The prevention and diagnosis of central venous catheter-related infection

The potential source of CVC colonisation was assessed. Isolates of coagulase-negative staphylococci (CoNS) recovered from the skin and CVC components of 3 cardiothoracic surgery patients were characterised by pulsed-field gel electrophoresis (PFGE). The genetic heterogeneity of CoNS isolated from the skin was demonstrated and specific genotypes implicated in catheter colonisation. In addition, phenotypic and genotypic typing techniques were assessed for their ability to characterise strains of CoNS recovered from 33 patients who developed catheter-related bloodstream infection (CR-BSI) on a bone marrow transplant (BMT) unit and Siaphylococcus aureus recovered from 6 cardiothoracic surgery patients with surgical site infection (SSI) following median sternotomy. This epidemiological investigation revealed that common strains of CoNS and 51 aureus where not associated with infection in patients with CR-BSI or sternal SSI during the study period. Furthermore, there was no correlation between phenotypic and genotypic characterisation results. The variable expression of phenotypic traits within strains of staphylococci was evident whilst PFGE and randomly amplified polymorphic DNA (RAPD) were highly discriminatory for the molecular characterisation of S. aureus and CoNS. This was highlighted in 8 stem cell transplant (SCT) patients whereby it was demonstrated that routine identification and characterisation of CoNS by phenotypic techniques may not be adequate for the diagnosis of CR-BSI by current guidelines. The potential of the lipid S ELISA to facilitate the diagnosis of CR-BSI in 38 haematology/SCT patients and sternal SSI in 57 cardiothoracic surgery patients was also assessed. The ELISA proved to be a sensitive test for the rapid serodiagnosis of infection due to staphylococci in immunocompetent patients. The acridine orange leucocyte cytospin test (AOLC) was also evaluated for the rapid diagnosis of CR-BSI in 16 haematology/SCT patients with Hickman CVC in situ. Although the sensitivity of the test was low, it may provide a useful adjunct to conventional methods for the in situ sampling of catheters to predict and diagnose CR-BSI, preventing the unnecessary removal of CVC.

Aspects of the prevention and repair of chloride-induced corrosion of steel in concrete

Sodium formate, potassium acetate and a mixture of calcium and magnesium acetate (CMA) have all been identified as effective de-icing agents. In this project an attempt has been made to elucidate potentially deleterious effects of these substances on the durability of reinforced concrete. Aspects involving the corrosion behaviour of embedded steel along with the chemical and physical degradation of the cementitious matrix were studied. Ionic diffusion characteristics of deicer/pore solution systems in hardened cement paste were also studied since rates of ingress of deleterious agents into cement paste are commonly diffusion-controlled. It was found that all the compounds tested were generally non-corrosive to embedded steel, however, in a small number of cases potassium acetate did cause corrosion. Potassium acetate was also found to cause cracking in concrete and cement paste samples. CMA appeared to degrade hydrated cement paste although this was apparently less of a problem when commercial grade CMA was used in place of the reagent grade chemical. This was thought to be due to the insoluble material present in the commercial formulation forming a physical barrier between the concrete and the de-icing solution. With the test regimes used sodium formate was not seen to have any deleterious effect on the integrity of reinforced concrete. As a means of restoring the corrosion protective character of chloride-contaminated concrete the process of electrochemical chloride removal has been previously developed. Potential side-effects of this method and the effect of external electrolyte composition on chloride removal efficiency were investigated. It was seen that the composition of the external electrolyte has a significant effect on the amount of chloride removed. It was also found that, due to alterations to the composition of the C3A hydration reaction products, it was possible to remove bound chloride as well as that in the pore solution. The use of an external electrolyte containing lithium ions was also tried as a means of preventing cathodically-induced alkali-silica reaction in concretes containing potentially reactive aggregates. The results obtained were inconclusive and further practical development of this approach is needed.

Illness perceptions, beliefs and prevention of Type 2 Diabetes among British Pakistani mothers and young British Pakistani women

The prevalence rates of type2 diabetes mellitus (T2DM) continues to rise among British Pakistanis. The aim of this project was to explore T2DM perceptions and any preventative intentions among British Pakistani women and to discover whether they are doing anything to prevent the onset in themselves and their families. Initially a systematic review was conducted to investigate 20 existing prevention interventions and to assess their effectiveness (n=12,419). Mixed methods approach was adopted and three studies were conducted. The first study consisted of two focus groups with T2DM mothers (n=8) and three focus groups with non-T2DM mothers (n=17). The second study consisted of four focus groups young British Pakistani females (n=11). All focus groups were transcribed verbatim and analysed using thematic analysis. Following these a quantitative study was undertaken comprising of a questionnaire survey; 12 prevention-perception items (derived from the qualitative data) and the Illness-Perception Questionnaire Revised (IPQ-R) using participants from the same populations: T2DM mothers (n=41), non-T2DM mother (n=47) and young women (n=42). Results were analysed using multiple/hierarchical regression. The systematic review highlighted that the most effective prevention programmes focussed on behaviour and lifestyle with a combination of support and education to participants. The research studies demonstrated that T2DM was seen as an older person’s disease to be dealt with if/when it happens. T2DM mothers demonstrated knowledge and prevention understanding. There were non-significant relationships between prevention perceptions and T2DM illness perceptions across all three groups. The finding of this thesis emphasised that lifestyle interventions are crucial to aiding T2DM preventions as a good healthy diet and regular physical activity are the key components to T2DM prevention, and the importance of personal experience in perceived severity and lay-beliefs regarding T2DM and on family/cultural influences in British-Pakistanis. The findings of this project can be used to design culturally specific interventions towards preventing T2DM in the British Pakistani community.