Antibacterial Surfaces

Bacteria and other microorganisms affect all aspects of our life. They are key players in the biogeochemical cycles and provide nutrients for growth of higher organisms. They are also a major challenge as infectious agents of man, animals and plants. Until a few decades ago, most studies of bacteria were done in liquid mono-cultures where the organisms grew as planktonic cells. However, it was realized that the dominant mode of microbial growth is as adhered cells on biotic or abiotic surfaces, so-called biofilms. These consist of the microbes, water and polymeric substances (proteins, DNA, polysaccharides). Microorganisms in biofilms are often more tolerant to antimicrobials such as antibiotics and disinfectants and, hence can constitute a continuous reservoir of contamination and infection. Thus, preventing or reducing microbial adhesion to surfaces is key in infection control and in food and pharma processing. However, microbial biofilms may also be beneficial and therefore enhancing biofilm formation is important in for instance biological sewage treatment or in plant biocontrol where beneficial bacteria colonize the roots and offer plant protection.

Structured, surface-attached biofilms are rarely observed in chronic infections. Rather, chronic biofilm infections constitute a highly complex environment where non-attached, aggregated biofilms are heterogeneously distributed within highly inflamed mucus or pus. Foreign body related infections are an exception to this and bacterial biofilms have been observed surrounding pacemaker wires, stents and catheters. In these instances, biofilm may build up in the interface between the foreign body and host tissue, though often to a lesser extent directly on the surface itself. In this talk, I will give an overview of the current understanding reguarding biofilm in chronic infections, both unattached and surface bound. Additionally, I will compare and contrast one of the most widely used in vitro biofilm models with relevant in vivo findings.

Biofilms are of great importance in infection control and healthcare-associated infections. Biofilms develop on medical device surfaces and several strategies are being developed and tested to minimize the risk. Selected projects focusing on prevention, diagnosis and treatment of surface related infections will be presented showing data from in vitro and in vivo systems.

Infectious control is facing more and more challenges with the development of resistance in microbes. Traditional biocides and methods are having difficulty handling the growing global threat from listeria in food to hospital acquired infections (HAI). These microbes cost society increasing amounts. Therefore, this allows for a new view on infectious control using state of the art technology for this new class of biocides.

The emergence and spread of antibiotic resistance and multidrug-resistant pathogenic bacteria is an increasing challenge in health care settings. Bacteria may spread via inert surfaces and therefore antimicrobial materials are being developed as a potential strategy for reducing the contamination of frequently touched surfaces such as door handles and furniture in hospitals. Her project has demonstrated that a novel electroplated copper-silver alloy on stainless steel has higher antimicrobial activity than the individual metals in standardized adhesion tests, suggesting it as a promising tool for controlling the spread of pathogens in hospitals. The direct contact between the alloy surface and bacteria induces a significant pH increase, which could play a key role in the antibacterial mechanism. The talk will describe the copper-silver coating and its ways of action.

Fighting bacteria and biofilm related infections has proven to be a challenging effort which requires multiplex approaches. Reducing bacterial adhesion through surface modification is an attractive tool due to the low toxicity and low risk of inducing resistance. To achieve this, we need to better understand how surface properties affect bacterial adhesion, and develop tools to study and evaluate adhesion of bacteria and growth of biofilm. In this talk, Guanghong Zeng is going to talk about using atomic force microscopy to study adhesion of bacterial cells on various surface, and its applications in studying the role of bacterial surface molecules, and in evaluating antifouling coatings.

Studies of microbial pathogenesis and drug development require the use of bot in vitro an in vivo methodology. Methods are presented here, that are used in order to understand bacterial binding capacity and the molecular mechanisms behind it that result in infection.

Medical devices: Novel technologies enable development of advanced antimicrobial medical devices such as coated surfaces and materials. In spite of few written requirements, FDA expects that test methods used to produce data in support of regulatory filings are validated. Microbiological methods are no exception, but these methods are widely accepted as being extremely variable and hence difficult to validate. In this talk, considerations, pitfalls and other experiences from designing microbiological test methods in support of antimicrobial technologies are discussed.