Antibiotics May Be Creating Bacteria Resistance, Says Study.

The addition of antibiotics to animal feed and the practice of using them to treat sick livestock is breeding new generations of bacteria resistant to those antibiotics, according to an article in the latest issue of The New England Journal of Medicine (NEJM). The finding is made even more serious as a commonly used antibiotic was thought to be one of the few antibiotics to which most bacteria have not developed a resistance. In the latest study, a group led by the Nebraska Public Health Laboratory examined the case of a 12-year-old boy infected with salmonella. The bacterium was found to be resistant to ceftriaxone and a dozen other antibiotics. Tests revealed the same resistant strain of salmonella in local cattle, the researchers said. The boy had apparently picked up salmonella from the family's cattle, which had been treated with the antibiotic during an outbreak of diarrhea, the researchers said. Precisely how the boy was infected or how many other antibiotics the cattle had been exposed to could not b e determined.

NEJM says despite extensive study of the use of antibiotics in livestock, several key questions remain. For example, how much does antibiotic use in livestock throughout the world actually contribute to antibiotic-resistant infections in humans? Does human illness associated with these resistant strains pose a greater risk of a poor clinical outcome than infection with antibiotic-susceptible organisms? The report says isolated cases provide support that the use of antibiotics in livestock leads to a large and important pool of resistant organisms.

The Animal Health Institute (AHI) disagrees with the findings. In a prepared statement, AHI said the article's conclusion that antibiotic resistant strain of salmonella evolved primarily form cattle is "speculative and is not supported by the data. No evidence is provided to show that the cattle were treated with the antibiotic in question, or for that matter, with other antibiotics." Sens. William Frist (R-Tenn.) and Edward Kennedy (D-Mass.) recently authored a bill to amend Title III of the Public Health Service Act to provide a new and critical public health infrastructure to address the issue.