Developing a novel fluorescent imaging point-of-care diagnostic for Mycobacteria

Abstract

Tuberculosis (TB) is a major infective cause of death globally, with the greatest burden falling to those countries with lower socioeconomic status. The World Health Organisation aims to End TB by 2035, but improved point-of-care diagnostics are needed to make this happen. In particular, this will help rural populations in low and middle income countries to access diagnostics easily and more quickly, thereby reducing the spread of the disease. Smear microscopy has been the cornerstone of TB diagnostics for a century but processing techniques, biosafety and the microscopy infrastructure make it difficult to translate directly to the point-of-care. This thesis addresses the development of a novel point of care diagnostic test for the rural, low and middle income region. Three issues have been addressed independently including the improved labelling of Mycobacterium species, a novel filtering lens for use with a smartphone microscope and the design of a new sputum collecting and imaging device.

It has been demonstrated that a novel fluorescent stain that is specific for Mycobacterium can label within seconds, without further wash or processing steps. The rate of labelling is dependent on the environment that the Mycobacteria is exposed to, with desiccating conditions resulting in the quickest labelling. The development of an integrated filtering lens, which combines both a lens and filter into one component has enabled fluorescent Mycobacterium to be imaged with a smartphone microscopy system.

The designed device, that can capture a sputum sample, process and image it, would negate the need for screening samples to be sent away to microscopy level suites. The design process achieved the designs, incorporated the novel fluorescent stains and the integrated filtering lens.

The work demonstrated in this thesis shows a potential solution for TB diagnostics at the POC. While further work is needed in each of the areas discussed, such as manufacturing and iterating the final design, a device similar to the one proposed would disrupt the POC diagnostic space. However, the biggest challenge for all POC diagnostics is integrating technology into healthcare systems and embedding it in local culture so that patients and healthcare providers want to use the test. Collaborating and working in partnership will be the key to any TB POC future success.