Evaluation of nasotracheal aspiration as a diagnostic tool for Rhodococcusequi pneumonia in foals

The reliability of preparing bacteriological cultures from nasotracheal asp irates of foals routinely in order to diagnose R. Equi pneumonia in foals w as studied by isolating Rhodococcus equi from specimens obtained from 96 fo als by nasotracheal aspiration with a silicon catheter. Results were compar ed with specimens obtained from 21 foals by transtracheal aspiration (percu taneous tracheal puncture). These 117 foals showed clinical signs of respir atory tract infection at sampling, R. equi was isolated from 14 of 21 (66.7 %) specimens by transtracheal aspiration and from 59 of 96 (66.7%) specimen s by nasotracheal aspiration, 649 of 655 isolates (99.1%) from the 73 posit ive specimens mere virulent R. equi, and the culture-positive foals were di agnosed as having R. equi pneumonia. To assess the contamination of aspirat es by organisms from the nasopharynx, the results of R. equi isolation from nasal swabs obtained from 56 of the 96 foals were compared to those obtain ed by nasotracheal aspiration from the same foals. R. equi was isolated fro m 2 of the 56 nasal swabs: one from a tracheal aspirate was positive. and t he other was not. These results suggest that the nasotracheal aspiration te chnique, which is noninvasive and not associated with complications, could be used as an alternative to the transtracheal aspiration method, especiall y for the diagnosis of R. equi pneumonia in foals.