Equis ISSN 2398-2977

Feces: bacteriology

Contributor(s): Annalisa Barrelet, Simon Peek


  • Diagnosis of bacterial infections causing enteritis/colitis   Colitis X  .
  • Provision of antibiotic sensitivity profile for significant isolates.
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  • Owing to the large number of normal flora in the intestinal tract, selective media should be used to retard the growth of normal flora and selectively enrich the growth of Salmonellaspp   Salmonella spp  .
  • Selenite broth should be inoculated, and subcultured onto DCA or MacConkey agar after 12-24 h, or tetrathionate broth inoculated and isolates subcultured onto brilliant green agar.
  • Direct cultures onto MacConkey and/or blood agar may be used in case Salmonellais present in sufficient numbers to grow directly.
  • Suspect colonies are tested for H2S production, urease activity, etc. Serotyping is performed at specialist DEFRA labs in the UK. A PCR applicable to feces has recently been described.
  • Investigation of enteric clostridiosis is based on anaerobic culture and speciation as well as genotyping within a species ( Clostridium perfringens  Clostridium perfringens  ).
  • Some laboratories offer specific toxin identification for Clostridium difficile  Clostridium difficile  (cytotoxin) and Clostridium perfringens  Clostridium perfringens   (enterotoxin).


  • Standard.



  •  Salmonellamay be present in low numbers, and several (at least 3) fecal samples should be collected at at least 12 h intervals to increase the probability of diagnosis.
  • Positive Salmonellaculture may be more likely as fecal consistency improves from peracute stage.
  • Alternatively, a rectal biopsy specimen may be ground up and cultured. Up to 20% of horses are thought to be silent (non-shedding) carriers.

Result Data

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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Willing B et al (2009) Changes in faecal bacteria associated with concentrate and forage-only diets fed to horses in training. Equine Vet J 41 (9), 908-914.