What are Bacterial Biofilms? A Six Minute Montage. - I think there's an increasing recognition that biofilms play a role in chronic diseases. And the reason for that is that biofilms are very difficult to eradicate. They live on surfaces. They produce extracellular materials that can defend themselves against human immune cells or antibiotics. And therefore, they're very difficult to remove. And once they form on a surface, they're very difficult for your body or for drugs to kill them. - So it's only been within the past, really, 15 years that the medical community has recognized the existence of biofilm bacteria as fundamentally separate and distinct from planktonic bacteria. - Bacteria come together when they're threatened. When you have a situation where bacteria are treated with antibiotics that can kill them or when a strong immune system responds to a bacteria by producing cytokines or chemokines or other agents that are able to destroy the bacteria and to eliminate them from the body, these bacteria have a choice. They can either stay as an individual bacteria and die or they can change their form and instead of being a planktonic bacteria, form biofilms. - Acute bacterial infections and chronic bacterial infections are very different. Acute bacterial infections are caused by planktonic, that is, bacteria that are swimming freely, each bacteria is essentially a single-celled organism. Chronic infections, for the most part, are caused by bacterial biofilms. And the bacterial biofilm is, in essence, a multicellular organism so that each individual bacterium within the biofilm is analogous to each individual cell in your body. And so they are actually functioning as a single organism. And it's the adoption of the biofilm mode of growth that provides for what we say chronicity or persistence. - We have done studies in which we have grown biofilms and then tried to add, you know, penicillin, gentamicin, some standard-type antibacterial agent. And we're not seeing it do anything. - They are very difficult to eradicate because they don't grow rapidly. And most antibiotics kill organisms that are growing. And they will not kill organisms that are not growing. So these organism can faster in a particular area. For example, a heart valve, endocarditis is a biofilm of organisms on that heart valve. - Examples of this can include infections of bone, infections of your heart valves, infection of the urinary tract in which bacteria can colonize these surfaces in the human body and live there for long periods of time. - Now what we know about these communities is that they-- it takes such a greater concentration of antibiotics to get rid of them that it is not indicated. You're talking about anywhere from 500 to 5,000 times the concentration that normally is the minimum inhibitory concentration of antibiotic that it takes to kill bacteria in a biofilm. - The link between biofilms and antibiotic resistant bacteria is quite close in that biofilms, because of the presence of persister cells and being able to trade genes between each other, can often have an increased level of antibiotic resistance. And so I think that moving forward, the type of technologies we need to develop and the type of research that we need to do needs to really focus on both of these problems together-- biofilms as one distinct entity, but also as antibiotic resistance and how they interplay with each other to cause human disease. - Now what this says is that clinicians have to be much more careful and patients have to be much more vigilant about being in a hospital setting, about having surgery. Because these are all times and areas where one can pick up bacteria that can lead to biofilms. NARRATOR: The life cycle begins when bacteria enter the bloodstream from various infection routes and evade the immune system or antibiotics. Formation begins with attachment of planktonic bacteria to the surface preconditioned with proteins from the host immune system. Irreversible attachment to host proteins signals the bacteria to create biofilm and is the first committed step of biofilm growth. The bacteria anchor themselves permanently using cell adhesion structures such as pili and receptors called epitopes. This encourages new bacteria to attach to newly arriving cells, providing adhesion sites and building the protective matrix of the biofilm structure. Cells now communicate via quorum sensing and use small molecules to regulate gene expression within the bacterium. The community grows through both cell division and recruitment. The development of this complex biofilm makes the community resistant to the immune response and antibiotics. It may include diverse species of bacterias, yeasts, minerals, and host proteins. Recruited neutrophils result in a cascade of inflammatory cytokines and host proteases. These damage tissue and regulate fluid accumulation in exudate providing nutrients. Bacteria now exist in multiple forms and metabolic states. Now a different phenotype, both physically and metabolically, it has the survival advantages of diversity and multiple defenses. The life cycle continues as fragments or planktonic bacteria are released to re-infect the human host.