A modelling framework to characterize the impact of antibiotics on the gut microbiota diversity.

Metagenomic sequencing deepened our knowledge about the role of the intestinal microbiota in human health, and several studies with various methodologies explored its dynamics during antibiotic treatments. We compared the impact of four widely used antibiotics on the gut bacterial diversity. We used plasma and fecal samples collected during and after treatment from healthy volunteers assigned to a 5-day treatment either by ceftriaxone (1 g every 24 h through IV route), ceftazidime/avibactam (2 g/500 mg every 8 h through IV route), piperacillin/tazobactam (1 g/500 mg every 8 h through IV route) or moxifloxacin (400 mg every 24 h through oral route).

Perturbation and resilience of the gut microbiome up to 3 months after β-lactams exposure in healthy volunteers suggest an important role of microbial β-lactamases.

Background: Antibiotics notoriously perturb the gut microbiota. We treated healthy volunteers either with cefotaxime or ceftriaxone for 3 days, and collected in each subject 12 faecal samples up to day 90. Using untargeted and targeted phenotypic and genotypic approaches, we studied the changes in the bacterial, phage and fungal components of the microbiota as well as the metabolome and the β-lactamase activity of the stools.

Inter-phylum circulation of a beta-lactamase-encoding gene: a rare but observable event.

Beta-lactamase-mediated degradation of beta-lactams is the most common mechanism of beta-lactam resistance in Gram-negative bacteria. Beta-lactamase-encoding genes can be transferred between closely related bacteria, but spontaneous inter-phylum transfers (between distantly related bacteria) have never been reported. Here, we describe an extended-spectrum beta-lactamase (ESBL)-encoding gene () shared between the Pseudomonadota and Bacteroidota phyla.