• Ultrashort-pulse lasers kill bacterial s

    From ScienceDaily@1337:3/111 to All on Tue Nov 23 21:30:38 2021
    Ultrashort-pulse lasers kill bacterial superbugs, spores
    Technique likely safe for human cells; has potential for sterilizing
    wounds, blood products

    Date:
    November 23, 2021
    Source:
    Washington University School of Medicine
    Summary:
    Researchers at Washington University School of Medicine in St. Louis
    have found that multidrug-resistant bacteria and bacterial spores
    can be killed by ultrashort-pulse lasers. The findings could lead
    to new ways to sterilize wounds and blood products without damaging
    human cells.



    FULL STORY ========================================================================== Life-threatening bacteria are becoming ever more resistant to antibiotics, making the search for alternatives to antibiotics an increasingly urgent challenge. For certain applications, one alternative may be a special
    type of laser.


    ========================================================================== Researchers at Washington University School of Medicine in St. Louis
    have found that lasers that emit ultrashort pulses of light can kill multidrug-resistant bacteria and hardy bacterial spores. The findings, available online in the Journal of Biophotonics,open up the possibility
    of using such lasers to destroy bacteria that are hard to kill by other
    means. The researchers previously have shown that such lasers don't
    damage human cells, making it possible to envision using the lasers to sterilize wounds or disinfect blood products.

    "The ultrashort-pulse laser technology uniquely inactivates pathogens
    while preserving human proteins and cells," said first author Shaw-Wei
    (David) Tsen, MD, PhD, an instructor of radiology at Washington
    University's Mallinckrodt Institute of Radiology (MIR). "Imagine if, prior
    to closing a surgical wound, we could scan a laser beam across the site
    and further reduce the chances of infection. I can see this technology
    being used soon to disinfect biological products in vitro, and even to
    treat bloodstream infections in the future by putting patients on dialysis
    and passing the blood through a laser treatment device." Tsen and senior author Samuel Achilefu, PhD, the Michel M. Ter-Pogossian Professor of
    Radiology and director of MIR's Biophotonics Research Center, have been exploring the germicidal properties of ultrashort-pulse lasers for years.

    They have shown that such lasers can inactivate viruses and ordinary
    bacteria without harming human cells. In the new study, conducted in collaboration with Shelley Haydel, PhD, a professor of microbiology
    at Arizona State University, they extended their exploration to antibiotic-resistant bacteria and bacterial spores.

    The researchers trained their lasers on multidrug-resistant Staphylococcus aureus (MRSA), which causes infections of the skin, lungs and other
    organs, and extended spectrum beta-lactamase-producing Escherichia
    coli(E. coli), which cause urinary tract infections, diarrhea and wound infections. Apart from their shared ability to make people miserable,
    MRSA and E. coli are very different types of bacteria, representing two
    distant branches of the bacterial kingdom.

    The researchers also looked at spores of the bacterium Bacillus
    cereus,which causes food poisoning and food spoilage. Bacillus spores
    can withstand boiling and cooking.

    In all cases, the lasers killed more than 99.9% of the target organisms, reducing their numbers by more than 1,000 times.

    Viruses and bacteria contain densely packed protein structures that
    can be excited by an ultrashort-pulse laser. The laser kills by causing
    these protein structures to vibrate until some of their molecular bonds
    break. The broken ends quickly reattach to whatever they can find, which
    in many cases is not what they had been attached to before. The result
    is a mess of incorrect linkages inside and between proteins, and that
    mess causes normal protein function in microorganisms to grind to a halt.

    "We previously published a paper in which we showed that the laser
    power matters," Tsen said. "At a certain laser power, we're inactivating viruses. As you increase the power, you start inactivating bacteria. But
    it takes even higher power than that, and we're talking orders of
    magnitude, to start killing human cells. So there is a therapeutic window
    where we can tune the laser parameters such that we can kill pathogens
    without affecting the human cells." Heat, radiation and chemicals such
    as bleach are effective at sterilizing objects, but most are too damaging
    to be used on people or biological products.

    By inactivating all kinds of bacteria and viruses without damaging cells, ultrashort-pulse lasers could provide a new approach to making blood
    products and other biological products safer.

    "Anything derived from human or animal sources could be contaminated
    with pathogens," Tsen said. "We screen all blood products before
    transfusing them to patients. The problem is that we have to know
    what we're screening for. If a new blood-borne virus emerges, like
    HIV did in the '70s and '80s, it could get into the blood supply
    before we know it. Ultrashort-pulse lasers could be a way to make sure
    that our blood supply is clear of pathogens both known and unknown." ========================================================================== Story Source: Materials provided by
    Washington_University_School_of_Medicine. Original written by Tamara
    Bhandari. Note: Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Shaw‐Wei D. Tsen, John Popovich, Megan Hodges, Shelley
    E. Haydel,
    Kong‐Thon Tsen, Gail Sudlow, Elizabeth A. Mueller, Petra Anne
    Levin, Samuel Achilefu. Inactivation of multidrug‐resistant
    bacteria and bacterial spores and generation of high‐potency
    bacterial vaccines using ultrashort pulsed lasers. Journal of
    Biophotonics, 2021; DOI: 10.1002/jbio.202100207 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2021/11/211123162812.htm

    --- up 1 week, 5 days, 2 hours, 55 minutes
    * Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)