Antibiotics in animals breed resistant salmonella, new evidence

One in five samples of ground meat and poultry taken from US supermarkets was contaminated with salmonella, and most samples were resistant to antibiotics, a US study reports this week. Scientists from the Department of Nutrition and Food Science, at the University of Maryland set out to identify and characterise strains of salmonella isolated from ground meats purchased in the Washington, D.C., area. Salmonella was isolated from samples of ground chicken, beef, turkey, and pork purchased at three supermarkets. The polymerase chain reaction and DNA sequencing were used to identify resistance integrons and extended spectrum -lactamase genes. Results showed that of 200 meat samples, 41 (20 percent) contained salmonella, with a total of 13 serotypes. Eighty-four percent of the isolates were resistant to at least one antibiotic, and 53 per cent were resistant to at least three antibiotics. Sixteen per cent of the isolates were resistant to ceftriaxone, the drug of choice for treating salmonellosis in children. The scientists conclude that resistant strains of salmonella are common in retail ground meats. They stress that their findings provide support for the adoption of guidelines for the prudent use of antibiotics in food animals and for a reduction in the number of pathogens present on farms and in slaughterhouses. Full findings are published in the October 18 issue of The New England Journal of Medicine.