Summary: A significant increase was found over time in enterococci (day 14 versus
day 0) and significant decreases were found in lactobacilli
(day 7 versus 0) and spore-forming clostridia with amoxicillin.
Amoxicillin treatment resulted in reduced species richness and diversity, and a significant shift in the relative abundance of 35 taxa at different ranks from phylum to species-level phylotype. At the phylum level, prevalence of TM7 and Actinobacteria decreased at the end of treatment, whereas Proteobacteria had a higher relative abundance post-treatment. The results point to a substantial but incomplete recovery of the salivary bacterial community from the antibiotic about 3 weeks after the end of treatment.
This study showed that a 7 day amoxicillin treatment did not alter the counts of Bifidobacterium. However amoxicillin can have an impact by changing the microbiota at the species level and decreased the diversity of this population.
The use of amoxicillin also influenced the intestinal microbiota, significantly decreasing the CFU of Bifidobacterium spp. and Lactobacillus spp./g of feces. Changes in the composition of the intestinal microbiota need to be observed, since a decrease in the normal microorganisms can pose a number of hazards for hosts, including decreased resistance to colonization.