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A dissertation in partial compliance with the requirements for a Master's Degree in Technology: Homoeopathy, Technikon Natal, 2002. / The aim of this study was to establish the effect of Thymus vulgaris tincture prepared in 43% ethanol and 70% ethanol in comparison to 43% ethanol and 70% ethanol only upon Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis, Escherichia coli and Enterococcus faecalis, using a disc diffusion method, and to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MEC) of Thymus vulgaris tincture in respect of these bacteria. Mueller-Hinton agar plates were streaked with saline test cultures adjusted to the 0.5 McFarland Equivalence Turbidity Standard. Five sterile filter paper discs 5mm in diameter were placed on each plate. These filter paper discs were impregnated with 10111of the test or control substances using a micropipette. The plates were incubated at 3TC for 18 hours. The diameters of the zones of inhibition of the bacterial growth around the discs were measured. This data was used to look for inter-group change by means of the Mann- Whitney Test between the test and control subgroups in both group A and group B. The means and standard deviations of each of the groups were compared in order to look for possible trends if the p-value of each group was insignificant. Il Thymus vulgaris tincture in 43% ethanol produced significant inhibitory effects in comparison to the 43% ethanol control upon all the bacteria tested. Thymus vulgaris tincture in 70% ethanol produced significant inhibitory effects in comparison to the / M

As a continued study on combined use of different antibacterial chemistries, N-chloramine and short chain Quaternary ammonium compound (QAC) were immobilized on modified poly (ethylene terephthalate) (PET) surface in various ratios via “click” chemistry. In this study, contribution of surface bound QAC to the conversion of cyclic and acyclic N-H to N-Cl, fastest recharging chlorination as well as the most effective antibacterial efficacy was investigated. Surface bound positive charge at the density of 8.4x1016charges/cm2 achieved highest equilibrium conversion and facilitated a nine-fold increase in conversion of sterically hindered acyclic N-H to N-Cl from 0.39 to 3.92%. Within the range of 2.8x1016 to 8.4x1016charges/cm2, highest active chlorine loading within first five minutes of chlorination was observed on sample loaded with 4.6x1016charges/cm2.As it comes to PET surface grafted with a cyclic N-chloramine precursor, the presence of 2x1016charges/cm2 enabled a five-fold increase in the conversion of cyclic N-H to N-Cl. The highest biocidal efficacy was observed for sample loaded with cyclic N-chloramine/QAC 17.2:10 which presented total kill of E.coli (5.8 log reduction) in 10 minutes compared to 1.9 log reduction for other ratios (22.8/10, 75.5/10) tested at a similar level of active chlorine(223±6ppm respectively). / October 2016

Hospital-acquired infections are a significant contributor to clinically-related morbidity and mortality. The majority of these infections are associated with the use of invasive medical devices, where urinary catheters account for ~36% of cases. Current preventative strategies have shown short-term (<7 days) success, however their long-term (>28 days) efficacy is unclear. This thesis explores the use of solution-cast polyurethane nanocomposite (PUNC) materials for antimicrobial drug delivery in urinary applications. It is hypothesised that the enhanced barrier properties of PUNCs, afforded by the incorporation of well-dispersed nanoinclusions, would allow for the sustained release of an antimicrobial agent. The objectives of this research were to investigate the antibacterial, mechanical and barrier properties of PUNCs incorporating various silicates modified using antimicrobials, hypothesised to also act as dispersing agents. Organically modified silicates (OMS) were prepared at 110%, 200% and 300% cationic exchange capacity (CEC) using the biocide, chlorhexidine diacetate (CHX), which was hypothesised to perform the dual functions; dispersant and antibacterial agent. Resulting OMS were incorporated at 1wt% and 5wt% loadings into a PU matrix to produce PUNCs; PEU-CHX1.1MMT, PEU-CHX2.0MMT, and PEU-CHX3.0MMT, respectively. CHX performed well as a dispersant, producing intercalated to partially exfoliated PUNCS. Antibacterial activity was dependent on OMS type and loading. PEU-CHX1.1MMT materials had poor antibacterial properties, but the addition of free CHX into the materials significantly improved their efficacy, demonstrating long-term sterility in an in vitro urinary tract (UT) model. PEU-CHX2.0MMT and PEU-CHX3.0MMT at 5wt% OMS loadings had partially exfoliated structures and excellent antibacterial activity. Cytotoxicity was evident in all materials, although to a lesser extent in the latter. Overall, intermediate OMS loadings of CHX2.0MMT would be expected to produce PUNCs with favourable antibacterial activity and cytocompatibility. PUNC drug-release profiles demonstrated sustained release compared to pristine PU, indicative of enhanced barrier properties. Their ultimate tensile properties decreased with increased OMS loading or addition of free CHX.Higher cationic-exchanged OMS caused significant reductions in strain. Young's modulus increased in response to higher %CEC OMS and loading. PUNCs show promise as antibacterial biomaterials for long-term urinary applications, where antimicrobial release and mechanical properties can be modulated through organic modification and OMS loading.

Thesis (M.P.H.)--University of Queensland. / Includes bibliographical references.