title: Clostridium difficile: prevalence in horses and environment, and antimicrobial susceptibility.
abstract: BACKGROUND
  Clostridium difficile has been associated with acute colitis in mature horses.
  
  
  OBJECTIVE
  To survey C. difficile colonisation of the alimentary tract with age, occurrence of diarrhoea and history of antibiotic therapy; and to study the occurrence and survival of C. difficile in the environment and antimicrobial susceptibility of isolated strains.
  
  
  METHODS
  A total of 777 horses of different breeds, age and sex were studied. Further, 598 soil samples and 434 indoor surface samples were examined. Antimicrobial susceptibility of 52 strains was investigated by Etest for 10 antibiotics.
  
  
  RESULTS
  In horses that developed acute colitis during antibiotic treatment, 18 of 43 (42%) were positive to C. difficile culture and 12 of these (28%) were positive in the cytotoxin B test. Furthermore, C. difficile was isolated from a small number of diarrhoeic mature horses (4 of 72 [6%]) with no history of antibiotic treatment, but not from 273 healthy mature horses examined or 65 horses with colic. An interesting new finding was that, in normal healthy foals age < 14 days, C. difficile was isolated from 1/3 of foals (16 of 56 [29%]). All older foals (170) except one were negative. Seven of 16 (44%) nondiarrhoeic foals treated with erythromycin or gentamicin in combination with rifampicin were also excretors of C. difficile. On studfarms, 14 of 132 (11%) outdoor soil samples were positive for C. difficile in culture, whereas only 2 of 220 (1%) soil samples from farms with mature horses were positive for C. difficile (P = < 0.001). By PCR, it was demonstrated that strains from the environment and healthy foals can serve as a potential reservoir of toxigenic C. difficile. The experimental study conducted here found that C. difficile survived in nature and indoors for at least 4 years in inoculated equine faeces. The susceptibility of 52 strains was investigated for 10 antibiotics and all were susceptible to metronidazole (MIC < or = 4 mg/l) and vancomycin (MIC < or = 2 mg/l).
  
  
  CONCLUSIONS
  C. difficile is associated with acute colitis in mature horses, following antibiotic treatment. Furthermore, C. difficile was isolated from 1 in 3 normal healthy foals age < 14 days.
  
  
  CONCLUSIONS
  Strains from healthy foals and the environment can serve as a potential reservoir of toxigenic C. difficile.
authors.affiliation: Department of Bacteriology, National Veterinary Institute, SE-751 89 Uppsala, Sweden.
authors.forename: V
authors.initials: V
authors.lastname: Båverud
authors.forename: A
authors.initials: A
authors.lastname: Gustafsson
authors.forename: A
authors.initials: A
authors.lastname: Franklin
authors.forename: A
authors.initials: A
authors.lastname: Aspán
authors.forename: A
authors.initials: A
authors.lastname: Gunnarsson
mesh_terms: D000208:Acute Disease; D000367:Age Factors; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000032:analysis; D016360:Clostridioides difficile / Q000187:drug effects* / Q000254:growth & development / Q000302:isolation & purification; D003092:Colitis / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D015169:Colony Count, Microbial; D003967:Diarrhea / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D004197:Disease Reservoirs / Q000662:veterinary; D024881:Drug Resistance, Bacterial; D004761:Enterocolitis, Pseudomembranous / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D005243:Feces / Q000737:chemistry / Q000382:microbiology; D005260:Female; D006734:Horse Diseases / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D006736:Horses; D008297:Male; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D015995:Prevalence; D012988:Soil Microbiology
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D001427:Bacterial Toxins; C031815:toxB protein, Clostridium difficile