Evaluation of fecal samples from mares as a source of Rhodococcus equi for their foals by use of quantitative bacteriologic culture and colony immunoblot analyses.
OBJECTIVE
To determine whether mares are a clinically important source of Rhodococcus equi for their foals.


METHODS
171 mares and 171 foals from a farm in Kentucky (evaluated during 2004 and 2005).


METHODS
At 4 time points (2 before and 2 after parturition), the total concentration of R equi and concentration of virulent R equi were determined in fecal specimens from mares by use of quantitative bacteriologic culture and a colony immunoblot technique, respectively. These concentrations for mares of foals that developed R equi-associated pneumonia and for mares with unaffected foals were compared. Data for each year were analyzed separately.


RESULTS
R equi-associated pneumonia developed in 53 of 171 (31%) foals. Fecal shedding of virulent R equi was detected in at least 1 time point for every mare; bacteriologic culture results were positive for 62 of 171 (36%) mares at all time points. However, compared with dams of unaffected foals, fecal concentrations of total or virulent R equi in dams of foals with R equi-associated pneumonia were not significantly different.


CONCLUSIONS
Results indicate that dams of foals with R equi-associated pneumonia did not shed more R equi in feces than dams of unaffected foals; therefore, R equi infection in foals was not associated with comparatively greater fecal shedding by their dams. However, detection of virulent R equi in the feces of all mares during at least 1 time point suggests that mares can be an important source of R equi for the surrounding environment.
Grimm
Michael B
MB
Equine Infectious Disease Laboratory, Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA.
Cohen
Noah D
ND
Slovis
Nathan M
NM
Mundy
George D
GD
Harrington
Jessica R
JR
Libal
Melissa C
MC
Takai
Shinji
S
Martens
Ronald J
RJ
D000193:Actinomycetales Infections / Q000382:microbiology / Q000635:transmission / Q000662:veterinary*; D000818:Animals; D000831:Animals, Newborn; D015169:Colony Count, Microbial / Q000662:veterinary; D005243:Feces / Q000382:microbiology; D005260:Female; D006734:Horse Diseases / Q000382:microbiology* / Q000635:transmission; D006736:Horses; D015151:Immunoblotting / Q000662:veterinary; D018445:Infectious Disease Transmission, Vertical; D018410:Pneumonia, Bacterial / Q000382:microbiology / Q000662:veterinary*; D011247:Pregnancy; D016929:Rhodococcus equi / Q000254:growth & development* / Q000472:pathogenicity; D018709:Statistics, Nonparametric; D014774:Virulence