Date of Award

5-2016

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Biology

Thesis Sponsor/Dissertation Chair/Project Chair

Lee H Lee

Committee Member

John Gaynor

Committee Member

Ann DiLorenzo

Abstract

Prosthetic arthroplasty may be a life changing event for better or worse. The integrity of bone cartilages such as the lateral and medial meniscus found between the femur and tibia may degrade over time due to natural causes which may eventually result in bone on bone exposure causing excruciating pain. Prosthetics are used to replace the cartilage and bone damage using femoral and tibial component and a plastic spacer. A small percentage of all orthopedic replacement surgeries may lead to infections. These infections are caused by biofilm forming bacteria which allows bacteria to attach to abiotic surfaces and mature as a colony with increase resistance to stress so it can eventually disperse and continue propagating. This particular study focuses on a novel solution in targeting prosthetic joint infections by evaluating antimicrobial properties of green tea polyphenols (GTP) and its derivatives, epigallocatechin gallate (EGCG), lipophilic tea polyphenol (LTP) and epigallocatechin gallate-stearate (EGCG-S), on bacteria species common in prosthetic joint infections such as Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis. Crystal violet and Congo red assays were used to quantitatively and qualitatively were used to assess the properties of tea polyphenol derivatives on the gram-negative and gram-positive bacteria known in this study. The results indicate that each tea polyphenol derivative alone have strong inhibitory effects on inhibiting biofilm formation, particularly EGCG-S and LTP at a dose-dependent relationship. The colony forming unit evaluation suggests that both EGCG-S and LTP can reduce the cell viability of all three bacteria, particularly well at a concentration of 250ug/mL at 96-100% inhibition. Microscopic observations using scanning electron microscopy and fluorescent microscopy reveal changes to the morphology, reduced cell density and reduced cell surface integrity. When the bacteria were observed in a competitive growth study with each species, results were similar in biofilm inhibition at 96-100% and cell viability at 72-99% which suggests that EGCG-S and LTP may be a potential solution in targeting majority of bacteria species found in prosthetic joint infections. The current infected prosthetic irrigation and debridement protocol was also tested against tea polyphenol derivative and results show at a concentration of 250ug/mL of EGCG-S is as effective as the current concentration of antibiotics used. Overall, these results indicate that the nature derived compound known as EGCG-S and LTP may be useful as an antimicrobial agent on bacteria species most common to prosthetic joint infections. The results suggests that EGCG-S can be used as an antimicrobial agent to prevent infection at the primary stage of recovery during initial wound closure to reduce or eliminate acute infections. This may also be implemented into treating chronic infections to reduce patients reentering surgery for second stage implant removal which could ultimately lead to complications under anesthetics, during surgical operations, and recovery.

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