Alterations in intestinal microbiota of elderly Irish subjects post-antibiotic therapy

J Antimicrob Chemother. 2013 Jan;68(1):214-21. doi: 10.1093/jac/dks348. Epub 2012 Sep 4.


Objectives: The human intestinal microbiota composition alters naturally with age, but is unusually perturbed by antibiotic therapy. The impact of antibiotic therapy on the composition of the intestinal microbiota of a cross-section of elderly Irish subjects (n = 185, ≥ 65 years) was investigated, taking into consideration their residence location.

Methods: Forty-two of the 185 elderly subjects were treated with at least one antibiotic within 1 month prior to faecal microbiota profiling. The residence locations of the subjects varied from long-term nursing care and rehabilitation wards to day hospitals and the community.

Results: Culture-dependent methods indicated that faecal Bifidobacterium spp. numbers were significantly reduced following antibiotic treatment (P = 0.004, 7-fold reduction), while levels of Lactobacillus spp. and Enterobacteriaceae were unaffected. The largest decrease in Bifidobacterium spp. numbers was linked to the administration of nucleic acid synthesis inhibitors (P = 0.004, 23-fold reduction). Microbiota profiling revealed a significant compositional change across nine genera following antibiotic therapy, including a relative increase in Lactobacillus spp. (P = 0.031), as well as a decrease in the number of genera identified in the antibiotic-treated subjects (n = 58), when compared with untreated subjects (n = 79). More alterations in the intestinal microbiota were observed post-nucleic acid synthesis inhibitor therapy, most notably a decrease in relative Faecalibacterium spp. numbers (P < 0.001).

Conclusions: The impact of antibiotic therapy on the intestinal microbiota in the elderly should be considered for long-term health effects, and differential susceptibility may require the development of products (e.g. prebiotics and probiotics) for at-risk subjects.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents / pharmacology*
  • Feces / microbiology*
  • Female
  • Gastrointestinal Tract / drug effects*
  • Gastrointestinal Tract / microbiology*
  • Humans
  • Ireland / epidemiology
  • Male
  • Metagenome / drug effects*
  • Metagenome / physiology
  • Time Factors


  • Anti-Bacterial Agents