Relationship of Mixed Bacterial Infection to Prognosis in Foals with Pneumonia Caused by Rhodococcus equi
Article first published online: 1 NOV 2012
Copyright © 2012 by the American College of Veterinary Internal Medicine
Journal of Veterinary Internal Medicine
Volume 26, Issue 6, pages 1443–1448, November/December 2012
How to Cite
Giguère, S., Jordan, L.M.I., Glass, K. and Cohen, N.D. (2012), Relationship of Mixed Bacterial Infection to Prognosis in Foals with Pneumonia Caused by Rhodococcus equi. Journal of Veterinary Internal Medicine, 26: 1443–1448. doi: 10.1111/j.1939-1676.2012.01023.x
- Issue published online: 20 NOV 2012
- Article first published online: 1 NOV 2012
- Manuscript Accepted: 10 SEP 2012
- Manuscript Revised: 8 AUG 2012
- Manuscript Received: 30 APR 2012
- Tracheobronchial aspirate
Isolation of multiple bacterial species is common in foals with Rhodococcus equi pneumonia.
There is no association between isolation of other microorganisms and outcome.
155 foals with pneumonia caused by R. equi.
Case records of foals diagnosed with R. equi pneumonia based on culture of the respiratory tract were reviewed at 2 referral hospitals (University of Florida [UF] and Texas A&M University [TAMU]).
R. equi was cultured from a tracheobronchial aspirate (TBA) in 115 foals and from lung tissue in 38 foals. Survival was significantly higher at UF (71%; 70/99) than at TAMU (50%; 28/56). R. equi was significantly more likely to grow in pure cultures from samples obtained from foals at UF (55%; 54/99) than from foals at TAMU (23%; 13/56). Microorganisms cultured with R. equi included Gram-positive bacteria in 40, Gram-negative bacteria in 41, and fungi in 23 foals. The most common bacteria isolated were beta-hemolytic streptococci (n = 26) and Escherichia coli (n = 18). Mixed infections were significantly more likely to be encountered in TBA than in lung tissue. Only foals from which R. equi was cultured from a TBA were included in the analysis for association between mixed infection and outcome. After adjusting for the effect of hospital using multivariate logistic regression, mixed culture, mixed bacterial culture, Gram-positive bacteria, beta-hemolytic streptococci, Gram-negative bacteria, enteric Gram-negative bacteria, nonenteric Gram-negative bacteria, and fungi were not significantly associated with outcome.
Conclusions and Clinical Importance
Isolation of multiple bacteria or fungi from a TBA along with R. equi does not negatively impact prognosis.