Molecular epidemiologic features of Corynebacterium pseudotuberculosis isolated from horses.
OBJECTIVE
To characterize isolates of Corynebacterium pseudotuberculosis from horses, cattle, and sheep in Colorado, Kentucky, Utah, and California in samples collected during perceived epidemics of infection (increased numbers of cases identified) in 2002 and 2003, and determine how closely isolates were related and their possible source.


METHODS
54 isolates of C pseudotuberculosis from 49 horses, 4 cattle, and 1 sheep.


METHODS
Random amplified polymorphic DNA (RAPD) polymerase chain reaction (PCR) assay, PCR assay for the gene encoding the phospholipase D (PLD) toxin, biochemical analyses, and tests for susceptibility to 17 antimicrobial drugs were performed.


RESULTS
All isolates reduced nitrate to nitrite, most yielded positive results for the PLD toxin gene, and all were susceptible to antimicrobial drugs. Ten genetic types were detected by use of RAPD PCR assay; types III to X were isolated from horses, cattle, or both in 1 or more states. Types III and IX were isolated from both horses and cattle. Types VII and VIII were isolated in only 1 state, but the number of isolates in these groups was small. In contrast, all other types were isolated in 2 or more states. All isolates from Utah were type III, but the other 3 states had isolates from more than 1 type.


CONCLUSIONS
These data are consistent with a clonally expanding epidemic of infection in Utah and an increase in number of infections caused by multiple strains of C pseudotuberculosis not derived from a single source in the other states. The increase in number of infections could be the result of reporting bias, environmental factors facilitating infection, or host factors such as greater herd susceptibility.
Foley
Janet E
JE
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Spier
Sharon J
SJ
Mihalyi
Judy
J
Drazenovich
Niki
N
Leutenegger
Christian M
CM
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology*; D003354:Corynebacterium Infections / Q000453:epidemiology / Q000662:veterinary*; D016925:Corynebacterium pseudotuberculosis / Q000235:genetics* / Q000302:isolation & purification*; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004352:Drug Resistance, Microbial; D005838:Genotype; D006734:Horse Diseases / Q000453:epidemiology / Q000382:microbiology*; D006736:Horses; D017720:Molecular Epidemiology; D010739:Phospholipase D / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000662:veterinary; D019105:Random Amplified Polymorphic DNA Technique / Q000662:veterinary; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology / Q000382:microbiology*; D014481:United States / Q000453:epidemiology
D004269:DNA, Bacterial; D010739:Phospholipase D