Dissertation
Thermoelectric mitigation of Pseudomonas aeruginosa biofilms
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Spring 2023
DOI: 10.25820/etd.007041
Abstract
Healthcare associated infections on medical implants are a serious concern as they can lead to significant morbidity and mortality. These infections can occur when bacteria or other microorganisms attach to the surface of the implant and form a biofilm, which can be difficult to treat with antibiotics and requires multiple surgeries for removal of the infected implant, tissue debridement, and reimplantation of a new device. In-situ thermal elimination of the biofilm is a promising alternative to invasive surgeries. Thermal treatment requires remote delivery of heat at the implant/biofilm interface at a biofilm-eliminating thermal dose which may also cause damage to the tissue adjacent to the biofilm. This work introduces using thermoelectric technology for applying safer thermal shocks as a strategy that enables heating that can be immediately reversed to cool the shocked area and minimize tissue damage. This study used a thermoelectric device to investigate differences in efficacy of Pseudomonas aeruginosa biofilm elimination via thermoelectric surface heating vs previously studied immersion heating and determined the effect of post-thermal shock cooling on thermal susceptibility of the biofilm. Furthermore, a computational model was constructed to guide the design of a thermoelectric thermal shock delivery system. The findings suggest that surface heating is not equivalent to immersion heating, likely due to bacteria fleeing the surface and later returning to avoid some of the thermal exposure. This dispersion from and resettlement to the biofilm is an equilibrium process. A rapid thermally induced spike in bacterial dispersion suggested that although equilibrium between the rates may be temperature independent, the rates themselves may be highly temperature dependent. Studying the kinetics of biofilm/tissue inactivation revealed that inactivation of Pseudomonas aeruginosa biofilm occurs at a faster rate compared to damage of muscle tissue. Moreover, it was found that immediate post-shock cooling can be applied to minimize thermal damage without risking the efficacy of thermal destruction of biofilms. Computational modeling of thermoelectric thermal shocks showed that a shorter thermal shock at a higher temperature leads to significantly less thermal damage and that the thermoelectric device may significantly reduce the thermal damage under circumstances where the tissue has poor/impaired blood perfusion.
Details
- Title: Subtitle
- Thermoelectric mitigation of Pseudomonas aeruginosa biofilms
- Creators
- Parham Parnian
- Contributors
- Eric E Nuxoll (Advisor)Syed Mubeen (Committee Member)David W. Murhammer (Committee Member)David G. Rethwisch (Committee Member)Kristan S. Worthington (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Chemical and Biochemical Engineering
- Date degree season
- Spring 2023
- Publisher
- University of Iowa
- DOI
- 10.25820/etd.007041
- Number of pages
- xiii, 132 pages
- Copyright
- Copyright 2023 Parham Parnian
- Language
- English
- Date submitted
- 04/24/2023
- Date approved
- 05/09/2023
- Description illustrations
- illustrations, tables, graphs
- Description bibliographic
- Includes bibliographical references (pages 92-101).
- Public Abstract (ETD)
- In the past sixty years advancements of medical implants have been remarkable leading to the creation of an impressive range of implantable medical devices to treat numerous illnesses. Despite all the developments in this field, implant infections account for more than one million healthcare associated infections. Most of these infections are caused by a community of bacteria surrounded by a self-produced structure (biofilm) that resists our immune system and antibiotics. This feature makes biofilms difficult to treat requiring costly, lengthy, and risky invasive surgeries for implant removal and reimplantation of a new device. Thermal elimination of these infections is a non-invasive alternative treatment that kills the bacteria by heating them up and is possible via wireless heating of the implant’s surface. The downside of thermal treatment is the damage caused to the tissue next to the biofilm. This work proposed using thermoelectric technology which enables heating that can be immediately reversed to cool the shocked area and minimize tissue damage. The feasibility of biofilm elimination via thermoelectric thermal shock followed by cooling was investigated at different temperatures and exposure times and a computational model was used to predict the damage caused from thermal exposure and guide the design of a thermoelectric setup that can provide safer thermal treatment. It was found that thermoelectric heating and cooling can eliminate the biofilm to non-quantifiable levels. Also, the model predictions showed higher temperatures for shorter amounts of times caused less tissue damage and that thermoelectric technology can minimize this damage when the affected tissue lacks sufficient blood flow to carry the heat away.
- Academic Unit
- Chemical and Biochemical Engineering
- Record Identifier
- 9984437257802771
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