaluated as a screening test.
  
  
  OBJECTIVE
  The objective of this study was to evaluate the accuracy of qPCR for vapA in serially collected fecal samples as a screening test for R. equi pneumonia in foals.
  
  
  METHODS
  One hundred and twenty-five foals born in 2011 at a ranch in Texas.
  
  
  METHODS
  Fecal samples were collected concurrently with thoracic ultrasonography (TUS) screening examinations at ages 3, 5, and 7 weeks. Affected (pneumonic) foals (n = 25) were matched by age and date-of-birth to unaffected (n = 25) and subclinical (ie, having thoracic TUS lesions but no clinical signs of pneumonia) foals (n = 75). DNA was extracted from feces using commercial kits and concentration of virulent R. equi in feces was determined by qPCR.
  
  
  RESULTS
  Subsequently affected foals had significantly greater concentrations of vapA in feces than foals that did not develop pneumonia (unaffected and subclinical foals) at 5 and 7 weeks of age. Accuracy of fecal qPCR, however, was poor as a screening test to differentiate foals that would develop clinical signs of pneumonia from those that would remain free of clinical signs (including foals with subclinical pulmonary lesions attributed to R. equi) using receiver operating characteristic (ROC) methods.
  
  
  CONCLUSIONS
  In the population studied, serial qPCR on feces lacked adequate accuracy as a screening test for clinical R. equi foal pneumonia.
authors.affiliation: Department of Large Animal Clinical Sciences, College of Biomedical Sciences and Veterinary Medicine, Texas A&M University, College Station, TX.
authors.forename: R G
authors.initials: RG
authors.lastname: Madrigal
authors.affiliation: Department of Large Animal Clinical Sciences, College of Biomedical Sciences and Veterinary Medicine, Texas A&M University, College Station, TX.
authors.forename: S D
authors.initials: SD
authors.lastname: Shaw
authors.affiliation: Laboratory of Veterinary Epidemiology and Economics, Faculty of Veterinary Medicine, Warsaw University of Life Sciences, Warsaw, Poland.
authors.forename: L A
authors.initials: LA
authors.lastname: Witkowski
authors.affiliation: Department of Large Animal Clinical Sciences, College of Biomedical Sciences and Veterinary Medicine, Texas A&M University, College Station, TX.
authors.forename: B E
authors.initials: BE
authors.lastname: Sisson
authors.affiliation: Equine Division, 6666 Ranch, Guthrie, TX.
authors.forename: G P
authors.initials: GP
authors.lastname: Blodgett
authors.affiliation: Department of Large Animal Clinical Sciences, College of Biomedical Sciences and Veterinary Medicine, Texas A&M University, College Station, TX.
authors.forename: M K
authors.initials: MK
authors.lastname: Chaffin
authors.affiliation: Department of Large Animal Clinical Sciences, College of Biomedical Sciences and Veterinary Medicine, Texas A&M University, College Station, TX.
authors.forename: N D
authors.initials: ND
authors.lastname: Cohen
mesh_terms: D000193:Actinomycetales Infections / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary; D000818:Animals; D001426:Bacterial Proteins / Q000302:isolation & purification*; D005243:Feces / Q000382:microbiology*; D006734:Horse Diseases / Q000175:diagnosis / Q000382:microbiology*; D006736:Horses; D018410:Pneumonia, Bacterial / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D016133:Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary*; D016929:Rhodococcus equi / Q000302:isolation & purification*; D012680:Sensitivity and Specificity
chemical_list: D001426:Bacterial Proteins; C541879:VapA protein, Rhodococcus equi
keywords: Feces; Horse; Pneumonia; Rhodococcus equi