What Can 4 Million Old Antibiotic Resistant Bacteria Teach Us?

Posted on | April 12, 2012 | Comments Off on What Can 4 Million Old Antibiotic Resistant Bacteria Teach Us?

Mike Magee

Over the years, I’ve had exposure to basic science researchers focused on infectious diseases both in academia and industry. In both environments, I witnessed legitimate concern regarding the inappropriate and overuse of antibiotics and the link to increasing resistance to antibiotics among human pathogens. The issues include exposing patients to long term danger, limiting the availablity of effective therapies, waste of limited health resources, and placing researchers under increasing pressure to stay one step ahead of harmful microorganisms.

One contentious issue has been the use of antibiotics in animal feed. This use has accelerated over the years. Why? First, the Concentrated Animal Feeding Operation, otherwise known as the “factory farm.” In one farm, 37,000 cows are raised for slaughter at one time and consume 1 million pounds of feed a day, 75% of which is corn. What’s remarkable about this is that cows naturally and historically feed on grass, not corn. But as corn became cheaper, cows were confined in pens side by side and force fed, and the results were dramatic. In 1930 it took 4 to 5 years to bring a cow to 1200 pounds for slaughter. Today it takes just 16 months. The unnatural diet has had health implications for the cows, like stomach perforations and liver abcesses requiring the addition of antibiotics and other medicines to the feed.(1)

This week the FDA initiated step one in addressing the issue. They have asked for the animal industry over the next three years to voluntarily eliminate the use of routine antibiotics in feed as growth enhancers. Mandatory enforcement might occur at the end of this term if voluntary compliance is not working. Most have applauded this action as it makes general sense that the more pathogens are exposed to antibiotics, the quicker they will learn to neutralize them through mutation and render the medications useless.(2)

In reality, as is so often the case in science, human understanding of this issue is far from complete. We know for sure that certain microorganisms are harmful, even deadly to humans. We know as well that in nature, and even inside the human body, microorganisms are essential to daily function and tend to counter-balance and control each other. And we know that microorganisms which are sensitive to antibiotics can, over time become desensitized. We believe this is more likely with intense exposure to the antimicrobial agents, and we believe humans have played a role in this – by over using the agents themselves and by inserting them into the human food chain.

But as is so often the case, what we think we know is often challenged by new bits of knowledge that come along. For example, on the very day that the FDA released it’s guidelines this week, microbiologist Gerard D. Wright and colleagues reported out their findings on 93 strains of bacteria that had never been exposed to humans in the journal PLoS ONE.(3) Where did they come from? Veteran spelunker and University of Akron microbiologist, Hazel A. Barton (photo above), gathered them from the deepest recesses of Lechuguilla Cave, whose 130 miles of tunnels stretch beneath New Mexico’s Carlsbad Caverns National Park. The bacteria have lived there for an estimated 4 million years fighting off a variety of foes – none of them human.

And here’s the kicker. When the bacteria were exposed to 26 different antimicrobials, 70% of the gram-positive strains and 65% of the gram-negative strains were resistant to three or more of the agents. Only tetracycline was effective against all of the micro-organisms.(3) Scientists registered wonder. Eileen Choffnes, director of the Institute of Medicine’s forum on microbial threats, said “the new research demonstrates that antibiotic resistance emerged millions of years before those medicines were used — and in an environment far too forbidding for the bacteria to have come into any contact with the drugs.” Lead author Dr. Wright commented, “”It’s awe-inspiring. It gives you real respect for the genetic diversity and the ability of these organisms to evade toxic molecules.” And Dr. Brad Spellberg, an infectious disease researcher at the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center thought aloud, “This pushes it way back. There’s never going to be a point where we can say, ‘OK, we’re up, we’re ahead, they’re done.’ “(4)

I can just imagine the old timer researchers of my vintage thinking, “This is exhausting – those bugs will never give up.” Luckily young blooders like spelunker scientist Barton are all in. “As a scientist, that’s what you live for. Just like in cave exploration, it’s the discovery of the unexpected that keeps you going back for more.”(4) And that takes us full circle. In policy as in science, absolute certainty is the enemy. We should never be so timid as to limit progress or experimentation, nor ever so confident or arrogant as to not leave room for the unexpected or be resistant to admitting when our strongly held convictions have been wrong.

For Health Commentary, I’m Mike Magee

References:

1. Pollan M. Omnivore’s Dilemma. 2006. http://michaelpollan.com/books/the-omnivores-dilemma/

2. FDA Takes Steps To Protect Public Health. April 11, 2012. http://www.fda.gov/NewsEvents/Newsroom/PressAnnouncements/ucm299802.htm

3. Bhullar K et al. Antibiotic Resistance Is Prevalent In An Isolated Cave Microbiome.

4. Healy M. Subterranean Bacteria Are Prepared To Survive Antibiotics. Los Angeles Times. April 11, 2012. http://www.latimes.com/health/la-he-antibiotic-resistant-bacteria-20120412,0,6511188.story