A new class of antibiotics, the ketolides, is on the horizon for
pneumonia and other similar conditions. The new drugs offer an
alternative to standard antibiotics and another weapon in the arsenal against infectious agents that are becoming increasingly resistant to known pharmaceuticals.
Medicines called macrolides are a standard
treatment for many bacterial infections that
cause respiratory diseases. They include such
antibiotic warhorses as erythromycin. However,
infectious agents such as streptococcus and staphylococcus are growing resistant to marcolides and the primary backup, quinolones.
Ketolides are derived from the macrolides,
but they are chemically different, so they will kill
bacteria that are resistant to macrolides.
Reports on two varieties of ketolides were
presented in Toronto on Wednesday at an
infectious diseases meeting sponsored by the
American Society for Microbiology.
Aventis Pharmaceuticals filed with the U.S. Food
and Drug Administration in March for permission
to sell its new ketolide, called Ketek or
telithromycin. A similar drug made by Abbott
Pharmaceuticals, code named ABT-773, is also in
early-stage human testing.
Researchers presented 10 separate Ketek
studies at the conference involving nearly 2,500
patients. They were intended to show that
once-a-day Ketek is equivalent to other
standard antibiotics for treating a variety of
bacterial diseases, including pneumonia,
bronchitis, sinus infections and sore throats.
Macrolides work by halting bacteria's ability
to make new proteins, though some resistant strains can pump a macrolide out of its cell membrane before the macrolide can work. Because the ketolides are chemically different, the resistant bacteria do not spit them
out this way.
Ketek is given for five
days, which is shorter than most antibiotics,
so bacteria may be less able to develop resistance to this new ketolide.