Biofilm based wound care

Published on October 7, 2014   42 min
0:00
This is Dr. Randy Wolcott, and this presentation will be on biofilm-based wound care. Let's get started.
0:10
Those are our objectives, the main objective being that there's two ways by which bacteria cause infection. I do have a conflict of interest as being a part owner of PathoGenius Laboratory. It's a laboratory that uses DNA to identify microbes. And let me just brag about PathoGenius for a second. When NASA wanted to make sure there was no microbial DNA on Curiosity, they turned to our laboratory. And that's really cool, and that gives us a lot of credibility. But we started asking ourselves, why would they care if there's microbes on Curiosity? Well, then we understood that the Martians really don't like bacteria. Well, this is to point out that we're going to stick with hard science. And when I make my reaches and conjectures, I'll be sure to identify that.
1:00
The first thing we have to understand is what a biofilm is. Bill Costerton coined this term in the late '70s, when he was seeing slime on a rock in the alpine streams. This slime that's on this piece of wood is microbes. It's the self-secreted goo of the microbes. But it's also sand and grit and the wood that it's attached to. So all of that would be called biofilm in nature.
1:30
This is an overview of the life cycle of biofilm. What Peg Dirckx is illustrating here are the four basic components of biofilm, which is attachment, microcolony formation, quorum sensing to form a mature colony, and then reproduction. So individual bacteria, planktonic bacteria, find a surface, they attach. Once there's a quorum or a sufficient number of these bacteria, a structure, a three-dimensional structure, rises up off the surface and forms the channels and the architecture that we call mature biofilm. Reproductively, 70% comes off as detachment fragments, and 30% come off as seeds. So the detachment fragments have all the colony defenses of the mature biofilm. And then the seeds are the planktonic or individual free-floating bacteria that we understand as bacteria on a Petri dish.
2:28
Biofilm development in a host setting is quite different. In this series of scanning electron micrographs by Masako, we see that, at five minutes, the bacteria attach to the cover slip, then they secrete a substance which polymerizes fibrinogen into fibrin out of the surrounding plasma. This fibrin attaches the bacteria tightly to the cover slip. And by 45 minutes, that web is quite extensive. Then, at one hour, you can see that there's a fluffy substance developing around the individual bacterial cells. And that's secreted polymeric sugars, DNA, proteins from the bacteria, or all three to form the fortress or the matrix around the community. By 24 hours, the community is mature. And the startling part of this is that it's mainly comprised of host substances, such as fibrinogen, collagen, or other host proteins.
3:33
In 2008, we proposed biofilm may be a major barrier to wound healing. There was emerging understanding at the time that biofilm phenotype bacteria could form in a host setting. And there is bacteria on the surface of wounds. And if it was organized as biofilm, that would allow the bacteria to avoid host defenses. It would protect the colony members from systemic antibiotics. It would protect the colony members from topical agents, biocides or antibiotics, all the while not allowing fibroblasts or keratinocytes or other wound components to proliferate or to do the job that they need to do to close the wound.
4:20
So let's look at our hypothesis. There are microorganisms on the surface of every chronic wound. Now, those microorganisms can do one of three things. They can have a positive effect on the wound and aid in healing and be considered something like a commensal. And those bacteria just don't exist. They could be neutral, where they don't harm or hurt the wound. And that would be considered a contaminant. Well, understand that. That's a bacteria that sits there and just doesn't propagate or cause any problems. Or the bacteria on the surface of the wound could have a negative effect on the wound. And we could call that infection. Now, so many times, we hear about colonization, critical colonization. And nobody really knows what those concepts mean. But the point is, can this bacteria that we're showing here for a chronic wound, can that cause a negative effect? You can see the extracellular matrix. You can see that there's rods. You can see that there's cocci down at the bottom. And it's all done by that fibrin web that we showed earlier. And this would be considered biofilm. Can biofilm have a negative effect on the wound?
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Biofilm based wound care

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