Cleaning product residues may be driving antibiotic resistance
When exposed to low levels of disinfectants and antiseptics in the lab, a bacterium that sickens thousands in the U.S. every year becomes more tolerant to antibiotics
Most microbes perish when exposed to common cleaning products, but the residue from those disinfectants may be driving bacteria to become resistant to antibiotics, a lab study suggests.
Biocides, which include disinfectants and antiseptics, are chemicals that are widely used in households, hospitals and manufacturing to kill disease-causing microorganisms such as bacteria.
However, there are rising concerns that their widespread use may be spurring antibiotic resistance by pressuring bacteria to evolve in ways that make them less vulnerable to the drugs.
In the new study, published Monday (Oct. 9) in the journal Nature Microbiology, scientists focused on one species of multidrug-resistant bacteria called Acinetobacter baumannii, which sickens thousands of patients in U.S. hospitals each year.
The researchers revealed that low levels of several common biocides — for example, those that would be left over on surfaces and that are hard to remove from the environment — can push the germ to gain tolerance to antibiotics.
Specifically, A. baumannii grows resistant to antibiotics that target the inside of bacterial cells, preventing them from making new DNA or proteins.
“Our finding suggests that biocides at low concentration can compromise antibiotic potency and lead to the development of antibiotic resistance,” Liping Li, lead study author and research fellow at Macquarie University in Sydney, told Live Science in an email.
“We propose that further investigation and survey about the side effects of residual biocides in real world scenarios are necessary to warrant that we are using these precious chemicals wisely and safely,” he added.
A. baumannii normally live in soil and water. It is an opportunistic pathogen, meaning that it doesn’t usually harm healthy people but may seize the opportunity to attack those with weakened immune systems or to enter hospitalized patients’ bodies via open wounds.
A. baumannii can cause serious diseases — including pneumonia, bloodstream infections, and the nervous-system infection meningitis — and various strains have developed resistance to multiple antibiotics.
The authors of the new study introduced mutations into the genome of A. baumannii to determine which genes would help the bacteria survive when treated with 10 biocides.
By exposing the mutant bacteria to different cleaners, they identified several of these survival genes; some coded for proteins in the wall that surrounds bacterial cells, and others coded for proteins inside the cells, including proteins involved in metabolism or respiration, the process by which cells make fuel.
According to the team’s experiments, one key way these biocides kill bacteria is by disrupting the electrical activity across their cell membranes; this hampers the cells’ ability to make fuel.
But if the concentration of biocide isn’t high enough, this won’t kill the bacteria — instead, it makes it stronger, they found.
Indeed, in seven of the 10 biocides tested, low levels of the products were enough to disrupt this membrane activity but not kill the bacteria. What’s more, this low-level exposure made it so antibiotics that targeted the insides of cells couldn’t infiltrate the bacteria as easily.
Two particularly bad offenders appeared to be the biocides, chlorhexidine and benzalkonium.
Antibiotics that target the cell envelope were not affected and could still kill the microbe. The authors hypothesized that this is because the inside-targeting antibiotics were less likely to be imported, likely because this process requires energy from the cell, which would make them less potent against A. baumannii.Â
The study was conducted only in lab dishes, not in a real-world setting like a hospital. However, the authors noted that this suggests it may be time to talk about “biocide stewardship.”
So-called antibiotic stewardship is a critical effort to stop the misuse of antibiotics and thus limit the pressure that normally pushes bacteria toward resistance. The authors think biocide stewardship may also be necessary.
The “principal concern” of biocide stewardship would be to figure out how to reduce the amount of residual biocide in the environment after cleaning, to prevent bacteria from being exposed to too-low concentrations of the cleaners and thus stop them from gaining resistance, the authors wrote.
See more here livescience
Header image: andresr via Getty Images
Please Donate Below To Support Our Ongoing Work To Defend The Scientific Method
PRINCIPIA SCIENTIFIC INTERNATIONAL, legally registered in the UK as a company 
incorporated for charitable purposes. Head Office: 27 Old Gloucester Street, London WC1N 3AX.Â
Trackback from your site.
VOWG
| #
Now where did I read too clean is bad?
Reply
Whokoo
| #
Inside your immune system instruction manual.
Reply
J Cuttance
| #
During covid, a colleague and myself were supposed to wander around our plant – a huge meat processor – spraying hand rails etc with disinfectants including benzalkonium. We didn’t and, instead, found warm places to sit the winter out. This article makes me proud of my skiving and how we prevented superbugs from arising, ha!
Reply
John V
| #
Some of my family members were so spooked by Covid, they actually wiped down boxes and containers purchased from the grocery store! My God, they totally lost all common sense during the pandemic. And they both got it anyway! And then they added insult to injury by getting
Reply
John V
| #
The shot! My brother kept lecturing me on how I was going to die.
Long story short, I did get something they called Covid positive a year later, only larangytus and my wife hasn’t been sick at all. And we didn’t do a damn thing the experts said.
Reply
Jerry Krause
| #
Hi You All,
It seems we all seem to be in agreement about the topic of this article. But I ask: How many of you remember DDT and lived on a farm which had a large population of barn flies when DDT was first used to kill barn flies after it had been successfully used to kill lice during WWII without any harmful side effects upon the soldiers being deloused.
The first year DDT was used to kill barn flies it was tremendously successful. However the second year it was not. And the explanation was that there had been a minor population if flies
with a natural immunity to DDT and after the major population had been removed this minor population thrived (exploded).
But the story of DDT does not end here. Some mosquitoes are hosts to parasites which cause malaria. And the region of the Panama Channel (sp?) and human case of malaria almost shut down the construction of it. So DDT was tried to kill these mosquitoes and it has been found there seem to be no mosquitoes which are naturally immune to DDT.
However, DDT is a very stable molecule and by natural consequences moved up the food chain until it was discovered that it softened the egg shells of a certain popular bird with a quite limited population. So DDT became banned and remains banned as the cases of malaria increase. But it seems birds are more important to some than humans whom these bird lovers don’t know.
I believe Solomon taught: there is nothing new under the sun.
Have a good day.
Reply