Drug-resistant salmonella on rise in U.S. - study
Wire Service: RTna (Reuters North America)
Date: Wed, May 6, 1998

Release at 5 p.m. EDT
By Gene Emery
BOSTON (Reuters) - The risk of being infected by drug-resistant
salmonella bacteria is increasing dramatically and the continued practice
of feeding antibiotics to livestock is exacerbating the problem,
researchers said Thursday.
Salmonella poisoning strikes up to four million Americans a year,
killing about 500. Caused by eating contaminated food, it is characterized
by sharp stomach pains, fever and diarrhea and usually lasts from two to
five days.
One strain of the salmonella bacteria, known as DT104, is quickly
becoming resistant to a wide range of antibiotics.
A study in Thursday's New England Journal of Medicine said
laboratories across the United States were finding a greatly increased
incidence of resistant bacteria when testing salmonella samples for
resistance to five common antibiotics.
The drug-resistant salmonella bacteria were found in just 0.6 percent
of samples in 1979. By 1996 the prevalence had risen to 34 percent,
researchers from the U.S. Centers for Disease Control and Prevention (CDC)
reported.
Using data from three sources, Kathleen Glynn and colleagues
discovered that "in the past five years in the United States there has been
widespread emergence of a strain" resistant to five major antibiotics.
They estimated the resistant bacteria were infecting between 68,000
and 340,000 people each year. Most would recover on their own but if
doctors needed to treat them because they got very ill, several common
antibiotics would be ineffective.
Researchers have warned for more than a decade that the practice of
speeding animal growth by adding common antibiotics to livestock food was
fostering the evolution of drug-resistant bacteria, but it remains common
today.
Already in the United Kingdom "DT104 now appears to be widely
distributed in food animals, particularly cattle, and investigations have
associated infections in humans with eating pork sausages, chicken and meat
paste, and with contact with sick animals," the CDC researchers said.
More than 16 million of the 50 million pounds of antibiotics produced
in the United States each year are combined with animal food so the animals
will grow faster.
The low levels of antibiotics give bacteria in the animals a chance to
develop resistance. And once bacteria develop a resistance to one
antibiotic, they rapidly learn to withstand the onslaught of others, said
Dr. Stuart B. Levy of Tufts University School of Medicine in an editorial
in the journal.
"The DT104 strain, whose frequency is rising in the United States, has
been plaguing animals and people in Europe for the past decade. There, the
organism has acquired resistance to seven drugs that are used to combat
it," Levy said.
Last year, an expert panel of the World Health Organization repeated
the call for a ban on the use of human antibiotics to promote the growth of
livestock. The group also called for careful use of antibiotics to stop
diseases in food animals.
"We need to minimize the environmental impact of antibiotics," Levy
said.
Doctors should stop giving them to humans who have viral infections,
for which the drugs are ineffective anyway, and their use in animals should
be limited, he said.
REUTERS

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