Our own gut bacteria may be perpetuating antibiotic resistance: study

LOS ANGELES, Dec. 18 (Xinhua) -- Antibiotic resistance among disease-causing bacteria is of global concern. Researchers have discovered that our very own gut bacteria may be perpetuating the resistance.

"What happens to gut bacteria when they are exposed to antibiotics over a long period of time?" Researchers from Arizona State University and Norwegian University of Life Sciences investigated gut bacteria in honey bees to explore the question.

According to the new research, published in the current issue of the journal Molecular Ecology, antibiotic-resistant genes are spread in honey bee gut bacteria so that all strains of bacteria survive, rather than just one gut bacterium acquiring resistance and outcompeting others.

"To our surprise, we found that instead of one gut bacterium acquiring resistance and outcompeting all the other gut bacteria in honey bees, the resistance genes spread in the bacterial community so that all strains of bacteria survived," Gro Amdam, a professor with ASU School of Life Sciences and co-author of the paper, was quoted as saying in a news release.

Researchers from Arizona State University and Norwegian University of Life Sciences uncovered this startling finding while investigating the microbial life in honey bee guts. While honey bees have a simpler microbial community in their guts compared to humans, they also have features in common.

"There is an important similarity between honey bee and human gut bacteria, in that some bacteria are in symbiosis with the host -- these are important for host health," said Jane Ludvigsen, a doctoral student with the Norwegian University of Life Sciences and lead author of the paper. "The bacteria we investigated are symbiotic for the honey bee, and they each have important functions. Because they must all be there for the host to be well, we think this is the reason that antibiotic-resistant genes have spread to all."

In this study, researchers focused on microbes that are resistant to tetracycline, which is an antibiotic that has been widely used for decades in human medicine and also to promote growth in animals, often in chicken, cattle and pig farming.

Tetracycline is also commonly sprayed on plants, including apple and pear trees, to prevent diseases such as fire blight, which can devastate crops. In the U.S., it has been used even on organic farms. In Norway, rules on antibiotic use in farming of any kind are much stricter, according to the study.

Many people believe that antibiotic-resistant bacteria are mainly found in places such as hospitals. And although dangerous microbes can be found there, they are also found in our everyday environments.

"Our paper predicts that if there is already antibiotic resistance in your gut, then most or all of your gut microbes will also carry this resistance. Basically, we've become potent reservoirs for carrying antibiotic-resistant genes," said Amdam. "This is not good news from an epidemiological point of view. If our paper is right, then from what we see in the U.S. and Norway, you can keep accumulating multiple versions of antibiotic-resistant genes. If pathogenic bacteria pass through your body, they can also pick up this resistance."

Next, the researchers say could be to study how the bees' gut selects for certain kinds of bacteria, and not others. Enditem