The development of a fluorescent / colorimetric marker spray for the rapid detection of MRSA / MSSA

Malik, Samerah (2012) The development of a fluorescent / colorimetric marker spray for the rapid detection of MRSA / MSSA. (MSc(R) thesis), Kingston University, .


Methicillin-resistant 'staphylococcus aureus' (MRSA) is commonly referred to as a 'super bug', presenting a major problem within the health care environment, as this highly infectious disease requires expensive antibiotic treatment and a lengthier stay in a hospital, which further puts pressure on health-care based resources. The main reason for the spread of this infectious agent, is that there exists no rapid detection system that can be used on a large scale directly on surfaces / equipment / staff / patients at the point of care, to highlight infected areas. Deep cleaning procedures are currently systematic; however rapid detection method could allow targeting of these specific areas and thereby reduce the risk of infection spreading. A similar issue occurs with undetected methicillin sensitive 'staphylococcus aureus' (MSSA), which can be just as infectious as MRSA, even if more easily treated. This project involves the proof of concept and development of a non-lab based, rapid detection system. By improving on a coumarin dye system first reported in the 1970s, based on compound Butoxycarbonyl - Valine - Proline - Arginine - Methyl Coumarin (Boc-Val-Pro-Arg-Methyl Coumarin), The concept of this system is based on staphylothrombin's biological action, it recognises a specific tripeptide sequence and cleaves after the arginine residue releasing a free fluorophore, detected via a fluorescent shift. Modification to improve on this system involves the replacement of the poorly sensitive, low extinction coefficient fluorophore, methyl coumarin, with the opposite, a highly sensitive chromophore with a higher extinction coefficient that on release is accompanied with a visual colour change, promoting the desired rapid qualitative result. Reported are the chromophores tested for their suitability in our proposed dye system. Results suggest Rhodamine 110 is the most suitable and synthetic work was attempted following a convergent synthetic plan after successful isolation of the tripeptide sequence, not previously reported. Following successful synthesis of the tripeptide - chromophore conjugate, problems associated with the most suitable chromophore, Rhodamine 110 were highlighted and other approaches have been reported in order to eliminate these problems and ultimately develop the proposed system.

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