UC San Diego

Catheter associated urinary tract infection (CAUTI) is a significant problem. Interdisciplinary teams have coordinated to address this problem, yet there is still a need for an adequate solution. Indwelling urinary catheters are at the root of prevalence of CAUTI. Urinary catheters with surfaces that are defenseless against the growth of infectious microorganisms, such as bacteria, are a risk to patients with urinary incontinence. This Master’s thesis describes the design and investigation of a passive electricidal urinary catheter surface. This entails a discussion of methods to prevent CAUTI with catheter coatings, in addition to methods used to formulate and adhere coatings. The design of composite coatings using polydimethyl siloxane (PDMS), with active materials zinc, silver, and/or silver oxide powders is disclosed, thereafter. These coatings are designed so that the active materials are well adhered and allowed to react in the presence of bodily fluids. The oxidation reduction reactions that occur between the dissimilar metals in solution has the capability to create an environment at the catheter surface that includes electric fields, microcurrents, changes in pH, and generation of heavy metal ions and hydrogen peroxide. This environment is similar to that of a zinc-silver galvanic cell, and has been found to alter the adhesion and proliferation of bacteria on surfaces and their ability to form dangerous biofilms. The composite coatings made in the lab were tested to determine their reactivity and biocidal effects. Methods used to quantify the generation of hydrogen peroxide, electric potentials, changes in pH, and inhibition of planktonic bacteria and biofilm in synthetic urine are discussed. The results of these tests show that the coatings are able to generate potentials and hydrogen peroxide in synthetic urine. Coatings containing combinations of zinc and silver oxide or silver and silver oxide have the greatest antimicrobial effects compared to controls. These coatings also inhibited biofilm as good as, if not better than, commercially available antimicrobial specimens.