Historically, doctors
used metals to treat infections. Researchers think that this treatment method
may be worth a modern reexamination.
As an increasing
number of bacteria develop antibiotic resistance,
scientists are looking beyond this family of medications that has served us so
well up until now.
As the usefulness of
antibiotics begins to wane, there is an urgent need to develop new ways to
treat infections.
Now, researchers at
the University of Connecticut (UCONN) in Storrs say they may have found a way
forward – by looking back at how doctors treated infections before the advent
of antibiotics. Kumar Venkitanarayanan led the research team.
"In the olden days, metals were used as
antimicrobial treatments, so we decided to revisit those to see if they could
be applied to modern-day treatments."
Kumar Venkitanarayanan
Venkitanarayanan and
his team have published the encouraging results of their research in the
journal Wound Medicine.
A difficult nosocomial
infection
Infections contracted
by patients while hospitalized for other reasons are especially likely to be
antibiotic resistant.
Called
"nosocomial infections," they can be very hard to cure and can be
fatal. Among the most common nosocomial bacteria is Acinetobacter
baumannii (A. baumannii).
According to
Venkitanarayanan, "A. baumannii is primarily a nosocomial pathogen
impacting those especially with compromised immune systems, the very young, the
very old, burn victims, and is also reported in the wounds of combat
soldiers."
A.
baumannii is
adept at outsmarting antibiotics, with an array of mechanisms for evading
successful treatment.
Among these is its
ability to form self-protective biofilms that facilitate travel to the lungs —
sometimes causing pneumonia — and to the
urinary tract. In biofilm form, it is also easier for the bacteria to spread to
other patients.
Selenium
After assessing a
variety of metals and metalloids that doctors historically used to treat
infections, the researchers settled on a metalloid, the essential mineral selenium (Se), as a
promising candidate for treating A. baumannii.
Antimicrobial selenium
is a recognized dietary antioxidant, and the Food and
Drug Administration (FDA) recommend it for daily intake.
Other researchers have
also found it to be a promising counteragent to pathogens such as Staphylococcus aureus (S. aureus)Trusted
Source. Selenium is also an essential micronutrient that helps the
immune system function and aids nucleic acid synthesis.
Sneaking up on A.
baumannii
Since A.
baumannii is
such an adaptable opponent, Venkitanarayanan and his colleagues adopted a
strategy of disarming the bacteria rather than staging a full-on assault that
would threaten its survival and provoke its defense mechanism.
The
researchers began by determining the minimum amount of selenium required to
inhibit the bacteria's virulence.
To observe selenium's
efficacy with A. baumannii, the researchers constructed a model matrix
that simulated an infected wound environment containing cultured cells and
wound fluids.
They infected areas of
their "wound" with A. baumannii and selenium
sufficient to inhibit virulence. They infected other samples with A.
baumannii alone.
The researchers
examined the samples under scanning electron microscopes. They also performed
DNA analysis to determine if the selenium produced any genetic changes in the
bacteria.
In the selenium
samples, the biofilms produced by A. baumannii were severely
degraded, diffuse, and structurally unsound.
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