BIOFILMS
- transcript of radio report aired on WSKG Radio Thursday, 11/15/2007
We've
all heard of bacteria, single-cell micro-organisms that are found
just about everywhere on earth and play a number of roles, both
good and bad. But few of us have heard of biofilms, and just
like regular bacteria, biofilms are everywhere.
"Wherever you see slime in the movies dripping from the walls or in the
shower dripping from your curtain - that's a biofilm."
That's Dr. David Davies, a microbiologist at Binghamton University. He studies
these slimy colonies of bacteria known as biofilms. But, what exactly are biofilms?
Biofilms are colonies of bacteria that attach to a surface and then excrete
a protective and adhesive matrix that allows them to stay put. You've probably
encountered them hundreds of times in your life. Those slippery, slime-covered
rocks on the bottom of a stream-bed or the film that forms on standing water.
The plaque that forms on your teeth. Those are all biofilms. Just like planktonic
-or free-floating bacteria - biofilms have their good side and their bad side.
It's the bad side of these biofilm colonies that Dr. Davies is concerned with,
namely infections.
"Biofilms cause infections that can be problems. Inner ear infections or
bladder infections, prostate infection, etc. Acne is a biofilm infection.
There are a number of instances of biofilm infections, but all of them share
the commonality
that they don't respond well to treatment with antibiotics. Generally it's
considered that a biofilm infection requires a 100 to1000 times greater concentration
of
antibiotics to treat compared to a systemic planktonic infection. Biofilms
do not respond well to therapy. So, typically a biofilm infection either has
to
resolve itself as a consequence of the immune system clearing it or it has
to be removed surgically."
The current treatment for biofilm infections, particularly skin infections
that are common in advanced-stage diabetes, range from mass doses of antibiotics
that may or may not work to wound debridement.
"Typically a dremel-type tool is taken - like a dentist's drill - and is
used on 40,000 or so rpm to scoop away, to carve out the tissue around the
infection and to get to fresh, uninfected tissue. Then, basically at that point
both patient
and physician pray that the fresh tissue will not become infected with the
organism and that the wound will resolve itself. Unfortunately, in many cases
that doesn't
occur. Particularly in advanced stages of diabetes one of the outcomes is
amputation. This is one of the things that we are really trying hard to combat."
"What we really need to do is, for instance in the case of a diabetic patient,
is to reach the tipping point where the outcome of an infection favors the
patient's survival rather than the survival of the microorganism. In doing that
- what
kinds of strategies might be available? Well, in thinking about these infections
as biofilm infections which is becoming more and more apparent, there's a
requirement for a new kind of thinking about how to reach that tipping point.
Antibiotics
just don't do it by themselves. So we have to figure out a novel strategy
to manage the bacteria so that either antibiotic treatment or the immune system
or both in combination can tip the balance in favor of the patient's recovery."
Scientists have been searching for years for a way to combat these infectious
biofilm colonies. The slime that surrounds the biofilms protects them, preventing
both the body's own immune system and antibiotics from coming into contact
with the bacteria that make up the colonies. But recent research by Dr. Davies
may change that. He's discovered a molecule that, when introduced to these
biofilm colonies, provokes certain genetic and physiological changes in the
bacteria which causes them to disperse and return to their ndividual state
where the bacteria is much more susceptible to treatment.
" What we've done is look at the behavior of biofilms as they develop in
nature and noticed that one of the common features of all biofilms is that
as they get older the bacteria from these dense cell clusters get up and disperse.
They leave the biofilm as it becomes overcrowded. It turns out that they
leave
in response to signals that are produced by the bacteria in the biofilms.
These signals build up as the cell density in the biofilm gets higher and higher.
So
it makes sense for a bacterium to leave because as the biofilm becomes more
and more dense it becomes less probable that a bacterium in the center of a cell
cluster will survive, lacking food and suffering from an accumulation of
waste
products. So here we are looking at a natural process thinking to ourselves
- how can we subvert this process or take advantage of this process and use it
to help tip the balance in an infection? We spent a long time in trying to
recover
and then identify and characterize this agent that is responsible for inducing
discursion in bacteria. Over the past year we actually completed our work
on the molecular characterization of this compound."
The molecule that Dr. Davies has isolated has been tested against a number
of biofilm infections and has proven to be effective in dispersing biofilms
containing the bacteria that cause strep, E. coli, and staph infections.
"We now know that we have a chemical that we can add to essentially any
biofilm. It works not just on the organism we isolated it from, but all bacteria
we've tested it against. It induces these bacteria, regardless of their stage
of biofilm development, to disperse from the biofilms. So the idea is that
we could take this chemical and then apply it to an infection and induce the
bacteria
to transition from a biofilm mode of growth to a planktonic mode of growth.
These planktonic bacteria are fairly easily taken care of by antibiotics and
or the
immune system."
There are many possible medical applications for this new method of dispersing
biofilm colonies, but one that Dr. Davies is particularly interested in is
the treatment of non-healing wounds.
"Non-healing wounds might not be life-threatening to a patient in many cases,
but what they do to the quality of life is profound. People losing mobility,
being unable to or embarrassed to leave their homes, unable to go out and
go on a hike, a walk, a bike ride really enjoy themselves because they are bedridden
or restricted to a wheelchair. There's no reason an 80-year-old person with
diabetes
shouldn't be out playing soccer. This is what we should be working on and
this is what we are working on. We want to be able to go in and instead of practicing
wound debridement, we want to go in and treat these non-healing wound infections
infected with biofilms, successfully have them heal and have these people
get
up and walk again. Don't amputate their feet, heal them so that they can
walk around and have a good quality of life."
This is part two of a series looking at genetic science and research in our
region. The series will continue on November 29 with a look at the adaptive
evolution of tree swallows and how that species is dealing with climate change.
This project is made possible with support from the DNA Files, a project of
Sound Vision Productions. For WSKG, I'm Crystal Sarakas.
WSKG's
DNA Files Homepage
