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Journal of clinical microbiology2001; 39(4); 1289-1293; doi: 10.1128/JCM.39.4.1289-1293.2001

Comparison of nucleic acid amplification, serology, and microbiologic culture for diagnosis of Rhodococcus equi pneumonia in foals.

Abstract: Recently, a technique was described for amplification of Rhodococcus equi-specific chromosomal and vapA DNA from blood and tracheal wash fluids. It was hypothesized that this technique would be more sensitive than standard culture techniques or serology for diagnosis of R. equi pneumonia in foals. Tracheal wash fluid, nasal swabs, whole blood samples, and serum samples from 56 foals with pneumonia were analyzed. Final clinical diagnosis was determined by the attending clinician on the basis of final interpretation of all available information about each foal, including clinical presentation, diagnostic test results, response to therapy, and outcome. Clinical diagnosis was used as a final reference standard for calculation of sensitivity, specificity, and predictive values for PCR, serology using an agar gel immunodiffusion test, and tracheal wash fluid culture. PCR of tracheal wash fluid using primers that recognized the vapA virulence plasmid of R. equi had a diagnostic sensitivity of 100% and specificity of 90.6%. Sensitivity and specificity were 57.1 and 93.8%, respectively, for standard microbiologic culture of tracheal wash fluid and 62.5 and 75.9%, respectively, for serology. PCR of tracheal wash fluid is more sensitive and specific for diagnosis of R. equi pneumonia than are other available diagnostic tests.
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Publication Date: 2001-04-03 PubMed ID: 11283043PubMed Central: PMC87926DOI: 10.1128/JCM.39.4.1289-1293.2001Google Scholar: Lookup
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  • Comparative Study
  • Evaluation Study
  • Journal Article
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  • Non-U.S. Gov't
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  • U.S. Gov't
  • Non-P.H.S.

Summary

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The research paper discusses the comparison of nucleic acid amplification, serology, and microbiologic culture in diagnosing Rhodococcus equi pneumonia in foals. The authors concluded that PCR of tracheal wash fluid was more sensitive and specific in diagnosing the disease than other available diagnostic methods.

Analysis of Diagnostic Techniques

  • This study compares three different diagnostic methods used to identify Rhodococcus equi pneumonia in foals. These methods include nucleic acid amplification through Polymerase Chain Reaction (PCR), serological tests, and microbiological culture.
  • Nucleic acid amplification with PCR involved the amplification of R. equi-specific chromosomal and vapA DNA. VapA is a virulence-associated protein found in R. equi bacterium that is integral to its association with disease in foals.
  • Serological testing using an agar gel immunodiffusion test and standard microbiological culture of tracheal wash fluid were the other two diagnostic approaches being compared in this study.

Diagnostic Method Comparison

  • The study used tracheal wash fluid, nasal swabs, whole blood samples, and serum samples from 56 foals with pneumonia for analysis. These samples allowed the researchers to compare the effectiveness of serology, PCR, and microbiological culture techniques in diagnosing R. equi pneumonia in foals.
  • The final diagnosis for each foal was established by the attending clinician, considering all the available information related to each foal’s clinical presentation, diagnostic test results, response to therapy, and outcome.

Findings of the Study and their Significance

  • The study’s findings indicated that PCR of tracheal wash fluid with primers that recognized the vapA virulence plasmid of R. equi was the most effective diagnostic technique among the three.
  • Its diagnostic sensitivity and specificity were 100% and 90.6% respectively, making it the most sensitive and specific approach for diagnosing R. equi pneumonia in foals.
  • In contrast, the sensitivity and specificity of standard microbiological culture of tracheal wash fluid were 57.1% and 93.8%, respectively. Serology demonstrated a sensitivity and specificity of 62.5% and 75.9%, respectively.
  • The implication of these findings is that PCR of tracheal wash fluid is superior to other available diagnostic tests for accurate detection of R. equi pneumonia in foals, with faster detection times and less false positive results.

Cite This Article

APA
Sellon DC, Besser TE, Vivrette SL, McConnico RS. (2001). Comparison of nucleic acid amplification, serology, and microbiologic culture for diagnosis of Rhodococcus equi pneumonia in foals. J Clin Microbiol, 39(4), 1289-1293. https://doi.org/10.1128/JCM.39.4.1289-1293.2001

Publication

Journal of clinical microbiology
ISSN: 0095-1137
NlmUniqueID: 7505564
Country: United States
Language: English
Volume: 39
Issue: 4
Pages: 1289-1293

Researcher Affiliations

Sellon, D C
  • Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, Washington 99164, USA. dsellon@vetmed.wsu.edu
Besser, T E
    Vivrette, S L
      McConnico, R S

        MeSH Terms

        • Actinomycetales Infections / diagnosis
        • Actinomycetales Infections / microbiology
        • Actinomycetales Infections / veterinary
        • Animals
        • Culture Media
        • DNA, Bacterial / analysis
        • Gene Amplification
        • Horse Diseases / diagnosis
        • Horse Diseases / microbiology
        • Horses
        • Immunodiffusion / methods
        • Pneumonia, Bacterial / diagnosis
        • Pneumonia, Bacterial / microbiology
        • Pneumonia, Bacterial / veterinary
        • Polymerase Chain Reaction / methods
        • Rhodococcus equi / genetics
        • Rhodococcus equi / immunology
        • Rhodococcus equi / isolation & purification
        • Sensitivity and Specificity

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