Pathogenicity and virulence of Rhodococcus equi in foals following intratracheal challenge.
Twelve foals, between 27 and 83 days old, were infected with 2 strains of Rhodococcus equi by intratracheal administration. Ten of the 12 foals were inoculated with 10(4)-10(10) colony forming units (cfu) of ATCC 33701 strain. The other 2 foals were inoculated with 10(9) cfu of a plasmid-cured derivative of the ATCC 33701 strain (ATCC 33701P-). All of the 10 foals challenged with the ATCC 33701 strain showed clinical signs of pulmonary disease within 5-13 days, such as gross lesions associated with acute bronchopneumonia and microscopic lesions associated with granulomatous pneumonia. The two foals challenged with the ATCC 33701P- strain showed neither clinical signs of disease nor gross lesions. Apparently, when lacking plasmid, the virulent Rhodococcus equi lost its pathogenicity.
Wada
R
R
Epizootic Research Station, Equine Research Institute, Japan Racing Association, Tochigi, Japan. wada@epizoo.equinst.go.jp
Kamada
M
M
Anzai
T
T
Nakanishi
A
A
Kanemaru
T
T
Takai
S
S
Tsubaki
S
S
D000193:Actinomycetales Infections / Q000473:pathology / Q000503:physiopathology / Q000662:veterinary*; D000818:Animals; D001831:Body Temperature; D006099:Granuloma / Q000382:microbiology / Q000473:pathology / Q000662:veterinary; D006734:Horse Diseases; D006736:Horses; D008168:Lung / Q000382:microbiology / Q000473:pathology*; D008171:Lung Diseases / Q000382:microbiology / Q000473:pathology / Q000662:veterinary; D008264:Macrophages / Q000382:microbiology; D018410:Pneumonia, Bacterial / Q000473:pathology / Q000503:physiopathology / Q000662:veterinary*; D016929:Rhodococcus equi / Q000145:classification / Q000302:isolation & purification / Q000472:pathogenicity*; D013045:Species Specificity; D013997:Time Factors; D014132:Trachea; D014774:Virulence