title: The Ellis Island Effect: A novel mobile element in a multi-drug resistantBacteroides fragilisclinical isolate includes a mosaic of resistance genes from Gram-positive bacteria.
abstract: Objectives:Bacteroides fragilis, a Gram-negative anaerobic bacterium, is alternately a gut commensal or virulent pathogen and is an important reservoir for horizontal gene transfer (HGT) of bacterial resistance and virulence genes in the human gastrointestinal tract. We identified a unique conjugative transposon (CTn) in a multidrug resistant clinical isolate ofB. fragilis(BF-HMW615); we named this element CTnHyb because it included a hybrid mosaic of foreign elements. This study reports the characterization of CTnHyb and discusses the potential impact on horizontal spread of resistance genes.Results:CTnHyb contains several efflux pump genes and several genes that confer or may confer antibiotic resistance to tetracycline, kanamycin, metronidazole and spectinomycin (truncated gene). CTnHyb also contains a mosaic of mobile elements from Gram-positive organisms. CTnHyb is easily transferred from BF-HMW615 (the original isolate) to BF638R (lab strain) and integrated into the BF638R chromosome. The "foreign" (from Gram-positive bacteria) nucleotide sequences within CTnHyb were > 99% preserved indicating that the gene acquisition from the Gram-positive bacteria was very recent.Conclusion:CTnHyb is a novel CTn residing in a multidrug resistant strain ofB. fragilis. The global nature and wide phylogenetic reach of HGT means that any gene in any bacterium can potentially be mobilized. Understanding the mechanisms that drive the formation and transfer of these elements and, potentially, ways to limit the transfer are necessary to prevent a devastating spread of resistance elements.
authors.affiliation: GLAVAHCS; Los Angeles, CA USA.
authors.forename: Fasahath
authors.initials: F
authors.lastname: Husain
authors.affiliation: GLAVAHCS; Los Angeles, CA USA ; David Geffen School of Medicine; University of California Los Angeles; Los Angeles, CA USA.
authors.forename: Yaligara
authors.initials: Y
authors.lastname: Veeranagouda
authors.affiliation: GLAVAHCS; Los Angeles, CA USA.
authors.forename: Renata
authors.initials: R
authors.lastname: Boente
authors.affiliation: David Geffen School of Medicine; University of California Los Angeles; Los Angeles, CA USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Tang
authors.affiliation: David Geffen School of Medicine; University of California Los Angeles; Los Angeles, CA USA.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Mulato
authors.affiliation: GLAVAHCS; Los Angeles, CA USA ; David Geffen School of Medicine; University of California Los Angeles; Los Angeles, CA USA.
authors.forename: Hannah M
authors.initials: HM
authors.lastname: Wexler
keywords: antimicrobial resistance; bacteroides; conjugative transposon; horizontal gene transfer; integrative conjugal element