New Technique Cuts Salmonella Risk in Chicken

Preempt – a mixture of beneficial microbes that occur naturally...

Star Tribune - Friday, March 20, 1998


New York Times

A new technique Significantly reduces salmonella in chickens by providing protection that before factory farming, was naturally transferred from a mother hen to her chicks, scientists announced Thursday.

The product, called CF-3 or Preempt, a mixture of beneficial microbes that occur naturally in chicken, was approved last week by the Food and Drug Administration. "This is a major milestone for food safety," Agriculture Secretary Dan Glickman said in a National Press Club speech:

Officials estimated, the treatment would add 2 cents a pound to the retail price of chicken.

If the technique proves successful, it could also reduce the use of antibiotics in chicken, a practice that scientists say has contributed to an increase in drug-resistant bacteria.

Critics of the poultry industry were unusually optimistic about Preempt because it is one of the few tools at the farm level that reduces disease causing bacteria. But Preempt will not completely eliminate salmonella, which means that there will still be opportunities for reinfection at lower levels.

"Any level of salmonella on a bird is a problem," said Caroline Smith de Waal, director of food safety for the Center for Science in the Public Interest, a Washington based consumer advocacy group. "But if we can get numbers lower and lower, eventually more birds will be coming out of the processing plant salmonella free. The hurdle will be getting the industry to use it."

Salmonella is one of the leading causes of food-borne illness and about 20 percent of chickens are infected with it. Incidents of food-borne illnesses are difficult to track and often go unreported, but public health officials estimate that there are between 800,000 and 4 million cases of salmonellosis a year in the United States and 960 to 1,920 deaths.

Preempt also may prove beneficial in reducing or eliminating other disease causing bacteria. There is preliminary evidence that Preempt helps protect chickens against campylobacter, which is far more prevalent in chickens than salmonella and is responsible for many more illnesses.

Preempt, developed by Agriculture Department scientists and MS BioScience, a division of Milk Specialties Co. of Dundee, Ill., involves spraying newly hatched chicks with a solution that contains 29 beneficial bacteria. The birds peck their wet feathers and ingest the bacteria, which begin to grow inside the chicks' intestines. Any salmonella ingested later cannot compete the "good bacteria." and passes harmlessly through the intestines.

"What we are doing essentially is replacing the mother hen," said Dr. John DeLoach, one of the developers of Preempt and now general manager of MS BioScience. Before there were factory farms, a hen passed her resistance to salmonella to her chicks through her fecal droppings. In factory farming, the breeder hens do not stay with the chicks.

Michael Osterholm, the state epidemiologist for the Minnesota Health Department, and a proponent of irradiation, a controversial technique to eliminate disease-causing bacteria from food, is less sanguine than others about the value of the process.

"One of the major sources of salmonella contamination is in the processing plants, like the chill baths, which one processor called bacterial soup, so even if there is a lesser amount of salmonella going in there is no reason to believe there will be a lesser amount coming out."

In tests involving 80,000 chickens, the Preempt spray reduced salmonella from about 7 percent in untreated chickens to 0 percent in the intestines of the treated chickens. But salmonella was still detected in the chicken houses. And there have been no studies of salmonella levels in chickens treated with Preempt after they have been processed.

Keith Rinehart, the vice president for technical services at Perdue Farms Inc., said that the company had tried similar products in the past but that they had not proven useful in reducing salmonella levels. "The ones we've looked at didn't make that much difference by the time the chickens were ready to be processed. We are hopeful that this one is more effective. But it is definitely not a panacea because it will not take salmonella down to zero."

Dr. Donald Corrier, a veterinary pathologist for the Department of Agriculture and the project leader for Preempt, cautions that even though the product can reduce contamination "to produce a cleaner chicken there is a need for an integrated program that carries all the way through the process from farm to store. For Preempt to be beneficial requires cooperation in all parts of the industry." Use of Preempt would require farmers to change their use of antibiotics. Now, many chickens are given antibiotics when they are born to protect against disease and to accelerate growth. The antibiotics, however, kill the beneficial bacteria in the Preempt spray.

Tyson Foods, which cooperated with the field tests for Preempt, issued a statement saying that it hoped "to be able to help demonstrate its effectiveness on a large scale once it becomes available commercially." Preempt is expected to be on sale in May. The company added that it could "foresee the possibility that the use of products such as Preempt might provide the benefit of even further reducing the need for therapeutic antibiotic use."

