Changes in fecal microbiota of healthy dogs administered amoxicillin

Anne Mette R. Grønvold, Trine M. L'Abée-Lund, Henning Sørum, Ellen Skancke, Anthony C. Yannarell, Roderick I. MacKie

Research output: Contribution to journalArticlepeer-review


The effect of oral amoxicillin treatment on fecal microbiota of seven healthy adult dogs was determined with a focus on the prevalence of bacterial antibiotic resistance and changes in predominant bacterial populations. After 4-7 days of exposure to amoxicillin, fecal Escherichia coli expressed resistance to multiple antibiotics when compared with the pre-exposure situation. Two weeks postexposure, the susceptibility pattern had returned to pre-exposure levels in most dogs. A shift in bacterial populations was confirmed by molecular fingerprinting of fecal bacterial populations using denaturing gradient gel electrophoresis (PCR-DGGE) of the 16S V3 rRNA gene region. Much of the variation in DGGE profiles could be attributed to dog-specific factors. However, permutation tests indicated that amoxicillin exposure significantly affected the DGGE profiles after controlling for the dog effect (P=0.02), and pre-exposure samples were clearly separated from postexposure samples. Sequence analysis of DGGE bands and real-time PCR quantification indicated that amoxicillin exposure caused a shift in the intestinal ecological balance toward a Gram-negative microbiota including resistant species in the family Enterobacteriaceae.

Original languageEnglish (US)
Pages (from-to)313-326
Number of pages14
JournalFEMS microbiology ecology
Issue number2
StatePublished - Feb 2010


  • Antibiotic resistance
  • Dog
  • Fecal microbiota
  • Microbial ecology
  • Real-time PCR

ASJC Scopus subject areas

  • Microbiology
  • Ecology
  • Applied Microbiology and Biotechnology


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