Examination of the horizontal gene transfer dynamics of an integrative conjugative element encoding multi-drug resistance in Histophilus somni

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dc.contributor.advisorLiljebjelke, Karen
dc.contributor.authorFarghaly, Mai Mohammed
dc.contributor.committeememberHynes, Michael
dc.contributor.committeemembervan der Meer, Frank
dc.dateSpring Convocation
dc.date.accessioned2021-08-04T22:24:36Z
dc.date.embargolift2021-07-15
dc.date.issued2021-01-15
dc.description.abstractIntegrative and conjugative elements (ICEs) are autonomous-transferred mobile genetic elements that play a significant role in disseminating antimicrobials between bacteria via horizontal gene transfer (HGT). One recently identified ICE in a clinical isolate of H. somni named ICEHs02 is 72,914 base pairs in length and harbours seven AMR genes which confer resistance to tetracycline (tetR-tet(H)), florfenicol (floR), sulfonamide (sul2), aminoglycoside (APH(3'')-Ib), (APH(6)-Id), and (APH(3')-Ia), and copper (mco). This study investigated the host range of ICEHs02, assessed the effect of antimicrobial stressors on transfer frequency of ICEHs02, and examined effects of ICE acquisition on the host. In vitro conjugation assays were conducted to examine the frequency of transfer of ICEHs02 into other bacteria. PCR and sequence analysis confirmed the presence of ICEHs02 and its circular intermediate in recipient strains. The susceptibility of ICEHs02-carrying recipients was conducted using broth microdilution. The effect of tetracycline and ciprofloxacin on transfer frequency and excision rates was investigated using mating assays and qPCR. Growth curves and competition experiments were conducted to assess the fitness cost of ICEHs02 on the host. ICEHs02 was observed to transfer into H. somni and Pasteurella multocida. PCR assays confirmed the presence of the circular intermediate, ICE-associated core genes and accessory genes in recipient strains. Susceptibility testing confirmed the function of ICEHs02-associated AMR genes in recipient strains. Tetracycline and ciprofloxacin induction significantly increased the transfer rates of ICEHs02. The copy numbers of the circular intermediate of ICEHs02 per chromosome exhibited significant increases of ~ 37-fold after tetracycline exposure, and ~ 4-fold after ciprofloxacin treatment. The acquisition of ICEHs02 reduced the relative fitness of H. somni TG by 28% (w = 0.72 ± 0.04) and P. multocida TG relative fitness was decreased by 15% (w = 0.85 ± 0.01). In conclusion, this study provided information on the host range of the multi-drug resistant ICEHs02, gave insight into the regulatory role of antibiotics on the HGT of ICEs and emphasized the importance of ICEs in the dissemination of AMR between bacteria.
dc.identifier.citationFarghaly, M. M. (2020). Examination of the horizontal gene transfer dynamics of an integrative conjugative element encoding multi-drug resistance in Histophilus somni (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/39069
dc.identifier.urihttp://hdl.handle.net/1880/113703
dc.language.isoenen
dc.language.isoEnglish
dc.publisher.facultyGraduate Studiesen
dc.publisher.facultyVeterinary Medicine
dc.publisher.institutionUniversity of Calgaryen
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.en
dc.subjectHistophilus somni, horizontal gene transfer, integrative and conjugative elements, antimicrobial resistance, metal tolerance.
dc.subject.classificationBiological Sciences
dc.subject.classificationHealth And Environmental Sciences
dc.titleExamination of the horizontal gene transfer dynamics of an integrative conjugative element encoding multi-drug resistance in Histophilus somni
dc.typemaster thesis
thesis.degree.disciplineVeterinary Medical Sciences
thesis.degree.grantorUniversity of Calgaryen
thesis.degree.grantorUniversity of Calgary
thesis.degree.nameMaster of Science (MSc)
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