Cingles Info

Health & Science: Study finds food pathogens in ready-to-eat shrimp
Copyright © 2002
Scripps Howard News Service
By LANCE GAY, Scripps Howard News Service
WASHINGTON (August 9, 2002 11:09 p.m. EDT) - A shrimp cocktail is a culinary
delight, but scientists warn that cooked and ready-to-eat shrimp bought at
supermarkets may still harbor dangerous food pathogens.
Douglas Marshall, a professor of food science at Mississippi State
University, said Thursday he was surprised that he could isolate so many
pathogens on a popular ready-to-eat product. The pathogens should have been
killed when the shrimp were processed as ready-to-eat food, he said.
Marshall speculated that the problem could be caused by inadequate cooking
of shrimp at plants, poor sanitation, contamination by workers or poor water
quality in Third World countries where some of the products were processed.
Some of the pathogens he found, he explained, are not normally found in
seafood, but are commonly found carried by humans or animals.
"We found several pathogen strains we didn't expect to find, and that's
quite troubling," Marshall said. "We got a whole host of critters that from
an innocent perspective we didn't anticipate."
The study results were presented in May at a conference of the American
Society for Microbiology in Salt Lake City.
The Institute of Food Technologists earlier this year warned that
supermarket trends towards ready-to-eat products could lead to outbreaks of
food-borne diseases. Some scientists recommend that, as a precaution,
prepared foods be re-cooked to kill any pathogens that might have developed.
Marshall and graduate student Gianna Duran launched their study to see if
shrimp might have antibiotic-resistant bacteria. They purchased 13 packages
of ready-to-eat shrimp from different manufacturers at local grocery stores.
Some were refrigerated products, and others frozen. The frozen shrimp were
then thawed for the study.
The scientists concluded that 42 percent of the bacteria cultured from the
shrimp were drug-resistant. Marshall said fish and shrimp farms use drugs to
treat diseases in their stock, and that it is not surprising there should be
drug-resistant strains in the shrimp sold at supermarkets.
But the study also found pathogens that should have been killed in the
preparation process, including a waterborne agent called vibrio vulnificus.
Cases of diarrhea and even death have been linked to raw oysters and clams
tainted with the pathogen.
Other pathogens, like E. coli, staphylococcus and shigella, were also found
in the shrimp, although they are carried in the intestines of warm-blooded
animals. The study said that this suggests fecal contamination of shrimp,
probably after cooking by workers using unsanitary practices.
Marshall suggested that people with compromised immune systems should
re-heat prepared foods before consuming them.