New Drug-Resistant Strain of Salmonella Found

Two common antibiotics ineffective against it

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By
HealthDay Reporter

FRIDAY, April 16, 2004 (HealthDayNews) -- Taiwanese doctors have identified a potentially fatal strain of salmonella bacteria that is resistant to two antibiotics widely used to treat serious infections.

The appearance of the multi-resistant strain "is a serious threat to public health, and thus constant surveillance is warranted," physicians at the Chang Gung University College of Medicine report in the April 17 issue of The Lancet.

About 40,000 salmonella infections are reported in the United States each year. Most cause diarrhea and other intestinal problems that clear up in a few days without antibiotic treatment. Infections tend to be more common and more serious in underdeveloped countries because the bacteria is spread by contaminated food and water.

Most of the literally hundreds of strains of salmonella aren't particularly virulent. But the resistant bacteria detected in Taiwan belongs to a subgroup with the scientific name S. choleraesuis that can cause potentially fatal infections, the researchers said. About 600 Americans die each year from such infections.

The salmonella isolated from a 58-year-old Taiwanese man is resistant to both Cipro and Rocephin, the Taiwanese doctors report. Resistance to Cipro is common. Two years ago, the same group of researchers reported that strains of salmonella can develop resistance to Cipro in less than two years. They found that while none of the samples they tested in 2000 were resistant to Cipro, 60 percent were resistant by the third quarter of 2001.

The new study contains their first report of a strain resistant to Rocephin as well.

The antibiotics are members of different chemical families. Rocephin, whose scientific name is ceftriaxone, is a cephalosporin and Cipro is a fluoroquinolone.

"These are the two powerful modern antibiotics that are used to treat serious cases of salmonella," said Becky Goldburg, a senior scientist at Environmental Defense, a New York-based group that has crusaded against the use of certain antibiotics in animal feed due to concerns about drug-resistant germs. "When the infection is resistant to them, it is untreatable."

Because the finding is just one instance of reported multiple resistance, "it is hard to know how common it might be," Goldburg said. But the fact that Cipro-resistant salmonella quickly became common in Taiwan is not a good sign, she said.

Vulnerable groups, such as young children, very old people and persons with compromised immune systems are most likely to need antibiotic treatment for salmonellosis, Goldburg said.

"So not having antibiotics to treat them is potentially worrisome," she said.

A spokesperson for the U.S. Centers for Disease Control and Prevention said the agency could not comment on the Taiwan report because CDC scientists were not involved in the study.

More information

For more on salmonella, visit the U.S. Centers for Disease Control and Prevention and the U.S. Food and Drug Administration.

SOURCES: Becky Goldburg, Ph.D, senior scientist, Environmental Defense, New York City; April 17, 2004, The Lancet

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