The dirt on biofilm

Thursday, September 29, 2016

Biofilm—slimy clumps of bacteria that settle onto surfaces—has been a growing concern in Canadian facilities because it can be a threat to occupants. In fact, it’s considered a leading cause of hospital acquired infections (HAI), can grow on any type of surface and is difficult to stop.

To better understand biofilm and learn ways to eliminate it, Robert Kravitz, former building service contractor and now writer for the professional cleaning and building industries, delves into the topic and interviews Matt Montag, distribution sales manager for CleanCore, manufacturers of aqueous ozone cleaning systems for the professional cleaning industry.

What is biofilm?

Biofilm is an assemblage of microbial cells that stick together and adhere to surfaces, like a dense glue cohesive. Within it are huge numbers of pathogens, mostly bacteria. Because of this, some public health officials refer to biofilm as “bacterial cities.” Biofilm isn’t necessarily bad, but when it is, it can cause serious health problems. Biofilm was first reported in 1684 by Antonie van Leeuwenhoek, a Dutch scientist who found a huge accumulation of microorganisms in dental plaque. While people usually hear about biofilm in context to human teeth, it can now be typically found on human teeth, it can now be found on a variety of surfaces—from floors and counters to sinks and even dog food and water bowls.

Where can biofilm be found?

Biofilm can be found everywhere, often in dry, unexpected areas of a facility. But for the most part, it needs moisture to survive.

“That’s why we might find it on rocks near a waterway or in spas and jacuzzis where water circulates,” says Montag. “We also find biofilm on surfaces that are frequently damp inside facilities, such as counters in a restroom or a food service area, locker room floors, restroom fixtures, and so on.”

Can you see biofilm on a surface?

When biofilm first forms you cannot see it, except under a microscope. However, as it grows and becomes larger, there is usually discoloration that occurs on the surface where it is attached. Often, it takes on a brown or pink color, but this can vary.

Is it hard to remove?

“Biofilm is hard to remove, and as the individual cells of bacteria and pathogens grow, they weave and interconnect,” says Montag. “As this happens, a sticky matter develops, which then bonds to just about any surface. Think of biofilm on our teeth. If it were easy to remove, we could just brush it away. But it is not, and that’s why the dentist has to scrape it off.”

Can you kill biofilm by using a disinfectant, bleach or some other type of powerful cleaning chemical?

The sticky matter not only sticks to surfaces, but it coats and surrounds the bacteria, says Montag. It’s like a protective armor that becomes very hard to penetrate. There have been tests where various cleaning products such as chlorine bleach or disinfectants at full strength (not diluted) were poured on an affected surface, and these tests found that these products had little impact on the biofilm.

If biofilm is hard to remove, how do you get rid of it?

The first option, which is actually the best option, is keeping surfaces as clean and dry as possible and making this an ongoing process. In an article for Medscape Medical News, researcher Dr. Karen Vickery from Macquarie University in Sydney, Australia, said, “Biofilms are forming on many . . . surfaces because [the surfaces] aren’t cleaned frequently enough. [If not cleaned frequently] the bacteria have a chance to attach and excrete extracellular polymeric substances, or slime, which makes them more resistant to removal and tolerant to disinfectants.”

Since bacteria typically need moisture to survive, the less moisture on surfaces, the less likely bacteria will form in large numbers. Agitation and scrubbing of potential problem areas, such as the floors in a locker room and using a sanitizer or disinfectant, can help keep biofilm from forming. Scrubbing floors can involve using a deck brush or even a low-speed floor machine. It provides the agitation necessary to loosen the bacteria and keep it from developing.

How do you get rid of biofilm if it already exists on a surface?

Depending on what type of surface the biofilm is found, the effectiveness of options can vary. According to findings published in the Journal of Hospital Infection, Vickery and her team discovered biofilms on dry hospital surfaces, and found that “microbes attached to surfaces, especially established biofilms, are less susceptible to chemical biocides, UV radiation and antibiotics” than other bacteria. However, in other cases biocides were ineffective at killing bacteria.

The study also pointed out that some surface materials are more prone to biofilm formation than others. The metal copper, for instance, is a potential candidate for antimicrobial surfaces. There is evidence that copper inactivates microbes and DNA deposited on surfaces and may reduce the transmission of pathogens in a hospital setting.

“Biocides with the highest activity against bacteria attached to surfaces, and ideally those with the ability to prevent biofilm formation and dismantle existing biofilms, should be selected,” the study states. Data on such detergents is limited, but there is some research that suggests oxidizing agents may contain more of these properties than other agents.

Meanwhile, in another study, researchers found that ozone [referring to aqueous ozone] effectively destroys biofilms, microbes and organic residue material within these films. At appropriate concentrations, ozone injected in water was found to destroy all microorganisms, viruses, oocysts and pyrogens.

Apparently, ozone worked well on its own, without additional agitation. Further, the researchers reported that ozonated water leaves no chemical residues, unlike other chemicals, and reverts back to oxygen.


Robert Kravitz is a frequent writer for the professional cleaning and building industries.

Leave a Reply

Your email address will not be published. Required fields are marked *