Two Common Drugs Pose Low Risk to Humans

Elanco Animal Health contracted for an independent analysis of its two most popular animal antibiotics to dispel public concerns about their safety.

Elanco Animal Health contracted for an independent analysis of its two most popular animal antibiotics to dispel public concerns about their safety.

A comprehensive risk assessment conducted on antibiotics in food animals reveals that the risk of consumers in the U.S. acquiring foodborne bacteria from eating meat or poultry treated with either tylosin (Tylan) or tilmicosin (Pulmotil) is very low.

The chance of acquiring a resistant infection from eating pork, resulting in treatment failure, is extremely low. The risk is less than one in 53 million people/year for resistant campylobacter and less than one in 21 billion people/year for E. faecium, according to the report's findings.

“Our risk assessment scientifically addresses questions regarding the potential impact antibiotics may have on human health, and shows that current uses of tylosin and tilmicosin in food animals are safe,” observes lead author Scott Hurd, DVM, Hurd Health Consulting, Roland, IA.

“Clearly, for these two products, I think the message is clear that they are safe,” says Hurd, who conducted the trials independent of his work as an epidemiologist for USDA's National Animal Disease Center in Ames, IA.

“The numbers were strikingly low in this study. You would be 10 times more likely to die from a bee sting, and the risk of death from a bee sting in the U.S. is one in six million,” he explains.

In the independent study, a team of eight researchers reviewed the use of tylosin and tilmicosin in food production in the U.S., analyzed the risk for antibiotic resistance and determined the potential for ineffective human antibiotic treatment as a result.

Antibiotic Resistance Growing

“While antibiotic resistance in humans is growing in the U.S., the major factor affecting resistance development is human antibiotic use, not food animal use,” says study researcher Ronald Jones, MD, The Jones Group/JMI Labs, North Liberty, IA. “Surveillance data from the Antimicrobial Surveillance Program and other monitoring programs clearly shows a disconnect between antibiotic resistance patterns in humans and animals. Government authorities should continue to review global resistance patterns and use scientific methods, such as risk assessment, to make decisions,” he says.

The findings were presented recently in Chicago at the Interscience Conference on Antimicrobial Agents and Chemotherapy.

GAO Addresses Issue

The General Accounting Office (GAO) is developing a report on antimicrobial uses and potential impact on human health and foreign trade, reports the National Pork Board.

The GAO report is due out in the spring of 2004.

Antibiotic Resistance Study Underway

The U.S. Department of Agriculture has contracted with Michigan State University (MSU) to study antibiotic use in farms and its role in the increase in antibiotic-resistant bacteria that are pathogenic to humans.

“Although the use of antibiotics in livestock is at most only a minor contributor to the problem of antibiotic resistance in human disease, the livestock industry is concerned and seeks ways to reduce this minor contributor to even less of a threat,” observes MSU veterinary researcher and project leader Barbara Straw, DVM.

Straw is reviewing results of trials of three different finishing pig antibiotic feeding regimens to determine if a reduction or modification could influence the level of antibiotic resistance.

Pigs in 20 wean-to-finish barns were placed on one of five protocols from 50 lb. to market: low-level tylosin; pulse, high-dose tylosin; low-level, continuous chlortetracycline; pulse, high-dose chlortetracycline; or no antibiotics.

Slaughter samples are being tested for the presence of pathogens (salmonella and campylobacter). Other work on bacterial isolation and antibacterial sensitivities is ongoing, says Straw. Project completion is slated for spring 2004.

“Much of the work on effectiveness of growth promotants was done years ago in systems that are not representative of today's facilities and flow,” says Straw. “It is time to reassess the impact of antibiotics on performance, health and the development of resistance in the grow-finish period.”