Preparation of dual-action germinant-biocide smart polymer and soluble agent for the elimination of c. difficile spores

Abstract

Clostridium difficile is a spore-forming, gram positive bacteria responsible for causing Clostridium difficile infection (CDI), the main symptom of which is diarrhoea. It can also cause serious symptoms, for example, pseudomembranous colitis, toxic megacolon and death. CDI spreads through the ingestion of C. difficile spores, which are very resistant to cleaning products and can survive on surfaces for many months. Little is known about the germination of C. difficile spores; taurocholic acid, a bile acid found naturally in the gut is one of the known germinants, but the exact mechanism of germination is unknown. Other bile acids, such as cholic acid have shown germinating ability, but to a lesser extent. The aim of this PhD was to create a polymer surface that forced the germination of the C. difficile spores upon contact, then to kill the resulting more susceptible vegetative cell. A known germinant of C. difficile spores, cholic acid, was derivatised at the carboxyl group in a flexible synthesis to give a range of carboxamide analogues terminating in a quaternised amino function, with or without a polymerisable function. The attachment of polymerisable groups at the hydroxyl functions was also explored. The cholic acid monomers proved to be resistant to polymerisation. Of the monomeric compounds, however, nine exhibited C. difficile spore-germinating activity, two had either sporicidal or germinating and antimicrobial abilities and two other compounds had germinating and sporicidal and/or antimicrobial activity. The results for this series of compounds indicate that germination of C. difficile spores is favoured by the presence of a quaternary ammonium function and a two- to four-carbon chain between the cholamide carbonyl and the quaternary centre. Overall, eleven new compounds exhibited activity against C. difficile spores. The incorporation of these compounds into a polymer surface or disinfectant spray has the potential to reduce the risk of infection of CDI by eliminating C. difficile from surfaces, in both healthcare and community based settings.