Objective—To determine molecular characteristics, antimicrobial susceptibility, and toxigenicity of Clostridium difficile isolates from horses in an intensive care unit and evaluate associations among severity of clinical disease with specific strains of C difficile.
Procedures—Feces were collected from horses admitted for acute gastrointestinal tract disease with loose feces and submitted for microbial culture and immunoassay for toxin production. Polymerase chain reaction assays were performed on isolates for toxins A and B genes and strain identification.
Results—Isolates were grouped into 3 strains (A, B, and C) on the basis of molecular banding patterns. Toxins A and B gene sequences were detected in 93%, 95%, and 73% of isolates of strains A, B, and C, respectively. Results of fecal immunoassays for toxin A were positive in 40%, 63%, and 16% of horses with strains A, B, and C, respectively. Isolates in strain B were resistant to metronidazole. Horses infected with strain B were 10 times as likely to have been treated with metronidazole prior to the onset of diarrhea as horses infected with other strains. Duration from onset of diarrhea to discharge (among survivors) was longer, systemic inflammatory response syndromes were more pronounced, and mortality rate was higher in horses infected with strain B than those infected with strains A and C combined.
Conclusions and Clinical Relevance—Horses may be infected with a number of heterogeneous isolates of C difficile. Results indicated that toxigenicity and antimicrobial susceptibility of isolates vary and that metronidazole-resistant strains may be associated with severe disease.
Objective—To determine molecular characteristics of
Clostridium difficile isolates from foals with diarrhea
and identify clinical abnormalities in affected foals.
Animals—28 foals with C difficile-associated diarrhea.
Procedure—Toxigenicity, molecular fingerprinting,
and antibiotic susceptibility patterns were determined.
Information on signalment, clinical findings,
results of clinicopathologic testing, whether antimicrobials
had been administered prior to development
of diarrhea, and outcome was obtained from the
Results—Twenty-three (82%) foals survived. Toxin
A and B gene sequences were detected in isolates
from 24 of 27 foals, whereas the toxin B gene alone
was detected in the isolate from 1 foal. Results of
an ELISA for toxin A were positive for fecal samples
from only 8 of 20 (40%) foals. Ten of 23 (43%) isolates
were resistant to metronidazole. Molecular
fingerprinting revealed marked heterogeneity
among isolates, except for the metronidazole-resistant
isolates. Sixteen foals had tachypnea.
Hematologic abnormalities were indicative of
inflammation. Common serum biochemical abnormalities
included metabolic acidosis, hyponatremia,
hypocalcemia, azotemia, hypoproteinemia, hyperglycemia,
and high enzyme activities. Passive transfer
of maternal antibodies was adequate in all 12
Conclusions and Clinical Relevance—Results suggest
that a large percentage of C difficile isolates
from foals with diarrhea will have the toxin A and B
gene sequences. Because of the possibility that isolates
will be resistant to metronidazole, susceptibility
testing is warranted. Clostridium difficile isolates
from foals may have a substantial amount of molecular
heterogeneity. Clinical and hematologic findings in
affected foals are similar to those for foals with diarrhea
caused by other pathogens. (J Am Vet Med