Chicago,
IL- (6/3/99)- Outbreaks of foodborne and waterborne infectious disease
are on the increase around the world. To make matters worse, the percentage
of microorganisms that are resistant to antibiotics is also increasing rapidly,
and researchers are becoming increasingly concerned about crossover resistance
associated with the food we eat and the water we drink, according to reports
at the 99th General Meeting of the American Society for Microbiology
Left:
Electron Micrograph of Streptococcus, one of many bacteria that are becoming
more resistant to antibiotics
Surveillance studies conducted by US and European health authorities indicate
that the percentage of disease-causing microorganisms that are resistant to
standard antibiotic treatment has increased steadily over the past ten years.
These increases are seen in both humans and animals. The result is apparent
in US hospitals where doctors face an increasing number of cases of infectious
disease that do not respond either to vancomycin or methicillin, two potent
antibiotics that have been kept in reserve to treat infections caused by microorganisms
that are resistant to all other drugs.
Inappropriate prescribing of antibiotics has been identified as one contributor
to the problem. Resistant organisms can also develop in association with appropriate
prescribing of antibiotics if the patient does not complete the full course
of treatment. Each of those problems can be solved with better physician and
patient education.
Researchers are growing increasingly concerned about antibiotic resistance
working its way up the food chain. Antibiotics have been added to animal feed
to promote growth for decades. While the debate rages in the scientific c
community, there is a growing consensus that this practice is connected to
the rising incidence of resistant microorganisms seen in both animals and
humans.
At the end of last year, the European Community announced a ban on the use
of all antibiotics in animal feed. While the US Centers for Disease Control
(CDC) and Food and Drug Administration (FDA) have listed the problem as a
priority, neither group has called for a similar ban in the US. Rather, they
have launched a nationwide surveillance program of human and animal antibiotic
resistance. The goal of the program is to study the nature and scope of the
problem, and make decisions based on these studies.
"Antibiotic resistance associated with foodborne bacteria is now a priority
for the CDC. We anticipate that a constellation of interventions will be required
to address this problem. We are determined that all stakeholders will be involved
in the process. Ultimately, the goal will be to convert the problem from one
of urgent status to one of routine status," said the CDC's David Bell, MD,
assistant director of the National Center for Infectious Diseases.
A German study produced new evidence supporting the link between antibiotic
resistant enterococci in animals and humans. Researchers discovered an association
between the use of the antibiotic avoparin as a feed additive and the development
of transferable glycopeptide resistance in enterococcus faecium, a
human pathogen. The investigators identified resistant strains of the bacteria
from waste water treatment plants in towns that have no hospitals. They were
also able to match genetic changes seen in bacteria in animals with those
seen in the intestinal flora of people living in the same area as the animals.
"These data indicate a communication between the resistance gene pool of
enterococci in animals with that in humans," reported Wolfgang Witte, Ph.D.,
Robert Koch Institute: Wernigerude, Germany. The use of avoparcin as a feed
additive was banned in Europe 1997, and a total ban on antibiotics in animal
feed is now in place he noted.
The problem of foodborne disease can be seen in the nation's emergency rooms.
Gastrointestinal complaints, most of which are associated with foodborne pathogens,
are now the leading cause of admission to emergency rooms in the US. Of particular
concern is the high incidence of Campylobacter infection, estimated to be
present in 80% of chickens in US markets, according to Michael Osterholm,
Chief Executive Officer of the Infection Control Advisory Network. Osterholm
advocates the use of irradiation of food to reduce the likelihood of such
infections.
Waterborne outbreaks also are becoming more common and more virulent. Research
presented at the conference revealed an alarming increase in problems associated
with pathogens in the world's water supply. A US study suggests that wild
bacteria may play a role in the development of treatment resistant species.
A survey of 15 major US rivers revealed bacteria resistant to several common
antibiotics in all of the rivers. While these bacteria are not ordinarily
associated with human disease, the fact that they can transfer resistance
to other bacteria that do affect humans is cause for concern, says Dr. Ronald
Ash, professor of biology, Washburn University, Topeka, Kansas.
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