title: Experimental infection of mice with Rhodococcus equi: differences in virulence between strains.
abstract: The growth kinetics in outbred mice of clinical and environmental isolates of Rhodococcus equi were followed by serial bacterial enumeration of organ homogenates. Clinical isolates multiplied until Day 4 before being progressively cleared, but could still be recovered from the liver at 3-4 weeks post-infection. Intravenous inoculation of clinical strains was associated with histopathological responses very similar to those elicited by intravenous infection with various facultative intracellular parasites. Whereas lesions in mice and foals at 7-9 days following respiratory infection are those of severe bronchopneumonia with massive consolidation, a week later the patterns of host response have diverged as the murine lesions resolve. The type strain, NCTC 1621 and 4-6 environmental isolates were eliminated without prior multiplication and these strains caused negligible lesions. The two environmental strains which behaved as the clinical strains were recovered from a stud with an R. equi problem. No association of colonial morphology of R. equi with virulence was apparent.
authors: Department of Veterinary Pathology and Public Health, University of Queensland, St. Lucia, Australia.
authors: P M
authors: PM
authors: Bowles
authors: J B
authors: JB
authors: Woolcock
authors: M D
authors: MD
authors: Mutimer
mesh_terms: D000193:Actinomycetales Infections / Q000473:pathology*; D000818:Animals; D005260:Female; D008099:Liver / Q000382:microbiology / Q000473:pathology; D008168:Lung / Q000382:microbiology / Q000473:pathology; D051379:Mice; D012240:Rhodococcus / Q000472:pathogenicity*; D013045:Species Specificity; D013154:Spleen / Q000382:microbiology / Q000473:pathology; D014774:Virulence