Short-Term Effect of Antibiotics on Human Gut Microbiota

Abstract

From birth onwards, the human gut microbiota rapidly increases in diversity and reaches an adult-like stage at three years of age. After this age, the composition may fluctuate in response to external factors such as antibiotics. Previous studies have shown that resilience is not complete months after cessation of the antibiotic intake. However, little is known about the short-term effects of antibiotic intake on the gut microbial community. Here we examined the load and composition of the fecal microbiota immediately after treatment in 21 patients, who received broad-spectrum antibiotics such as fluoroquinolones and β-lactams. A fecal sample was collected from all participants before treatment and one week after for microbial load and community composition analyses by quantitative PCR and pyrosequencing of the 16S rRNA gene, respectively. Fluoroquinolones and β-lactams significantly decreased microbial diversity by 25% and reduced the core phylogenetic microbiota from 29 to 12 taxa. However, at the phylum level, these antibiotics increased the Bacteroidetes/Firmicutes ratio (p = 0.0007, FDR = 0.002). At the species level, our findings unexpectedly revealed that both antibiotic types increased the proportion of several unknown taxa belonging to the Bacteroides genus, a Gram-negative group of bacteria (p = 0.0003, FDR<0.016). Furthermore, the average microbial load was affected by the treatment. Indeed, the β-lactams increased it significantly by two-fold (p = 0.04). The maintenance of or possible increase detected in microbial load and the selection of Gram-negative over Gram-positive bacteria breaks the idea generally held about the effect of broad-spectrum antibiotics on gut microbiota.

Discordant temporal development of bacterial phyla and the emergence of core in the fecal microbiota of young children

“…The result is in line with previous studies showing that antibiotics reduce microbiota stability and diversity (Rehman et al, 2012;Panda et al, 2014). We found that the abundance of Clostridium cluster XIVa was significantly decreased in the next sample after antibiotic course.…”

Rhein 8-<i>O</i>-β-D-Glucopyranoside Elicited the Purgative Action of Daiokanzoto (Da-Huang-Gan-Cao-Tang), Despite Dysbiosis by Ampicillin

“…Bacteroides develops natural resistance to antibiotics, and particularly to penicillin antibiotics, by producing β-lactamase, and several reports have shown that the ratios of Bacteroides are increased in the presence of β-lactams, such as ampicillin. [25][26][27] Our present finding that Bacteroides were increased by continuous ampicillin treatment tended to be similar to these previous reports. From the results on purgative action, which continued throughout the eight days of ampicillin treatment, the purgative action of SA was inhibited, but that of DKT was increased, which proved that RG was involved in these effects.…”

Helsinki alert of biodiversity and health

“…Recent evidence from humans indicates that the use of the most common antibiotics, β-lactams and macrolides, not only disturbs the composition of the gut microbiota (by decreasing its diversity and reducing the number of core taxa (97), but can also affect many metabolic functions, including sugar metabolism and synthesis and degradation of intestinal/colonic epithelium components (98). Resilience of the gut microbiota often takes months after the cessation of the antibiotic use, although there are great variations between different antibiotics; their effect on the gut microbiota is dependent on the properties of the antimicrobial agent, and the structure, function and resistance genes of the microbial community (99).…”