[Comparison of direct smear observations and bacteriologic culture results carried out on equine tracheal secretions].
Abstract: The aim of the study was to assess the relation between the direct smear observations and bacteriological results carried out on equine tracheal secretions. A total of 304 cases comprising both the direct smear (Gram stain) and the bacteriological culture, over a period of 8 years, were submitted to this retrospective study. Most of the specimens (78%) were obtained using tracheal washings while the rest (22%) originated from tracheal brushings. A total of 96 specimens (32%) were negative for both direct smear and culture. The positive predictive value of direct smears appeared high (81-96%) while the negative predictive value was lower (48-79%). Sensitivity of direct smear was considered as low and varied from 24 to 46% for tracheal brushings and from 41 to 46% for tracheal washings. Specificity of direct smear was high for both types of specimens. Results of this study indicate that the use of Gram-stained smear examination, carried out on tracheal secretions, is a technique which is specific but not very sensitive for the prediction of bacteriological culture results. Moreover, the use of tracheal washing, more than tracheal brushing, seems to increase the sensitivity of the test. The aim of the study was to assess the relation between the direct smear observations and bacteriological results carried out on equine tracheal secretions. A total of 304 cases comprising both the direct smear (Gram stain) and the bacteriological culture, over a period of 8 years, were submitted to this retrospective study. Most of the specimens (78%) were obtained using tracheal washings while the rest (22%) originated from tracheal brushings. A total of 96 specimens (32%) were negative for both direct smear and culture. The positive predictive value of direct smears appeared high (81-96%) while the negative predictive value was lower (48-79%). Sensitivity of direct smear was considered as low and varied from 24 to 46% for tracheal brushings and from 41 to 46% for tracheal washings. Specificity of direct smear was high for both types of specimens. Results of this study indicate that the use of Gram-stained smear examination, carried out on tracheal secretions, is a technique which is specific but not very sensitive for the prediction of bacteriological culture results. Moreover, the use of tracheal washing, more than tracheal brushing, seems to increase the sensitivity of the test.
Publication Date: 2001-08-25 PubMed ID: 11519272PubMed Central: PMC1476569
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- Comparative Study
- English Abstract
- Journal Article
Summary
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This research was conducted to determine the accuracy and efficacy of direct smear observations compared to bacteriological culture results, specifically focusing on equine tracheal secretions. The results indicate that Gram-stained smear examination of these secretions is specific, although not highly sensitive, to predict bacteriological culture results, with tracheal washing proving more effective than tracheal brushing.
Study Design and Methods
- The study analyzed 304 cases over an 8-year period which included both a Gram-stained smear examination (direct smear) and a bacteriological culture analysis.
- The majority (78%) of the specimens studied were obtained from tracheal washing, the remaining 22% came from tracheal brushing.
- This study is retrospective in nature meaning it looked back at already existing records to gather data.
Results and Findings
- The research found that 32% (96) of the total specimens returned negative results for both direct smears and culture testing.
- The positive predictive value (the probability that subjects with a positive screening test truly have the disease) of the direct smears was high, between 81% and 96%.
- Conversely, the negative predictive value (the probability that subjects with a negative screening test truly don’t have the disease) was much lower, ranging from 48% to 79%.
- Furthermore, the sensitivity (how accurately the test identifies positive outcomes) of the direct smear varied significantly – from just 24% to 46% for tracheal brushings and slightly higher for tracheal washings at 41% to 46%.
- However, the specificity (the ability of the test to correctly identify negative results) of the direct smear was high for both types of specimens.
Conclusions and Implications
- The results of this research indicate that using the Gram-stained smear examination method on tracheal secretions is a specific technique for predicting bacteriological culture results, but it lacks in sensitivity.
- The study also suggests more success in increasing test sensitivity with the use of tracheal washing instead of tracheal brushing.
- These findings are useful to inform future diagnostic procedures and techniques for equine respiratory diseases and can help improve the accuracy of diagnoses.
Cite This Article
APA
Labonville M, Higgins R, Lavoie JP.
(2001).
[Comparison of direct smear observations and bacteriologic culture results carried out on equine tracheal secretions].
Can Vet J, 42(8), 623-626.
Publication
Researcher Affiliations
- Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, C.P. 5000, Saint-Hyacinthe, Québec J2S 7C6.
MeSH Terms
- Animals
- Bacteriological Techniques / methods
- Bacteriological Techniques / veterinary
- Gentian Violet
- Horses / microbiology
- Phenazines
- Predictive Value of Tests
- Retrospective Studies
- Sensitivity and Specificity
- Specimen Handling / veterinary
- Trachea / microbiology
References
This article includes 8 references
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- Equine Vet J. 1990 May;22(3):170-3
- Am J Vet Res. 1993 Oct;54(10):1602-7
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