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No description available.

Chlamydia trachomatis (Chlamydia) is the most common sexually transmitted infection diagnosed in genitourinary medicine (GUM) clinics and affects one in ten sexually active young people. Neisseria gonorrhoeae (gonorrhoea) is the second most common. They are asymptomatic in at least three-quarters of patients. Untreated infection can lead to serious health problems; including pelvic inflammatory disease and infertility in women. In men, it can cause urethritis and Reiter‟s Syndrome (arthritis). The number of diagnoses of uncomplicated chlamydia in GUM clinics in England increased by 288% between 1995 and 20061. Co infection with chlamydia and gonorrhoea is not uncommon. Up to half of patients diagnosed may be infected with both pathogens and, therefore, it is important to test sexually active individuals for both chlamydia and gonorrhoea using a multiplex system2. Electrochemical detection of specific DNA sequences offers advantages over established fluorescence techniques; including cost and ease of miniaturisation. The electrochemical gene sensor described here uniquely utilises enzymatic T7 Exonuclease digestion to generate ferrocenylated oligonucleotide fragments in a matched (gene sequence presence) sensor. These fragments exhibit a characteristically high response upon electrochemical analysis, using Differential Pulse Voltammetry and have been designed based on the ability to „tune‟ the oxidation potential of ferrocene by using electron-withdrawing and electron-donating substituent groups. Ferrocenylated oligonucleotide labels have been synthesised, each with a characteristic oxidation potential. Results from a study of the adsorption and electron transfer kinetics of T7 exonuclease - digested and undigested oligonucleotide redox probes at screen-printed carbon paste electrode (SCPE) surfaces will be considered as a basis for the assay discrimination. The high selectivity of the T7 Exonuclease digest is demonstrated using the ferrocenylated oligonucleotides and a triplex genomic electrochemical assay for the detection of Chlamydia trachomatis, Neisseria gonorrhoeae and the human 7 beta-actin gene as an internal control for the assay using clinical samples will be presented.

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Sexually transmitted infections impose a huge burden on public health. The epidemic trajectories of such infections form part of a complex system of pathogen transmission, and are dependent on both pathogen characteristics and the structure and dynamics of the underlying sexual contact network. This thesis uses a dynamic network model which realistically represents human sexual contact dynamics in order to investigate the interactions be- tween these factors via three different approaches. Firstly, a transmission model is used to evaluate the role of pathogen du- ration of infectiousness in shaping the effective network over which an STI may spread. This allows us to examine the way in which the importance of different individual-level risk factors (such as number of sexual partners over five years) differs based on pathogen properties. Next, we expand this model to include evolution of a pathogen's genetic sequence, in order to study the extent to which population structure affects the structure of phylogenetic trees resulting from sampled sequences. Finally, we use this same transmission and evolution model to look at the skyline method of reconstructing past changes in effective population size, in order to estimate the number of sequence samples needed to be able to distinguish between a stable and a growing pathogen population and to ~ investigate the effect of network dynamics on the accuracy of this method.

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This thesis brings together 118 published studies on the microbiology of sexually transmitted diseases resulting from work performed in the University of Edinburgh Department of Medical Microbiology between 1973 and 1995. The main aim of these studies was to improve microbiological aspects of the diagnosis and management of syphilis and gonorrhoea. The earliest publication on syphilis serology was the first to recommend the use of a specific treponemal antigen test, the <I>Treponema pallidum</I> haemagglutination assay (TPHA) for routine screening. As a result of this study a screening schedule comprising the Venereal Diseases Research Laboratory (VDRL) and TPHA tests was introduced into routine practice in late 1973. Soon the same screening schedule was widely adopted in the United Kingdom and Europe. Appreciating the importance of computerised and automation I validated and standardised a prototype commercial enzyme immunoassay (EIA) as a single serological screening test and demonstrated that this gave a performance comparable to screening with the VDRL and TPHA tests while being suitable for automation and electronic report generation. Screening for syphilis by EIA is now becoming widespread throughout Europe. Because false positive EIA reactions may also show reactivity in the FTA-abs test, immunoblotting was evaluated as a confirmatory test. The possibility of syphilis reactivation and loss of treponemal markers in patients co-infected with HIV were also studied.

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