Scientist urges new tactics for fighting 'plague' of resistant bacteria

By Jim Barlow

Microbiologist Abigail Salyers says the antibiotic-resistant bacteria that
science writer Laurie Garrett discusses in her book "The Coming Plague" are
already here. In her own new book, Salyers warns that many widely held
beliefs about how to prevent an increase in antibiotic resistance may be
wrong.

She also argues that bacteria in food may be a source for the transfer of
antibiotic-resistant strains of bacteria. Her book, "Antibiotic Resistance
Transfer in the Mammalian Intestinal Tract," was published by R.G. Landes
Co. of Austin, Texas.

Salyers, a professor in the College of Medicine, calls for the creation of
a long-term strategy based on reporting and communication "to prevent any
further rise in antibiotic resistance" and to ensure that resources go into
developing vaccines to prevent infections rather than into developing new
antibiotics.

"The current 'plague' of resistant strains is taking its toll not by
causing widespread death and destruction," she writes, "but by driving up
health-care costs and diverting precious medical resources." Market forces
in the 1970s, she adds, led to a glut of antibiotics, giving rise to a
false optimism that clinicians could cure infectious diseases. Since the
1980s, increases in bacterial resistance to antibiotics have created a
situation where scientists "are only barely winning the race with bacterial
pathogens."

A lot of the blame, she said, can be placed on the overuse and misuse of
antibiotics by physicians in hospitals and nursing homes. Patients and
staff are exposed to low levels of antibiotic aerosols over long periods of
time - a condition that is the most conducive to producing resistant
bacteria.

 She also considers the possible transfer of resistance genes by
genetically engineered microorganisms, by probiotics (specially prepared
bacteria or fungi designed to protect against intestinal disease), or by
bacteria in foods such as cheese, yogurt, cured meats and some types of
pickles.

"Up to this point, the safety of bacteria used in the manufacture of foods
has been evaluated solely on whether the bacteria can cause human disease,"
she said. "Completely overlooked is the question of whether bacteria in
human foods carry antibiotic-resistance genes that can spread to bacteria
that normally reside in the intestinal tract and ultimately to bacteria
that cause diseases."

The idea may seem far-fetched, she said, but with such foods eaten daily
there are "abundant opportunities." Salyers also criticizes virtually all
published studies on antibiotic-resistant bacteria, saying they focus on
minor, easy-to-cultivate populations of intestinal bacteria and apply the
findings across the board, often to very different bacteria.

"Many clinicians believe that if they stop using a particular antibiotic,
resistance will disappear rapidly," she said. "The evidence suggests that
this will not be the case. Most people assume that antibiotics are the only
selective pressure for resistant strains, but there may be other pressures,
such as certain types of pollution. If so, this changes the way we think
about combatting antibiotic resistance."