Is your Food Antibiotic-free?

Updated March 04, 2015.

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

The label on the plump chicken said "Antibiotic-Free". Not just organic, free range, heritage, hormone-free, but Antibiotic-Free.

What does this mean?

Small amounts of antibiotics are used as to promote growth of farm animals. There are many farm animals so even small amounts add up. Most antibiotics used in the US are used in farm animals; 80% of antibiotics used in the US are in animals.

This all started back in 1950.

Scientists saw astonishing growth of animals given vitamin B12. Then they realized: it wasn't the B12. It was the very tiny bit of antibiotic added to the vitamin. Livestock grew quickly and to larger sizes with lower costs if antibiotics were added. Soon, antibiotics were added to animal feed and given as injections.

Could this be a problem?

Anything that reduces the effectiveness of antibiotics is a problem. Each year in the US, 2 million are infected by antibiotic resistant bacteria. At least 23,000 die each year. People need antibiotics for lung and skin infections, urinary tract infections and diarrhea. Doctors are worried that bacteria may be able to evade the antibiotics we have if bacteria continue to collect drug resistance genes.

Why Do Antibiotics Stop Working?

Imprudent use of antibiotics leads to antibiotic resistance. This can be from large amounts in a patient in an intensive care unit or someone buying antibiotics over the internet.

This is also the case in food animals. As the CDC says "[antibiotic] use contributes to the emergence of antibiotic-resistant bacteria in food-producing animals".

The CDC additionally states,  "Food animals serve as a reservoir of resistant pathogens and resistance mechanisms that can directly or indirectly result in antibiotic resistant infections in humans."

Once the genie is out of the bottle, it's hard to stuff the genes for resistance back in. Gene mutations can allow bacteria to resist being killed or halted by specific antibiotics. When these antibiotics are used, the bacteria with these genes grow and grow, while the other bacteria strains do not. These genes can also jump from one bacteria to another.

Small amounts of antibiotics - less lethal, less likely to wipe out these bacteria - may let bacteria collect more resistance genes. If the antibiotics had been strong enough to wipe out the bacteria, there might not be a problem, but low, non-lethal, non-effective, levels let the bacteria have time to collect strains that are resistant. Persistent use of antibiotics drives the resistant bacteria to flourish.

Resistance genes can also spread among bacteria we don't think about - the billions and trillions of seemingly benign bacteria in our gut, skin, and elsewhere that are not causing infection. In fact, the growth promotion likely occurs through the effects of the antibiotics on gut flora.

How are antibiotics used?

Sometimes, small amounts of antibiotics are used in large amounts to a lot of animals, such as in feed or water. Other times antibiotic use is more directed; a vaccine for a common chicken disease is injected into eggs; an antibiotic is then injected to prevent infections created by the hole made by the vaccination. 

Aren't different antibiotics used in animals and humans?

Yes and no.

Some antibiotics are exactly the same, like say gentamicin. 

Some antibiotics are almost the same and lead to the same or similar genes for resistance. These drugs are from the same class of meds as human antibiotics. For instance, the US stopped the use of a class of drugs called fluoroquinolones in animal feed after one drug in this class (Baytril) was used in poultry and fluoroquinolone resistance was found in poultry bacteria. This resistance affects the use of drugs like Cipro, which we use for diarrhea and urinary tract infections. 

There are also other antibiotics used in farming are very different than those used in humans.

Could people pick up these resistant bacteria?

Yes, specific resistant bacteria have been shown to have been acquired from farms. For instance, one boy was shown to have picked up salmonella resistant to a very important drug (ceftriaxone) that could be traced back to a specific farm. Likewise, farmworkers and livestock veterinarians are at increased risk of picking up resistant bacteria.

Grocery store meats, including turkey, have been shown to carry these resistant bacteria. In fact, outbreaks of drug resistant bacteria have been led to meat recalls. 

Moreover, we know that feeding resistant bacteria obtained from meat to healthy volunteers results in bacteria remaining in their intestines for up to 2 weeks. 

However, human antibiotic-resistant bacterial strains are often different from strains found in grocery stores. Many of our resistant infections do not come directly from meat.

What are companies doing?

Companies have worked to reduce the antibiotics fed to their animals. Perdue Farms reduced antibiotic use substantially which it announced in Septemeber 2014. Other companies like Tyson, McDonalds, and Chik Fil A have announced limiting or stopping use of antibiotics.

What is the government doing?

The US FDA's has worked to have businesses voluntarily restrict antibiotic use. There has been a push to collect more data on antibiotic-resistance from live animals on farms. Others have worked to further encourage - or to specifically mandate - responsible use of antibiotics in livestock.