A targeted antibiotic that acts as a ‘Stealth bomb’ could wipe off infections caused by microbes that are resistant to most drugs according to mice studies.
Sanjeev Mariathasan and a team of scientists at
Genentec, California, have come up with this strategy of gluing an antibody
against Staphylococcus aureus to a modified version of rifampicin. This
concept is borrowed from cancer treatment, where an ‘antibody–drug conjugate’
docks onto cancer cells before deploying its cancer-killing payload. Infections
caused by methicillin-resistant Staphylococcus aureus (MRSA) are
difficult to manage with commonly used antibiotics and are responsible for
significant morbidity and mortality rates. S. aureus is difficult to
target and to eliminate once it invades the cells and that is where the
antibody-antibiotic combination drug was found to be highly effective. When
mice were infected with MRSA and treated with a control drug and with this
experimental combination drug, it was found that the experimental drug was
about a thousand times effective against MRSA.
The mechanism of action of this combination drug is
interesting that, first the antibody component docks onto the bacteria in the
mouse’s body and as the bacteria invade cells, the therapy travels along. Once
inside, the antibiotic is activated where it is required to kill the pathogen.
However, it is to be noted that the immunopathological mechanisms could be
different in human body and also that, those chronically infected with S.
aureus, would already have antibodies to it which could interfere with the
binding process. Further studies are required to evaluate if this experimental
drug would work in humans and if it works, it could open doors to newer
therapeutic avenues where large resource of antimicrobial drugs that had not
survived the pipeline could be brought back.
Image credit: National Institute of Allergy and
Infectious Diseases (NIAID)
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