title: Comparison of sampling sites and laboratory diagnostic tests for S. equi subsp. equi in horses from confirmed strangles outbreaks.
abstract: BACKGROUND
  Strangles is a contagious equine-specific disease caused by Streptococcus equi subsp. equi. Unfortunately, detection of S. equi can fail in up to 40% of horses with strangles. Whereas recent molecular biologic methods and sampling techniques have improved recovery of S. equi optimal sampling methods and laboratory analyses remain ill-defined.
  
  
  OBJECTIVE
  To determine the yield of S. equi from horses with acute strangles in confirmed outbreaks by field-sampling methods subjected to culture and biochemical identification, and real-time PCR directly and after culture.
  
  
  METHODS
  Fifty-seven horses of varying breeds and ages from 8 strangles outbreaks.
  
  
  METHODS
  Prospective study. Culture with biochemical identification and real-time PCR directly, and from culture, were performed on nasal swabs, nasopharyngeal swabs, and nasopharyngeal lavages.
  
  
  RESULTS
  Real-time PCR directly from samples identified the highest number of infected horses, with 45/57 nasal swabs, 41/57 nasopharyngeal swabs, and 48/57 nasopharyngeal lavages S. equi positive. Biochemical identification (highest positives 22/57) was inferior to real-time PCR for S. equi recovery regardless of sampling method. Real-time PCR of nasopharyngeal lavage directly and after culture yielded 52/57 positives whereas direct real-time PCR of nasopharyngeal lavage combined with either nasopharyngeal swabs or nasal swabs yielded 53/57 positives. Three horses were negative on all samples.
  
  
  CONCLUSIONS
  Nasopharyngeal lavage analyzed by a combination of real-time PCR directly and after culture or, alternatively, real-time PCR directly on a nasopharyngeal lavage and a nasal/nasopharyngeal swab can identify S. equi in over 90% of acute strangles cases.
authors.affiliation: Section of Bacteriology, National Veterinary Institute, Uppsala, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Lindahl
authors.forename: V
authors.initials: V
authors.lastname: Båverud
authors.forename: A
authors.initials: A
authors.lastname: Egenvall
authors.forename: A
authors.initials: A
authors.lastname: Aspán
authors.forename: J
authors.initials: J
authors.lastname: Pringle
mesh_terms: D000818:Animals; D004196:Disease Outbreaks / Q000662:veterinary*; D006734:Horse Diseases / Q000453:epidemiology / Q000382:microbiology*; D006736:Horses; D009305:Nasopharynx / Q000382:microbiology; D009666:Nose / Q000382:microbiology; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D013290:Streptococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D018502:Streptococcus equi / Q000302:isolation & purification*