Nanosilver no `silver bullet' in long-term treatment of infections
A popular treatment for microbial infections may lose its effectiveness
when used long-term

Date:
October 12, 2021
Source:
University of Technology Sydney
Summary:
New research has found that pathogens that form biofilms can
evolve to survive nanosilver treatment. The study is the first to
demonstrate that long-term nanosilver treatment can increase the
risk of recurrent infections.



FULL STORY ==========================================================================
New research from the University of Technology Sydney (UTS) has found
that pathogens that form biofilms can evolve to survive nanosilver
treatment. The study is the first to demonstrate that long-term nanosilver treatment can increase the risk of recurrent infections.


==========================================================================
The research is published in the Journal of Nanobiotechnology.

Nanosilver is a potent antimicrobial that is currently used in medical
devices such as internal catheters, as well as wound dressings, in
particular for burn wounds, to fight or prevent infections. It is also
one of the most commercialised antimicrobial nanoparticles, and has
been incorporated into consumer products from personal care products,
such as soaps and toothpaste, to washing machines and fridges, even
children's products, such as in kids socks to prevent odour.

Researchers at UTS's iThree Institute studied nanosilver adaptation
phenomena in the bacterium Pseudomonas aeruginosa, in its biofilm
form of growth, and observed a novel adaptation mechanism not seen
in previous planktonic growth studies. Following prolonged treatment, nanosilver killed 99.99% of the bacterial population with only 0.01%
cells surviving for longer. This minute fraction of 'persisters' resumed
normal growth upon discontinuation of the nanoparticle treatment.

"Understanding how pathogens develop adaptation mechanisms to
nanoparticles is key in our effort to overcome the phenomena, including
in biofilms as the major form of growth of pathogenic bacteria. This
is to protect the efficacy of important alternative antimicrobials,
like nanosilver, in this era of increasing antibiotic resistance,"
said lead author Dr Cindy Gunawan.

The study first author, Dr Riti Mann, said the research findings will
also help develop strategies on the better management of nanoparticle use
as antimicrobials, in particular those that involving long-term exposures.

"Based on this study, we recommend monitoring patients not only during,
but also after prolonged use of nanoparticle treatment for safeguarding
against recurrent infections.

"The scientific evidence that bacteria can adapt to nanoparticles means
we need effective regulation of the use of nanoparticles, with clear
risks versus benefits assessment and clear antimicrobial targets. With
limited development of new effective antibiotics over the past decades,
we need to preserve the efficacy of the alternative antimicrobials to
fight untreatable infections, saving lives and billions of dollars in healthcare," said Dr Gunawan.

The bacterium used in the study, Pseudomonas aeruginosa, often attach themselves on catheter surfaces, as well as to wounds and lung linings,
growing biofilms, which can be difficult to control.

========================================================================== Story Source: Materials provided by University_of_Technology_Sydney. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Riti Mann, Amy Holmes, Oliver McNeilly, Rosalia Cavaliere,
Georgios A.

Sotiriou, Scott A. Rice, Cindy Gunawan. Evolution of biofilm-forming
pathogenic bacteria in the presence of nanoparticles and
antibiotic: adaptation phenomena and cross-resistance. Journal of
Nanobiotechnology, 2021; 19 (1) DOI: 10.1186/s12951-021-01027-8 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211012112305.htm

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