In a study published online Wednesday in the Journal of Infectious Diseases, an international team of researchers led by France’s Pasteur Institute describes the emergence of a multidrug-resistant strain of Salmonella, this one a variant of S. Kentucky.
The new strain is highly resistant to several antimicrobials, notably ciprofloxacin, the main antibiotic used to treat severe cases of Salmonella poisoning. Ciprofloxacin is part of the fluoroquinolone class of antibiotics, the report explains.
The scientists say the highly resistant Salmonella Kentucky, which likely emerged in Africa, infected 489 people in France, England, Wales and Denmark between 2000 and 2008, and has turned up in imported spices in North America.
While S. Kentucky is the most common Salmonella serotype found in U.S. poultry, it has caused few illnesses, the report notes. But the scientists theorize that widespread use of fluoroquinolones in Nigeria and Morocco may have helped this variant develop drug resistance. Chickens and turkeys may be carriers.
In a news release, study co-leader Simon Le Hello said, “We hope 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 multi-drug resistant strain of salmonella, Typhimurium DT104, starting in the 1990s.”
In the U.S., the Center for Science in the Public Interest has petitioned the U.S. Department of Agriculture to declare four antibiotic-resistant strains of Salmonella — Typhimurium, Newport, Hadar and Heidelberg — as adulterants in ground meat and poultry. Classifying these resistant strains of Salmonella as adulterants would require testing and controls for the pathogens before they reach consumers and make people ill, CSPI says.
Heidelberg is the antibiotic-resistant Salmonella strain found in ground turkey that has been affecting people in the U.S. since March, killing one person and sickening at least 76 others. For every lab-confirmed case of Salmonella infection, the Centers for Disease Control and Prevention (CDC) estimates there are at least 30 unreported illnesses, so this current outbreak — now linked to Cargill ground turkey brands — could be responsible for more than 2,000 infections. Nearly 40 percent of the case patients have been hospitalized.
According to the CDC, outbreaks caused by antimicrobial-resistant Salmonella have been associated with an increased rate of hospitalization and the rate of death was significantly greater in outbreaks caused by resistant strains.