Antibiotic Resistance Bacteria in Your Backyard
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New research carried out at Edith Cowan University (ECU) has found soils containing low levels of heavy metals are likely to contain antibiotic resistant bacteria.
The study found a link between the naturally occurring presence of heavy metals in soil and the presence of bacteria with antibiotic resistant genes.
This means that a degree of antibiotic resistance occurs naturally and without human interference.
Previously, international studies suggested increases in resistant bacteria were linked with soils that were contaminated with high levels of heavy metal.
The study, conducted by the School of Science and School of Medical and Health Sciences, took soil samples from 90 different residential properties around WA, and tested them for the presence of 12 metals.
The DNA of the bacteria found in the samples were then tested for 13 different genes that cause antibiotic resistance.
The bacteria tested were predominantly not harmful to humans, but a small number could pose a health risk, there research revealed.
Researcher Dr Annette Keonders told ECU Daily:
“Soils generally have a very rich community of bacteria which perform all sorts of different functions, the vast majority of which are not pathogenic, so they don’t cause disease.
“Some could cause disease if a person is weak, or under certain conditions, and some of them may be pathogenic.”
The study shows that antibiotic resistance in bacteria is common and not necessarily caused by human interference.
“Resistance to antibiotics in soil microbes is actually quite common,” said Dr Keonders.
“It’s a naturally occurring thing, so it’s not because of something that we’ve done. When we make bacteria that are resistant to antibiotics, we are really just tapping into a defence mechanism that already occurs naturally in bacteria.”
The study illustrates that antibiotic resistance occurs naturally in bacteria that have not come into contact with antibiotics, when the bacteria is exposed to heavy metals and an immune response is triggered.
“Heavy metals in large amounts generally are not good for our health, or any organism’s health,” she said.
“The way bacteria deal with this, is they have genes that mean they can turn on mechanisms that allow them to either export the heavy metals, so they don’t accumulate in their cells, or to somehow neutralise them in their cells.
“Coincidentally, some of these mechanisms are the same mechanisms we activate when we administer antibiotics to bacteria. It’s the same process for either making sure the antibiotics don’t come into the cell or for removing them or neutralising them.”
The study adds to a mounting body of work that allows scientists to better understand how bacteria, and their antibiotic resistant genes, function in their natural environment.
“It’s part of research that shows that these genes are naturally present in bacteria all around us. It cautions that there is this pool of naturally resistant bacteria already out there, and we need to be aware of this when we use antibiotics against diseases.
“We also need to be aware about the quality of our soils. If we have soils that are heavily contaminated with heavy metals, the number of bacteria with resistance to antibiotics would be higher already,” said Dr Keonders,
She added that the study findings are not a cause for concern.
“Nobody should freak out over this, because these bacteria, and this resistance, have been around for a long time, and we have lived quite happily with them. This isn’t a paper that says you should never touch soil!
“It just lets us know that this is a widely occurring phenomena, and when we do administer antibiotics, we often do it to a population of bacteria that has some resistance already.
“We need to be aware that they are already present because of environmental influences, and we’re working with a background amount of antibiotic resistance before we even come into the picture.”
The study, called “Relationship between antibiotic resistant genes and metals in residential soil samples from Western Australia”, can be found here: http://rdcu.be/qwwP