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Growth Enhancers Under Suspicion as Cause of Salmonella Outbreak

June 05, 1986|DANIEL P. PUZO | Times Staff Writer

Beef from this state's dairy cattle is the source of one of the nation's longest-running contamination cases, according to federal and local health officials, who say a sharp increase in salmonella infections has been caused by a so-called hard-to-kill or super bacteria present in the meat.

The continuing episode began in May, 1985, and since then about 1,000 Californians have become ill from Salmonella newport , which is resistant to at least six different types of antibiotic drugs.

As many as 50% of those diagnosed as suffering from the infection have required hospitalization for symptoms that can include fever, bloody diarrhea, nausea and lethargy. The bacteria can be lethal if contracted by infants, the elderly and those with weakened immune systems such as cancer patients.

Data from the 12-month-old outbreak is still being analyzed, said Dr. Steve H. Waterman, Los Angeles County's Health Services Department's deputy chief of acute communicable diseases. However, there is a strong possibility that the source of the contamination is beef from dairy cattle fed regular doses of antibiotics as growth enhancers or for disease prevention, he said.

If this premise ultimately proves true then it would be the largest, documented incidence of human illness related to antibiotic-laced meat, according to several government officials familiar with the case.

"The information we gathered clearly indicates that the source of the increased number of resistant salmonella cases was hamburger, and the data we collected does, indeed, suggest that the source of this was basically dairy cattle," Waterman said. "We also collected data on antibiotics (administered to animals) at these dairies."

Health officials emphasized that thorough cooking would be sufficient to destroy any bacteria that may be present in the meat as long as traditional sanitary practices were followed. However, the case takes on greater significance than routine food poisoning incidents because of the link with antibiotics.

Meat industry critics and medical professionals have long opposed the practice of feeding livestock animals the same antibiotics or drugs as used to treat humans, such as penicillin, tetracycline and streptomycin. Their fear is that eventually bacteria resistant to these drugs will develop in animals. Some theorize that harmful bacteria spawned in such conditions could become indestructible and therefore incurable.

When raw or undercooked meat carrying this newly formed bacteria is consumed, the contamination will be transferred to humans. As a result, physicians would be faced with patients who do not respond to treatment from traditional drugs.

"What worries us is when a bacteria that we were previously able to treat with antibiotics (such as S. newport ) is no longer affected by (these drugs)," said Dr. Robert V. Tauxe, medical epidemiologist with the Centers for Disease Control in Atlanta. "Sometimes a doctor doesn't have time to find out which antibiotic the bacteria is resistant to . . . . You hope you pick the right one and, if not, you hope the patient survives the two or three days it takes to find one that works."

Tauxe said that new antibiotics have been developed by the pharmaceutical industry to battle such hard-to-kill bacteria. However, the treatments are expensive and can cost several thousand dollars per dose.

In Los Angeles County, where most of the S. newport cases have been reported, health officials discovered that the suspect beef, consumed primarily as hamburger, originated from dairy cattle raised in Tulare and San Bernardino counties.

When the investigation was launched last year, the bacteria was also isolated at a meat processing plant and at a supermarket meat-cutting operation, thus indicating the bacteria had traveled quickly through a number of steps in the food chain. (The identities of the ranches and one of the meat-handling facilities implicated in the investigation remain confidential as part of an agreement which led to their cooperation, according to Waterman.)

Even after isolating the S. newport bacteria at several sites, little apparently can be done to eliminate the problem. Presently, the disease is in an apparent seasonal remission, but health officials anticipate an increase in the number of reported illnesses during the hot summer months of August and September when conditions for bacterial growth become ideal.

"We are still finding cases of S. newport ," Waterman said. "It appears that this strain has become endemic (native) to California . . . . And there's not a lot you can do about it other than changing the whole system of food production. It's a complex problem."

Waterman said dairy cows that have been removed from milk production and slaughtered for meat remain a major vehicle for the bacteria. The threat is compounded because once humans come in contact with raw or improperly cooked foods bearing S. newport they can also spread the disease to others.

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