Antibiotic overlaps in Animal and Human Health – Part 2

As I mentioned in my previous post, macrolides are part of human health, but they also are important to animal health, making up a sizeable portion of antibiotics used. It is my understanding that the use of macrolides in feedlot cattle, for instance, is a very effective preventive measure against liver abscesses. There are other FDA-approved uses of macrolides in animal health.

In 2011, macrolides accounted for approximately 4.3 percent of all antibiotics sold for use in animals.


Human health care providers wrote 5.3 percent of their prescriptions in 2009 for macrolides. The FDA has not taken steps to decrease this crossover at this time. I am assuming that this is because, based on its most recent National Antimicrobial Resistance Monitoring System (NARMS) report published in February 2013, very little resistance in bacteria to this class of antibiotics was seen, and certainly no upward trend of resistance.

The FDA has judiciously limited certain antibiotics from use in animals when NARMS and other monitoring efforts indicate a need for such action. When the FDA makes policy decisions, I want them based on biological science, not political science. The discussions occurring in the media and/or led by anti-agriculture activists are too often about eliminating all antibiotic use in animals except for therapeutic purposes. Other countries have tried this. Without antibiotics for growth promotion, Denmark saw an initial rise of 25 percent in the number of dead pigs.

The expected increase in illness rates not only led to lower weights and more costly meat, but also to therapeutic administration of high doses of antibiotics during a prolonged period of time. The use of antibiotics to treat sick animals in Denmark has risen 110 percent in 10 years. During this same time period, there was no drop in the incidence of antibiotic resistant in bacteria, while more animals suffered and were treated with more antibiotics.

RaymondDenmarkAntimicrobialGraph-Part2Scientists know that when a living animal, including you, is treated with an antibiotic not all the bacteria always die. Some mutate, develop resistance to the antibiotic and live within our bodies and the environment. It seems to me that by treating larger numbers of animals with significant bacterial infections with higher doses of antibiotics, we will only see more resistance.  I would ask – is it not safer for my health to treat larger numbers of animals with lower doses of antibiotics for a shorter period of time to prevent colonization and growth by a very limited number of bacteria?

I hope our policymakers can learn from the Danish Experiment and make informed decisions that protect both human and animal health, and help provide us with a safe and affordable supply of animal protein.

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