The researchers analyzed data from the Swedish Prescription Drug Register and the fecal metagenomes of 14,979 individuals in Sweden. They investigated the association between oral antibiotic use over 8 years and the composition of the gut microbiome. The study provided evidence of the long-term effects of antibiotics on the intestinal microflora. The research was published in Nature Medicine with doi: 10.1038/s41591-026-04284-y. They used individual-level data to assess changes in the microbiome. The main finding confirms that antibiotics affect the composition of intestinal bacteria in the long term.