Journal of the American Veterinary Medical Association2003; 220(1); 67-73; doi: 10.2460/javma.2002.220.67

Characterization of Clostridium difficile isolates from foals with diarrhea: 28 cases (1993-1997).

Abstract: To determine molecular characteristics of Clostridium difficile isolates from foals with diarrhea and identify clinical abnormalities in affected foals. Methods: Retrospective study. Methods: 28 foals with C difficile-associated diarrhea. Methods: 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 medical records. 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 foals evaluated. Conclusions: 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.
Publication Date: 2003-04-12 PubMed ID: 12680451DOI: 10.2460/javma.2002.220.67Google Scholar: Lookup
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  • Journal Article
  • Research Support
  • Non-U.S. Gov't


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This research studied the characteristics of Clostridium difficile bacteria from foals with diarrhea and identified clinical abnormalities in affected foals, finding a high survival rate and a large percentage of bacteria with toxin A and B gene sequences.

Research Methods

  • A retrospective study was conducted on 28 foals with C Difficile-associated diarrhea.
  • Characteristics such as toxigenicity, molecular fingerprinting, and antibiotic susceptibility were determined by reviewing the foals’ medical records for pieces of information including clinical findings and results of clinicopathologic testing.
  • The researchers also noted whether the foals had previously received antimicrobials prior to the development of diarrhea and what the outcome for each foal was.


  • Out of the 28 foals, 23 survived (82%).
  • Gene sequences for toxin A and B were found in the bacteria isolated from 24 out of 27 foals. In one case, only the gene sequence for toxin B was found.
  • An ELISA test used to detect for toxin A revealed a positive result in only 40% of the samples.
  • Out of the 23 isolates tested, 43% were resistant to the antibiotic metronidazole, a medication often used to treat bacteria-related infections.
  • Molecular fingerprinting was used to examine the genetic variation among the different bacteria samples. There was a significant amount of heterogeneity among the different isolates, except for those that were resistant to metronidazole.

Clinical Symptoms

  • Several clinical symptoms and hematologic abnormalities indicative of inflammation were observed in the affected foals.
  • Hemoglobin levels were abnormal in 16 foals and showed signs of tachypnea, a condition characterized by rapid breathing.
  • Other common serum biochemical abnormalities included metabolic acidosis, hyponatremia, hypocalcemia, azotemia, hypoproteinemia, hyperglycemia, and high enzyme activities.
  • Adequate passive transfer of maternal antibodies was observed in all 12 foals evaluated, which is key in providing initial immunity to the foals.


  • This research found that a large percentage of C Difficile bacteria isolated from foals with diarrhea contain the toxin A and B gene sequences.
  • It also indicated a potential resistance to metronidazole, suggesting a need for susceptibility testing before administrating the antibiotic.
  • Furthermore, the extensive molecular heterogeneity among the isolates was also observed, emphasizing the need for a more personalized approach to treatment.
  • Lastly, clinical and hematological findings in C Difficile infected foals were similar to those infected by other diarrheal pathogens, suggesting similar impacts on the health of the affected foals.

Cite This Article

Magdesian KG, Hirsh DC, Jang SS, Hansen LM, Madigan JE. (2003). Characterization of Clostridium difficile isolates from foals with diarrhea: 28 cases (1993-1997). J Am Vet Med Assoc, 220(1), 67-73.


ISSN: 0003-1488
NlmUniqueID: 7503067
Country: United States
Language: English
Volume: 220
Issue: 1
Pages: 67-73

Researcher Affiliations

Magdesian, K Gary
  • Department of Medicine and Epidemiology, Veterinary Medical Teaching Hospital, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
Hirsh, Dwight C
    Jang, Spencer S
      Hansen, Lori M
        Madigan, John E

          MeSH Terms

          • Animals
          • Anti-Bacterial Agents / therapeutic use
          • Bacterial Proteins
          • Bacterial Toxins / analysis
          • Bacterial Toxins / biosynthesis
          • Bacterial Toxins / genetics
          • Clostridioides difficile / classification
          • Clostridioides difficile / drug effects
          • Clostridioides difficile / physiology
          • Clostridium Infections / microbiology
          • Clostridium Infections / veterinary
          • Diarrhea / microbiology
          • Diarrhea / veterinary
          • Drug Resistance, Bacterial
          • Enterotoxins / analysis
          • Enterotoxins / genetics
          • Enzyme-Linked Immunosorbent Assay / veterinary
          • Feces / chemistry
          • Female
          • Horse Diseases / microbiology
          • Horses
          • Male
          • Metronidazole / therapeutic use
          • Microbial Sensitivity Tests / veterinary
          • Polymerase Chain Reaction / veterinary
          • Retrospective Studies


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