Biofilm: What It Is, Why We Need to Know, and How to Remove It

September 29, 2016 | cleancore | Filed Under: Aqueous Ozone information, Blog, Trade Magazine stories

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In the coming years, cleaning professionals and building managers in all types of settings may have to contend with a new—at least new to them—threat to the health of building users: biofilm.

Microbial communities, known as biofilm, were first reported on in 1684 by Antonie van Leeuwenhoek, a Dutch scientist. He found a huge accumulation of microorganisms in dental plaque, and in a report to the Royal Society of London, he said, “The number of these animalcules in . . . a man’s teeth are so many that I believe they exceed the number of men in the kingdom.”

This observation tells us a few things. First, the place where we hear the most about biofilm is, to be frank, in our mouths. The plaque on teeth is usually biofilm. However, since this report, dating back more than 500 years, we now know that biofilm can be found on a variety of surfaces—from floors to counters to sinks and even in dog food and water bowls.

And we have learned something else. The amount of germs and bacteria housed in biofilm can be huge. And if it is found, for instance, on a restroom counter, this huge microbial community does have the potential of causing serious illness.

To better understand biofilm and learn ways to eliminate it, here are some of most common questions facility managers have about biofilm…and their answers.

How do we define biofilm?

Biofilm is like a cover, a dense glue cohesive, and within it are huge numbers of pathogens, mostly bacteria. Because of this, some public health officials refer to biofilm as “bacterial cities.”

We know biofilm is found in plaque, but where else is it found?

It can be found just about anywhere, and often in dry areas of a facility, where it would not be expected. But for the most part, it does need moisture to survive. “That’s why we might find it on rocks near a waterway or in spas and Jacuzzis, where water circulates,” says Matt Montag, Distribution Sales Manager for CleanCore™, manufacturers of aqueous ozone cleaning systems for the professional cleaning industry. “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 it first forms, no, except under a microscope. However, as it grows and becomes larger, there usually is discoloration that occurs on the surface where it is attached. Often it takes on a brown, yellow or pink color, but this can vary.

Is it hard to remove?

That’s our first problem, according to Montag. “Biofilm is hard to remove…and as the individual cells of bacteria and pathogens grow, they weave and interconnect. 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’t you “kill” biofilm by using a disinfectant, bleach, or some other type of powerful cleaning chemical?

Montag says this is typically the second question building managers have. The sticky matter not only sticks to surfaces, but it coats and surrounds the bacteria. 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.

Because it is hard to remove, what are our options when dealing with biofilm?

The first option, which is actually the best option, is keeping surfaces as clean and dry as possible and making this an ongoing process. Researcher Karen Vickery, Ph.D., from Macquarie University in Sydney, Australia, says, “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.”

Also, while we mentioned it can be found on unexpected dry areas, bacteria typically need moisture to survive, so the less moisture on surfaces, the less likely bacteria will form, at least 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 means 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?

We have options, some better than others, and the effectiveness of these options can vary, for instance, depending on what kind of surface the biofilm is found. In one test reported by Dr. Vickery, in some cases, biocides, similar to a disinfectant, worked relatively well when applied to test surfaces in a hospital. However, when “isolates were grown as biofilms [in a culture], the biocides were ineffective at killing [the] bacteria.”

Another study was more upbeat. These researchers found that “ozone [referring to aqueous ozone] effectively destroys biofilms, microbes, and organic residue material within these films, [and] at appropriate concentrations, ozone injected in water destroys all microorganisms, viruses, oocysts, and pyrogens.” Apparently, the 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.” 1

Further studies have found that oxidizing agents such as sodium hypochlorite, found in some broad-range disinfectants, and hydrogen peroxide can be effective. Usually these must be used in conjunction with some form of agitation in order to work through the protective armor and sticky matter covering the bacteria and bonding it to the surface.

Finally, is biofilm viewed as a growing menace in the future?

“At this time, we view it is something facility managers must be aware of,” says Montag. “Hopefully with these common questions answered, now building managers and cleaning workers have better insight into biofilm and ways to deal with it.”

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

1 Annel K. Greene, Zeynep B. Güzel-Seydim, and Atif Can Seydim, “Chemical and Physical Properties of Ozone,” in Ozone in Food Processing, ed. Colm O’Donnell, Brijesh K. Tiwari, P. J. Cullen, and Rip G. Rice (Oxford: John Wiley & Sons, 2012), 19–31.