Biofilms – What You Need to Know
No, we’re not talking about biographical films depicting the life and times of famous individuals. We’re referring to a community of microorganisms that typically forms a thin, slimy layer on a given surface.
Role and implications of biofilms
Biofilms protect bacteria, enabling them to survive under adverse environmental conditions. Biofilm bacteria can withstand host immune responses and are highly resistant to antibiotics and disinfectants. The presence of biofilms during infections means that prevention, diagnosis and treatment have to be approached differently.
This natural method by which bacteria adhere to surfaces greatly changes the way in which they can be disinfected, which is why recurrent contaminations of some surfaces have to be managed carefully.
How microorganisms survive
In nature, microorganisms go “with the flow.” They go wherever the fluid surrounding them goes. When they encounter a surface, however, they can sometimes get stuck to it – at which point they will focus their energy elsewhere. This reaction will depend on their environment. If nutrients abound, the microorganisms will grow and multiply. If nutrients are beginning to run out, the microorganisms will form a cocoon to protect themselves and will build a viable community. This cocoon, called an “extracellular polymeric matrix,” is the main difference between planktonic bacteria and a biofilm.
4 protective mechanisms
This difference may seem insignificant, but it has huge implications for the microorganisms and for how surfaces containing a biofilm may be disinfected. That’s because the microorganisms contained inside a biofilm are protected from the environment. The following four protective mechanisms are widely accepted:
- The matrix forms a physical barrier that blocks hazardous agents from reaching the microorganisms.
- The closer proximity of the bacteria makes it easier for them to enables them to better communicate with one another to cope with stress.
- Metabolic activity is reduced, which in turn may reduce the bacteria’s susceptibility to antimicrobial agents.
- The surviving (persister) cells accumulate in the biofilm, since they revert less readily and are physically retained by the biofilm matrix.
These four protective mechanisms increase the bacteria’s resistance to the most widely used disinfectants. This creates a false sense of security, which increases the risk of infection.
What products work against biofilms?
When manufacturers seek approval for the efficacy claims of a disinfectant, they must show that the results have been obtained through a variety of methods. Although these methods test the rate at which planktonic bacteria are destroyed, they do not take into account the bacteria that are hiding inside the biofilm. What’s more, microorganisms that are unable to form a biofilm on their own (such as viruses) can hide inside an existing biofilm, which increases their protection. In other words, even if a product demonstrates excellent results for eliminating bacteria, it does not necessarily mean it will be effective against biofilms.
Attack the root problem behind biofilms
Various strategies have been devised to attack biofilms, but to halt biofilm contamination, both the surface of the biofilm and the microorganisms inside it must be destroyed. If you kill the bacteria but leave the biofilm in place, you could create a new home for other bacteria, which will quickly form another biofilm. On the other hand, if you eliminate the biofilm without killing the bacteria, they can spread everywhere.
