Association of soil concentrations of Rhodococcus equi and incidence of pneumonia attributable to Rhodococcus equi in foals on farms in central Kentucky.
OBJECTIVE
To determine whether soil concentrations of total or virulent Rhodococcus equi differed among breeding farms with and without foals with pneumonia caused by R equi.


METHODS
37 farms in central Kentucky. Procedures-During January, March, and July 2006, the total concentration of R equi and concentration of virulent R equi were determined by use of quantitative bacteriologic culture and a colony immunoblot technique, respectively, in soil specimens obtained from farms. Differences in concentrations and proportion of virulent isolates within and among time points were compared among farms.


RESULTS
Soil concentrations of total or virulent R equi did not vary among farms at any time point. Virulent R equi were identified in soil samples from all farms. Greater density of mares and foals was significantly associated with farms having foals with pneumonia attributable to R equi. Among farms with affected foals, there was a significant association of increased incidence of pneumonia attributable to R equi with an increase in the proportion of virulent bacteria between samples collected in March and July.


CONCLUSIONS
Results indicated that virulent R equi were commonly recovered from soil of horse breeding farms in central Kentucky, regardless of the status of foals with pneumonia attributable to R equi on each farm. The incidence of foals with pneumonia attributable to R equi can be expected to be higher at farms with a greater density of mares and foals.
Cohen
Noah D
ND
Department of Large Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA.
Carter
Craig N
CN
Scott
H Morgan
HM
Chaffin
M Keith
MK
Smith
Jacqueline L
JL
Grimm
Michael B
MB
Kuskie
Kyle R
KR
Takai
Shinji
S
Martens
Ronald J
RJ
D000193:Actinomycetales Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D000818:Animals; D006734:Horse Diseases / Q000453:epidemiology / Q000382:microbiology*; D006736:Horses; D015151:Immunoblotting / Q000662:veterinary; D015994:Incidence; D007629:Kentucky / Q000453:epidemiology; D018410:Pneumonia, Bacterial / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D016929:Rhodococcus equi / Q000254:growth & development*; D012621:Seasons; D012988:Soil Microbiology; D011795:Surveys and Questionnaires; D037521:Virulence Factors / Q000032:analysis
D037521:Virulence Factors