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Investigation of factors influencing the successful persistence and dissemination of a globally distributed antibiotic resistance plasmids

Cottell, Jennifer L (2012)
Ph.D. thesis, University of Birmingham.

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The aim of this study was to determine the extent of dissemination of pCT, a blaCTX-M-14 carrying plasmid, and to investigate the factors which allow pCT to stably persist within bacterial populations.

DNA sequencing of pCT allowed the design of a PCR assay for rapid detection of pCT, which showed pCT has disseminated worldwide in bacteria from humans, animals and the environment. pCT was stably maintained in the absence of β-lactam antibiotic pressure in four different bacterial host strains over ~70 generations, and conferred neither a fitness advantage nor disadvantage to two host E. coli strains. Seven pCT genes of interest in relation to plasmid success were identified and insertionally inactivated to investigate their role in the ‘success’ of this plasmid. Inactivation the conjugation pilus reduced the frequency of pCT transfer however inactivation of the five other pCT genes had no consistent effect on the host bacterial strain persistence or dissemination.

In conclusion, pCT was shown to be a globally successful plasmid. The persistence and spread of pCT is postulated to be due to a combination of stability, a lack of a fitness burden and proficient conjugation, rather than any one particular gene or phenotypic benefit conferred to the host.

Type of Work:Ph.D. thesis.
Supervisor(s):Piddock, Laura
School/Faculty:Colleges (2008 onwards) > College of Medical & Dental Sciences
Department:School of Immunity and Infection
Subjects:RA Public aspects of medicine
Institution:University of Birmingham
ID Code:3312
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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