Janice Zoeller, Medical Tribune News Service
A program that monitors developing resistance to antibiotic
treatment reports that many commonly prescribed medications for
respiratory tract infections are losing their effectiveness.
The SENTRY Antimicrobial Surveillance Program was started in
1997 to provide better monitoring and more easily allow for
comparisons on resistance trends among different countries.
Antibiotic resistance to pneumococcus, a common cause of
respiratory tract infections, has jumped from 4 percent to nearly
40 percent in less than 20 years, said Dr. Ronald Jones, who is
lead investigator of the SENTRY program and director of
anti-infectives research at the University of Iowa College of
Medicine, Iowa City. Jones is urging patients as well as doctors to
be more judicious in their use of antibiotics. Too often, he said,
patients insist on antibiotics for a viral infection, for which
they are not effective, and doctors give in.
Some 65 percent of complaints in a doctor's office are related
to the respiratory tract, accounting for 140 million visits a year,
said Jones. This is the key area where resistance is emerging.
Doctors prescribe 50 percent of antibiotics for conditions they do
not affect, including viruses and allergies, said Jones.
Jones called for a three-pronged approach that combines
surveillance, education and new research.
There has been a decrease in the efficacy of the drugs used most
often, said Jones. Physicians need to move away from using older
drugs, he advised. With amoxicillin, there's a 20 percent chance of
resistance developing leading to ``re-entry into the medical care
system,'' said Jones. ``If it's a managed care system, that can be
a disaster.''
Jones noted that 11 years ago, ciprofloxacin treated most major
pathogens. Now more than 10 percent of organisms are resistant.
Jones said the newer fluoroquinolone class of antibiotics don't
promote mutations, so resistance won't develop as quickly. However,
he also noted that some new potent antibiotics have been associated
with liver toxicity.
In comparing resistance rates across borders, Jones noted that
in countries in Latin America where antibiotics are available over
the counter, rates of resistance are much higher. SENTRY has
documented, for example, the increasing incidence of
penicillin-resistant S. pneumoniae. World-wide rates of decreased
penicillin susceptibility are 34.7 percent in the U.S. and 60
percent in Mexico.
``We also need more research to seek new targets for
pharmaceutical therapy,'' said Jones. SENTRY is funded mainly
through a grant from Bristol-Myers Squibb.
