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Dental unit water lines as reservoirs for antimicrobial resistance gene dissemination

PGR-P-2269

Key facts

Type of research degree
PhD
Application deadline
Thursday 26 June 2025
Project start date
Monday 1 September 2025
Country eligibility
UK only
Funding
Funded
Source of funding
University of Leeds
Supervisors
Professor Thuy Do and Dr Paula Lancaster
Additional supervisors
Dr Jon Vernon
Schools
School of Dentistry
<h2 class="heading hide-accessible">Summary</h2>

The award is open to full-time or part-time candidates (UK only) who meet the eligibility for a place on a PhD degree at the School of Dentistry. This project would suit a student with a background in physical science with interest in biological systems, or in biological science with an interest in physical techniques.<br /> <br /> International applicants may apply but must make up the difference between UK International tuition fees. Candidates whose first language is not English must provide evidence that their English language is sufficient to meet the specific demands of their study.<br />

<h2 class="heading hide-accessible">Full description</h2>

<p>Dental equipment often relies on water feeds for cooling and irrigation during oral procedures. The narrow bore tubing used has a high surface area and holds stagnant water during non-operational periods, creating an ideal environment for microorganisms. These bacterial populations harbour antimicrobial resistance (AMR) genes, which pose significant healthcare challenges. Microbial contamination of dental unit waterlines (DUWL) is widely reported, (1, 2) making it a significant infection control issue. Even non-pathogenic organisms can harbour AMR genes, with the potential to transfer these elements to harmful organisms. High-speed dental instruments produce aerosols, which can disseminate microorganisms into the air, posing a threat to clinicians and patients. (3) The AMR genes carried by these bacteria can then be transferred within the diverse oral community and potentially to the gut. (4) <br /> Evidence shows that bacterial contamination of DUWLs occur, and that AMR elements can transfer between bacteria. However, little is known regarding AMR gene dissemination via dental aerosols. This study will explore the relationship between the DUWL resistome and its potential transfer to patients and clinicians.  <br />  </p> <h2><br /> <strong>Experimental Approach </strong></h2> <p><br /> DUWL samples will be collected from patient facing clinics and dental simulation labs to represent different levels of proximity, disinfection, and potential exposure. Aerosol modelling will be used in dummy simulations of clinical procedures, with strategically positioned filter papers and biological air samplers to collect aerosolized microorganisms. (3) DNA will be extracted and analysed using in-house bioinformatics pipelines and publicly available databases to identify AMR genes. Comparisons of pre- and post-decontamination will outline its efficacy.</p> <p> </p> <h2><strong>Aims & Objectives </strong></h2> <p><br /> In the wake of the COVID-19 pandemic, the impact of dental aerosols is more apparent. Their potential involvement in AMR gene dissemination is crucial to understand. Therefore, in alignment with WHO priorities in tackling AMR, it is now appropriate to investigate undiscovered reservoirs burdening our healthcare systems. <br />  <br /> •Characterize AMR genes in DUWLs at a large dental school setting. <br /> •Assess the risk of AMR gene transfer from DUWLs to patient mouths via dental tools. <br /> •Quantify aerosolized AMR genes during various dental procedures. <br /> •Investigate the impact of decontamination processes on AMR genes. </p> <p> </p> <h2><strong>References:</strong></h2> <p><br /> 1.    Wirthlin MR, Marshall Jr GW, Rowland RW. Formation and decontamination of biofilms in dental unit waterlines. Journal of periodontology. 2003;74(11):1595-609. <br /> 2.    Szymanska J, Sitkowska J, Dutkiewicz J. Microbial contamination of dental unit waterlines. Annals of Agricultural and Environmental Medicine. 2008;15(2). <br /> 3.    Vernon JJ, Black EVI, Dennis T, Devine DA, Fletcher L, Wood DJ, Nattress BR. Dental Mitigation Strategies to Reduce Aerosolization of SARS-CoV-2. Journal of Dental Research. 2021:00220345211032885. <br /> 4.    Lerminiaux NA, Cameron ADS. Horizontal transfer of antibiotic resistance genes in clinical environments. Canadian Journal of Microbiology. 2019;65(1):34-44. </p> <p> </p> <h3><strong>Information about the Award:</strong></h3> <p>o    We are offering 1 full-time PhD scholarship in the School of Dentistry for one UK candidate, covering a maintenance grant of £20,780 per year and UK tuition fees for three years, subject to satisfactory progress. </p> <h3><br /> <strong>Duration of the Award</strong></h3> <p><br /> o    Full-time (3 years). The award will be made for one year in the first instance and renewable for a further period of up to two years, subject to satisfactory academic progress.</p> <h3><br /> <strong>Other Conditions</strong></h3> <p><br /> o    Applicants must not have already been awarded or be currently studying for a doctoral degree.<br /> o    Awards must be taken up by Autumn 2025-Spring 2026.<br /> o    Applicants must live within a reasonable distance of the University of Leeds whilst in receipt of this scholarship.<br />  </p>

<h2 class="heading">How to apply</h2>

<p>(if you want to make any changes to the process below please contact your Graduate School admissions team first)</p> <p>To apply for this scholarship opportunity applicants should complete an online application form and attach the following documentation to support their application. </p> <p>o    a full academic CV<br /> o    degree certificate and transcripts of marks<br /> o    Evidence that you meet the University's minimum English language requirements (if applicable)</p> <p>To help us identify that you are applying for this scholarship project please ensure you provide the following information on your application form;</p> <p>o    Select PhD in Medicine as your programme of study<br /> o    Give the full project title and name the supervisors listed in this advert<br /> o    For source of funding please state you are applying for a (NAME OF Scholarship)</p> <p>If English is not your first language, you must provide evidence that you meet the University's minimum English language requirements (below).</p> <p>As an international research-intensive university, we welcome students from all walks of life and from across the world. We foster an inclusive environment where all can flourish and prosper, and we are proud of our strong commitment to student education. Within the we are dedicated to diversifying our community and we welcome the unique contributions that individuals can bring, and particularly encourage applications from, but not limited to Black, Asian, people who belong to a minority ethnic community, people who identify as LGBT+; and people with disabilities. Applicants will always be selected based on merit and ability. </p>

<h2 class="heading heading--sm">Entry requirements</h2>

Applicants to this scholarship in the School of Dentistry should normally have an Undergraduate degree of 2:1 or above (or international equivalent) in a relevant subject area. A master’s degree is desirable, but not essential. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Admissions Team prior to making an application.

<h2 class="heading heading--sm">English language requirements</h2>

The minimum English language entry requirement for postgraduate research study in the School of Dentistry is an IELTS of 6.5 overall with at least 6.0 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid.

<h2 class="heading">Funding on offer</h2>

<p>One full funded full-time PhD scholarship is available in the School of Dentistry for a start in Autumn 2025-Spring 2026. The scholarship will cover UK tuition fees and attract a stipend of £20,780, subject to satisfactory progress. </p>

<h2 class="heading">Contact details</h2>

<p>For further information please contact the Graduate School Office<br /> e: <a href="mailto:EMAIL@leeds.ac.uk">fmhpgradmissions@leeds.ac.uk</a></p>