title: The Human Gut Microbiome as a Transporter of Antibiotic Resistance Genes between Continents.
abstract: Previous studies of antibiotic resistance dissemination by travel have, by targeting only a select number of cultivable bacterial species, omitted most of the human microbiome. Here, we used explorative shotgun metagenomic sequencing to address the abundance of >300 antibiotic resistance genes in fecal specimens from 35 Swedish students taken before and after exchange programs on the Indian peninsula or in Central Africa. All specimens were additionally cultured for extended-spectrum beta-lactamase (ESBL)-producing enterobacteria, and the isolates obtained were genome sequenced. The overall taxonomic diversity and composition of the gut microbiome remained stable before and after travel, but there was an increasing abundance of Proteobacteria in 25/35 students. The relative abundance of antibiotic resistance genes increased, most prominently for genes encoding resistance to sulfonamide (2.6-fold increase), trimethoprim (7.7-fold), and beta-lactams (2.6-fold). Importantly, the increase observed occurred without any antibiotic intake. Of 18 students visiting the Indian peninsula, 12 acquired ESBL-producing Escherichia coli, while none returning from Africa were positive. Despite deep sequencing efforts, the sensitivity of metagenomics was not sufficient to detect acquisition of the low-abundant genes responsible for the observed ESBL phenotype. In conclusion, metagenomic sequencing of the intestinal microbiome of Swedish students returning from exchange programs in Central Africa or the Indian peninsula showed increased abundance of genes encoding resistance to widely used antibiotics.
authors.affiliation: Department of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Bengtsson-Palme
authors.affiliation: Department of Clinical Microbiology, Infectious Diseases, Umeå University, Umeå, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Angelin
authors.affiliation: Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Huss
authors.affiliation: Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden.
authors.forename: Sanela
authors.initials: S
authors.lastname: Kjellqvist
authors.affiliation: Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden.
authors.forename: Erik
authors.initials: E
authors.lastname: Kristiansson
authors.affiliation: Department of Clinical Microbiology, Infectious Diseases, Umeå University, Umeå, Sweden.
authors.forename: Helena
authors.initials: H
authors.lastname: Palmgren
authors.affiliation: Department of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: D G Joakim
authors.initials: DG
authors.lastname: Larsson
authors.affiliation: Laboratory for Molecular Infection Medicine Sweden, Department of Clinical Microbiology, Bacteriology, Umeå University, Umeå, Sweden anders.f.johansson@umu.se.
authors.forename: Anders
authors.identifier: http://orcid.org/0000-0003-0548-5943
authors.initials: A
authors.lastname: Johansson
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004352:Drug Resistance, Microbial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects; D005243:Feces / Q000382:microbiology; D005260:Female; D000069196:Gastrointestinal Microbiome / Q000235:genetics*; D006801:Humans; D008297:Male; D056186:Metagenomics; D008826:Microbial Sensitivity Tests; D020560:Proteobacteria / Q000187:drug effects / Q000235:genetics; D013449:Sulfonamides / Q000494:pharmacology; D014295:Trimethoprim / Q000494:pharmacology; D055815:Young Adult; D047090:beta-Lactams / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D013449:Sulfonamides; D047090:beta-Lactams; D014295:Trimethoprim