Rabinowitz, K. | Search bioRxiv

bioRxiv2021

Escherichia coli strains from patients with inflammatory bowel diseases have disease-specific genomic adaptations

ObjectiveEscherichia coli is over-abundant in the gut microbiome of patients with IBD, yet most studies have focused on the adherent-invasive E. coli pathotype. Here, we aimed to identify IBD-specific or phenotype-specific genomic functions of diverse E. coli lineages. DesignWe investigated E. coli from patients with UC, CD and a pouch and healthy subjects. The majority of E. coli genomes were reconstructed directly from metagenomic samples, including publicly available and newly sequenced fecal metagenomes. Clinical metadata and biomarkers were collected. Functional analysis at the gene and mutation level and genome replication rates of E. coli strains were performed, and correlated with IBD phenotypes and biomarkers. ResultsOverall, 530 E. coli genomes were analysed. A specific E. coli lineage (B2) was more prevalent in UC compared to other IBD phenotypes. Genomic metabolic capacities varied across E. coli lineages and IBD phenotypes. Specifically, sialidases involved in host mucin utilization, were exclusively present in a single lineage and were depleted in patients with a pouch. In contrast, enzymes that hydrolyze inulin were enriched in patients with a pouch. E. coli from patients with UC were twice as likely to encode the genotoxic molecule colibactin than strains from patients with CD or pouch. Strikingly, patients with a pouch showed the highest E. coli growth rates, even in the presence of antibiotics. Fecal calprotectin did not correlate with the relative abundance of E. coli. Finally, we identified multiple IBD-specific loss-of function mutations in E. coli genes encoding for bacterial cell envelope and secretion components. ConclusionThis study presents E. coli as a commensal species better adapted to the overly-active mucosal immune milieu in IBD, that may benefit from intestinal inflammation, rather than causing it. The evidence given here suggests adaptive evolution toward attenuated virulence in some E. coli strains, coupled with a rapid growth despite the presence of antibiotics.

genomics↗

bioRxiv2018

Prolonged Antibiotic Treatment Generates a Fluoroquinolone Resistant Gut Microbiome and Collateral Multi-Drug Resistance

One Sentence SummaryThe majority of the gut microbiome develops antibiotic resistance via point-mutations in addition to collateral resistance whereas its density is only moderately decreased following long-term antibiotic treatment.\n\nABSTRACTAntibiotic resistance in bacterial pathogens represents a growing threat to modern medicine. Limitation of lengthy and broad-spectrum antibacterial treatment regimens is generally recommended. Nevertheless, some conditions may require prolonged antibiotic treatment. The effects of such treatments on bacterial communities, specifically their resistome, is yet unknown. Here, we followed a unique cohort of patients with ulcerative colitis who underwent total large bowel resection and the formation of an ileal pouch from their normal small bowel. The majority of these patients tend to develop inflammation of this previously normal small bowel, known as \"pouchitis\". Pouchitis is commonly treated with repeated or prolonged courses of broad-spectrum antibiotics. By using metagenomics of faecal samples obtained longitudinally from patients treated with antibiotics for prolonged periods, we hereby show that the majority of their gut commensal bacteria develop antibiotic resistance by point-mutations. In addition, some bacterial species had acquired multidrug resistance loci with genes that confer resistance to the drug used in the treatment (ciprofloxacin) but co-localized with genes encoding extended-spectrum {beta}-lactamases and other resistance-conferring enzymes. We further show that bacterial density in faecal samples is only modestly reduced despite the long-term antibiotic treatment, thereby questioning the current rationale that antibiotic efficacy in treating pouch inflammation is due to the reduction of bacterial load. This study reveals the impact and dynamics of prolonged antibiotic treatment on human gut microbiomes and provides insights that may guide the development of future IBD therapies. It also provides novel insights into bacterial community recovery after cessation of such prolonged treatment, and highlights the increased risk of spreading mobile antibiotic resistance.

microbiology↗