The agriculture secretary described the introduction of Preempt as an encouraging breakthrough. "This is just one piece of a larger puzzle but it is an important step," said Glickman "It does show that research efforts pay off in terms of reducing the threat to human health."

Carol Foreman, an assistant secretary of agriculture in the Carter administration and a frequent critic of both the poultry industry and the Agriculture Department, says Preempt is "a step forward." But she added that consumers will still have to take precautions with poultry.


Deadly E. coli strain is recent evolution

UW-Madison experts work to analyze lethal bacteria's extraordinary hardiness

Milwaukee Journal Sentinel — July 31, 2000

By Jack Norman
of the Journal Sentinel staff


The 20th century added some newcomers to the grisly list of human killers, things like atomic radiation, AIDS and automobiles.

Add E. coli O157:H7 to the list.

The bacterium – responsible for the deadly outbreak of disease that authorities have linked to a Sizzler restaurant in Milwaukee – evolved into a distinct organism only, in the past century, said Charles Kaspar, a microbiologist at the University of Wisconsin-Madison who is an expert on E. coli.

And it wasn't until 1982 that E. coli O157:H7 was first documented in a case of human illness said Kaspar, a member of the 'university's Department of Food Microbiology and Toxicology. "It's not like salmonellas and others that we've known about for centuries."

The recent awareness of the threat helps explain why health professionals are so much, at a loss when it comes to dealing with E. coli outbreaks.

And the organism's extraordinary hardiness makes it especially difficult to deal with.

For example, its ability to tolerate highly acidic environments means it's not killed off when it enters a human stomach, which is full of gastric acids.

"It takes only 10 to 100 cells to infect somebody because they can get by that gastric barrier," said, Kaspar, whose work earned him this year's "Pound Research Award" from the university's "College of Agricultural and Life Sciences".

And that small level required to infect humans also means that even meat plants with very high standards can let E. coli O157:H7 through, he added.

All this makes research into the bacterium one of the cutting-edge areas of food microbiology UW Madison, with a number of scientists examining E. coli, is a world center of research in the deadly bacteria.

"Most E. coli are harmless. But about 30% are pathogenic to humans and animals," said Kaspar. "And it's those few bad cousins that really turned food safety on its head in the 1990s."

E. coli O157:H7 is the strain responsible for almost all the cases of Deadly E. coli infection in the United States, Kaspar said.

And the relative newness of the bacterium raises all sorts of research questions about its emergence, he added. "Was it because of farming practices? Because of ways we feed animals? Ways of processing or slaughtering animals?"

E. coli O157:H7 is commonly associated with ground beef, and most research has focused on its presence in cattle.

But it is present in many other animals, as well as vegetables, Kaspar said.

It has been documented in birds, raccoons and deer, as well as apple cider, sprouts and lettuce. It can be found in water, including swimming pools.

There's even a documented case of someone getting the infection from eating caribou.

Kaspar's research is focused on two issues: How does it get into and remain on a farm? Why is it so resistant to acid?

UW-Madison geneticists have recently completed sequencing the E. coli O157:H7 gene, mapping the organism's genetic code, which will help in understanding how the bacteria cause such havoc in some people, especially children and elderly people.

"I'm looking at the genes that control its acid resistance," Kaspar said.

Because the bacteria are found in the digestive system of animals such as cattle, how do they get into the meat we eat?

It's the processing that's the likely culprit, Kaspar answered. During slaughter, or during the skinning process, small pieces of intestine, may make contact with the muscles that eventually will become food for humans.

E. coli that gets onto hunks of beef can be washed off during preparation, but if the meat is ground, E. coli saturates the product, making it impossible to simply wash away.

So what can be done to prevent its spread to humans?

E. coli O157:H7 doesn't make cattle sick, so there's no way to detect infected animals.

But the organism can be killed by irradiating the meat, Kaspar said. Consumers, though, have not accepted that as a technique, he added.

"Short of irradiation, we need an across-the-board strategy, from farm to fork," he continued. "Good practices on the farm, at the processing and feed lots, when it's, cooked."

But that doesn't help eliminate E. coli O157:H7 in vegetables or water. And because it's not visible, simple inspection doesn't work either.

People need to make sure their meat is thoroughly cooked, their milk and juice pasteurized, their fruits and vegetables well-washed.

More than 100 people die each year from the infection in the U.S., and more than 10,000 are infected.

"We're gaining ground in understanding," the biologist said. "We just hope some of what happens in our laboratory can help."


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