Paper BI-MoM5
Why do Bacteria Stick to Some Surfaces and Not Others? Characterisation of the Behaviour of Motile Bacteria at and above the Surface of Materials

Monday, December 12, 2016, 9:20 am, Room Milo

Antimicrobial resistance has been recognised as a pressing problem by the WHO, the UK government review [Jim O’Neill 2014] predicting a financial impact equal to cancer by 2050 and most recently a unanimous declaration by the UN General Assembly. Infections associated with medial devices are a significant contribution to this challenge. Hook et al. used high throughput screening to discover a new class of polymer with resistance to biofilm formation correlating with the chemistry of the uppermost nanometer of the material. [Nature Biotechnology 2012] Whilst a device using this material is progressing to regulatory approval for use in man, we are exploring the mechanism by which these work to enable us to develop improved devices.

Microorganisms cannot be approximated to inert objects since they possess surface responsive appendages such as flagella, which enable them to swim, pili that confer twitching motility and fimbriae that mediate surface attachment in response to surfaces. These ‘devices‘ are in turn coupled to sophisticated signal transduction mechanisms that facilitate integration of multiple local environmental parameters at both single cell and population levels. Many of these sensory systems are postulated to contribute to surface sensing. As an example of the complexity of these processes, the opportunistic pathogen Pseudomonas aeruginosa has over 60 two-component sensor kinase response regulator systems involved in environmental adaptation.

We believe that bacterial decision-making is key to determining whether a surface is colonised or not. I will present the early results from our optical microscopy investigations of how individual bacterial cells respond to surfaces. We have developed a novel microscope that collects temporal 3D information on cell position using both holography and remote scanning microscopy. Surface tracking can be simultaneously achieved using DIC, TIRF and TIR microscopy. This allows us to track not only the motion of single cells at the surface, but also their approach to and behaviour after contact with the surface. We will combine these findings with our understanding of the surface chemistry-attachment relationships for certain subsets of materials and attachment regimes with in situ chemical analysis to build a complete description of this complex biointerface and the response of bacteria to it. This information is crucial in determining how bacteria behave with respect to defined surfaces and has important implications for the prevention of device centred infections and the development of the next generation of biofilm resistant surfaces.