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The University of Southampton
Biological Sciences

Research project: Development of novel methods to assess the viability and infectivity of pathogens in biofilms found in drinking water supply systems.

Currently Active: 

This project aims to use molecular techniques to improve the detection of viable but nonculturable (VBNC) bacterial pathogens in drinking water systems and is also exploring the potential to assess the infectivity of VBNC pathogens using the new methods of assessment.

Biofilms can form on pipe and tank walls associated with mains drinking water supply systems and building water supplies. Previous work has demonstrated how bacterial pathogens can be incorporated into biofilm structures and survive for extended periods of time. The biofilm itself can create a protective niche for such pathogens, protecting them from mechanical and chemical attack. Earlier work has shown how both non-spore forming and spore forming species can display high resistance to commonly used disinfectants and how standard methods of detection (primarily culture-based) are ineffective at assessing the viability of these pathogens. When in a stressful environment, bacteria can enter a viable but nonculturable (VBNC) state, where they are unable to grow on highly nutritious or selective media but are still viable and potentially infective.
The presence of these VBNC cells has been clearly shown using alternative methods but there is no technique currently available which can accurately measure and quantify the entire viable population. In addition, it is important to be able to show that these VBNC cells retain their infectivity to be able to assess the public health risk they pose. We propose developing the propidium monoazide/real-time PCR (PMA-PCR) technique for use in detecting and quantifying VBNC bacteria. This is a highly sensitive and specific molecular technique which has been used on different sample types. Preliminary work has indicated that this could be a valuable approach for the rapid, sensitive and specific detection and quantification of VBNC pathogens. To determine the infectivity state of VBNC bacteria, we propose using a novel model system.
The development of these techniques will aid in the assessment of public health risks that can be posed by such pathogens and the improvement of routine and emergency disinfection and decontamination protocols.


Funded by Defra for period 01/10/2010 – 31/03/2011


Principal Investigators: Professor C. W. Keevil, Dr S. A. Wilks

Research Fellow: Dr J. C. Warner

Related research groups

Molecular and Cellular Biosciences
Environmental Biosciences
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