New Drug-Resistant Salmonella Emerging

A multidrug-resistant strain of salmonella is emerging, a new study from French researchers finds.

The strain, known as S. Kentucky, is resistant to the antibiotic ciprofloxacin, a common treatment for severe salmonella infections .

Between 2000 and 2008, the researchers identified 489 infected patients in France, England and Wales and Denmark. Chickens and turkeys are thought to be major carriers of the microbe.

While the researchers did not identify cases of ciprofloxacin-resistant S. Kentucky in the United States, isolates of this bug have been found on spices in the U.S. imported from Africa, said Craig Hedberg, from the University of Minnesota School of Public Health, writing in an editorial accompanying the study."Contaminated food ingredients could result in contamination of animal feed as well as human food. This could serve as a portal of entry into our production agriculture systems," Hedberg said.

However, its arrival is not inevitable. "If the industry and state and federal regulatory officials are looking for them, it may be possible to keep them from becoming established in our poultry flocks," Hedberg told MyHealthNewsDaily.

Public health problem

The first infections were acquired mainly in Egypt between 2002 and 2005, but since 2006 the infections have also occurred in various parts of Africa and the Middle East, the researchers said. Most of the cases in Europe have occurred in people traveling to these parts of the world.

However, about 10 percent of infected people did not report international travel, suggesting infections may have also occurred in through consumption of contaminated imported foods, the researchers said.

Salmonella infection represents a major public health problem worldwide. An estimated 1.7 million infections occur in North America each year.

In the United States, salmonella infections are on the rise. In Europe, 1.6 million cases were reported between 1999 and 2008.

Although most salmonella infections produce only mild stomach problemsthe elderly and those with impaired immune systems are especially at risk for the illness, which can be life-threatening. These serious cases are typically treated with antibiotics called fluoroquinolones, such as ciprofloxacin.

Dr. François-Xavier Weill, of the Pasteur Institute in France, and colleagues studied information from national surveillance systems in France, England and Wales, Denmark and the United States.

Multidrug-resistant S. Kentucky was isolated from chickens and turkeys from Ethiopia, Morocco and Nigeria, suggesting that poultry is an important agent for infection. The common use of certain antibiotics in chickens and turkeys in these countries may have contributed to the rapid spread.

Although the name of a bacterial strain typically refers to the place where the strain was first characterized, this does not mean that all S. Kentucky isolates are from Kentucky, Hedberg said. In this case, the resistance of this strain to ciprofloxacin appears to have arisen in Northern Africa.

International collaboration

This study highlights the importance of public health surveillance in a global food system, the researchers say. "We hope that this publication might stir awareness among national and international health, food, and agricultural authorities so that they take the necessary measures to control and stop the dissemination of this strain before it spreads globally, as did another multidrug-resistant strain of salmonella, Typhimurium DT104, starting in the 1990s," study researcher Simon Le Hello, also of the Pasteur Institute, said.

Hedberg said the ability to integrate public health surveillance is limited by differences in national public health surveillance systems. In the new study, the percentage of salmonella samples submitted from local laboratories to national health reference laboratories ranged from 65 percent in France to 99 percent in Denmark.

"Given the medical costs and public health impact associated with the spread of multidrug-resistant organisms," Hedberg said, "the potential benefits of such a system should far outweigh its costs."

The study and editorial are published online Aug. 2 in the The Journal of Infectious Diseases.

Pass it on: A multidrug-resistant strain of Salmonella is emerging in Africa and the Middle East, with cases being reported in Europe.

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Rachael Rettner

Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.