title: Antibiotic resistance is prevalent in an isolated cave microbiome.
abstract: Antibiotic resistance is a global challenge that impacts all pharmaceutically used antibiotics. The origin of the genes associated with this resistance is of significant importance to our understanding of the evolution and dissemination of antibiotic resistance in pathogens. A growing body of evidence implicates environmental organisms as reservoirs of these resistance genes; however, the role of anthropogenic use of antibiotics in the emergence of these genes is controversial. We report a screen of a sample of the culturable microbiome of Lechuguilla Cave, New Mexico, in a region of the cave that has been isolated for over 4 million years. We report that, like surface microbes, these bacteria were highly resistant to antibiotics; some strains were resistant to 14 different commercially available antibiotics. Resistance was detected to a wide range of structurally different antibiotics including daptomycin, an antibiotic of last resort in the treatment of drug resistant Gram-positive pathogens. Enzyme-mediated mechanisms of resistance were also discovered for natural and semi-synthetic macrolide antibiotics via glycosylation and through a kinase-mediated phosphorylation mechanism. Sequencing of the genome of one of the resistant bacteria identified a macrolide kinase encoding gene and characterization of its product revealed it to be related to a known family of kinases circulating in modern drug resistant pathogens. The implications of this study are significant to our understanding of the prevalence of resistance, even in microbiomes isolated from human use of antibiotics. This supports a growing understanding that antibiotic resistance is natural, ancient, and hard wired in the microbial pangenome.
authors.affiliation: MG DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Kirandeep
authors.initials: K
authors.lastname: Bhullar
authors.forename: Nicholas
authors.initials: N
authors.lastname: Waglechner
authors.forename: Andrew
authors.initials: A
authors.lastname: Pawlowski
authors.forename: Kalinka
authors.initials: K
authors.lastname: Koteva
authors.forename: Eric D
authors.initials: ED
authors.lastname: Banks
authors.forename: Michael D
authors.initials: MD
authors.lastname: Johnston
authors.forename: Hazel A
authors.initials: HA
authors.lastname: Barton
authors.forename: Gerard D
authors.initials: GD
authors.lastname: Wright
mesh_terms: D000900:Anti-Bacterial Agents / Q000276:immunology; D001419:Bacteria / Q000235:genetics*; D005075:Biological Evolution; D004352:Drug Resistance, Microbial / Q000235:genetics* / Q000276:immunology; D016680:Genome, Bacterial; D006801:Humans; D054892:Metagenome / Q000235:genetics* / Q000276:immunology; D009516:New Mexico; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D017853:Phosphotransferases (Alcohol Group Acceptor); C061369:macrolide 2'-kinase