Chlorhexidine linked to Antibiotic resistance??????
"A
household mouthwash may be creating superbugs," the Daily Mail
reports.
A laboratory study found the ingredient
chlorhexidine, used in a wide range of antiseptic products, increased bacterial
resistance to the antibiotic colistin. Despite the headline to the contrary,
researchers did not specifically test mouthwash or any other household
products.
Colistin is what is known as an "antibiotic of last
resort" and is used to treat Klebsiella pneumoniae bacterium that has evolved resistance to
other more widely used antibiotics. Klebsiella pneumoniae can cause
pneumonia, meningitis and other infections.
Researchers found these bacteria became
resistant to increasing concentrations of the antiseptic chlorhexidine, which
is found in products such as mouthwash and wound dressings. The results are of
potential concern as the rate of Klebsiella
pneumoniae is increasing in UK hospitals.
But in a related press release, the study's
lead author, Dr
Mark Sutton, stressed that disinfectants containing chlorhexidine
and similar antibacterial products currently play a vital role in infection
control in both the home and in hospitals. Dr Sutton also added: "This is early research in a laboratory
setting and more work needs to be done to understand the potential implications."
Where
did the story come from?
The study was carried out by researchers from
the Technology
Development Group, Public Health England, Microbiology Services Division in the
UK.
It was funded by Public Health England, and the
authors declared no conflicts of interest. The study was published in the
peer-reviewed journal, Antimicrobial Agents and Chemotherapy. It is an open
access study, so you can read it free online.
While the Mail's overall reporting was
accurate, it does seem somewhat odd that they focused on mouthwash in general,
and specifically on the Corsodyl brand. Many other commercial products contain
chlorhexidine.
As the manufacturers of Corsodyl,
GlaxoSmithKline, point out in the Mail article: "Corsodyl mouth rinse contains a very low concentration of chlorhexidine
(0.2%) and is intended for short-term use only."
The results of the article would seem to be
more of a potential concern for health professionals responsible for infection
control in hospitals than members of the public trying to keep their teeth
clean and gums healthy.
What
kind of research was this?
This laboratory study investigated the
adaptation of the pathogen Klebsiella
pneumoniae to the antiseptic chlorhexidine, and whether this caused
cross-resistance to other antibiotics. While laboratory studies are useful ways
of seeing the biological mechanisms and how things may work in humans, their
findings cannot necessarily be extrapolated to beyond the lab. It may be that
the conditions in the laboratory do not reflect real life.
What
did the research involve?
Researchers took clinical strains of Klebsiella pneumoniae that were placed
in a concentration of the antiseptic chlorhexidine to find out if it builds up
immunity.
Adapted strains of Klebsiella pneumoniae were also added to colistin, a last-resort
antibiotic, to investigate if there was cross-resistance of Klebsiella
pneumoniae to this antibiotic.
Strains were cultured in a concentration of
chlorhexidine or colistin and put in a new concentration – double that of the
previous – every two days. This continued six times.
The researchers then measured the resistance
of these strains of Klebsiella pneumoniae
to different concentrations of chlorhexidine and colistin.
What
were the basic results?
Klebsiella
pneumoniae strains are able to adapt to increasing concentrations
of chlorhexidine. This leads to increased minimum inhibitory concentrations.
These are the lowest concentration of an
antibiotic (chlorhexidine) that will inhibit the visible growth of a
micro-organism (Klebsiella pneumoniae).
This means that lower concentrations of
chlorhexidine became less effective at inhibiting Klebsiella pneumoniae growth.
These adapted strains of Klebsiella
pneumoniae were also more resistant to the antibiotic colistin. This means the
chlorhexidine exposure had led to what is termed antibiotic cross-resistance.
In five out of six strains, the minimum
inhibitory concentration values for colistin increased from 2-4mg/L to more
than 64mg/L, meaning lower concentrations of colistin became less effective at
inhibiting Klebsiella pneumoniae.
How
did the researchers interpret the results?
The authors concluded that, "increased colistin and chlorhexidine
resistance may occur in clinical isolates without significant loss of
fitness/virulence".
They added that this "highlights the
potential challenges associated with critical infection control procedures and
the use of chlorhexidine as an antiseptic to control healthcare-associated
infections".
Conclusion
The authors show that Klebsiella pneumoniae strains are able to become more resistant to
the widely used antiseptic chlorhexidine.
They also show that in five of six strains,
adaptation to chlorhexidine also led to resistance to colistin, a last-resort
antibiotic.
There is a potential risk that colistin
resistance will emerge in Klebsiella pneumoniae
as a result of exposure to chlorhexidine, given the wide range of products sold
to the NHS that contain active concentrations of chlorhexidine.
Klebsiella
pneumoniae infections and outbreaks are becoming increasingly
common in hospitals and can cause a range of diseases, including pneumonia,
bloodstream infections, wound infections, surgical site infections, meningitis
and urinary tract infections.
While it is true that chlorhexidine is in a
range of products, including mouthwash and wound dressings, the study did not
specifically look at mouthwash or any other household products. There is no
evidence that using these products is unsafe or has caused an increase in
infections.
As lead author, Dr Mark Sutton, concluded in
a press release: "Chlorhexidine is a
common ingredient in a number of disinfectants used widely in the home and in
healthcare settings, where it is an important part of many infection control
practices. People should continue to practice good infection control, including
the use of disinfectants, in order to prevent infections in the first place. This
is early research in a laboratory setting and more work needs to be done to
understand the potential implications."
Comments
Post a Comment