Antibiotic stewardship: not a burden for animal agriculture alone

Antibiotic stewardship: not a burden for animal agriculture alone

By Bill Hsu

Incidence of antibiotic resistant bacterial infections are higher than ever, and the Centers for Disease Control and Prevention (CDC) note that at least 23,000 people die each year as a direct result of these infections.  It’s no wonder then, that fears of rampant superbugs are fueling the debate about responsible antibiotic usage, and much of the talk centers around antibiotics used in animal agriculture.  The same fungi spores that bore our first antibiotics find other use in the food industry though.  After all, it does take Penicillium to make blue cheese or Roquefort.  Much like some cheeses though, the debate surrounding is chock full of holes. 

California Senate Bill 27 (SB27) was signed October 2015 to combat what was described as widespread and unregulated use of antibiotics in animal agriculture at low or sub-therapeutic doses to increase weight gain in animals before they went off to slaughter.  SB27 expressly prohibits use of medically important antibiotics in animals unless they were prescribed by a veterinarian.  It also bans the use of antibiotics used for growth-promotion. 

SB27 references the Food and Drug Administration’s Guidance for Industry Document #152 (GFI 152).  These are rules the FDA proposed to classify different antibiotics important in human medicine into three categories: important, highly important, and critically important.  The list is extensive and includes highly specific-use antibiotics, as well as broader spectrum antibiotics that you might get from your doctor if you have a small infection.  This list, however comprehensive, is mostly meaningless in trying to limit antibiotic usage in California’s food producing animals.

Antibiotics generally have multiple indications on their label.  Macrolides and tetracycline are both classes of antibiotics that make an appearance on GFI 152.  These classes of antibiotics are also some of the most commonly used antibiotics in animal agriculture.  Based off those two facts alone, you’d suspect that using these two classes of antibiotics to promote weight gain is rampant in animal agriculture, but you’d be wrong.  You see, these antibiotics have several indications on their label. 

When a licensed veterinarian writes a prescription, or in this case, assigns a feed directive for a farm, he or she is prescribing the same antibiotics we mentioned were used to promote weight gain in animals—albeit, in higher concentrations.  You read that right—when you’re treating animals to prevent disease in areas of exposure risk, you’re using the more of the same antibiotics you were trying to limit use of!

But does it even matter?  The Summary Report on Antimicrobials Sold or Distributed for Use in Food-Producing Animals from the FDA highlights that the two largest classes of antibiotics used domestically in agriculture are tetracycline (which you or I can buy today) and ionophores, which serve no function at all in the human body.  Together, these two account for about 3/4^th of all antibiotics used in agriculture.  Our most valuable antibiotics, those classified as critically important in human medicine, including 3^rd generation Cephalosporins and Flouroquinolones, see the heaviest usage in healthcare.  In fact, each of these account for less than 1% of usage in animal agriculture.  The fear of prolific superbugs spelling our demise is driving action like SB27, but the CDC  spells it out clearly—most deaths related to antibiotic resistance happen in healthcare settings such as hospital and nursing homes.

Antibiotic stewardship is a responsibility we all share.  With the discovery of penicillin, antibiotics have shaped what we know of modern medicine.  Antibiotics are powerful tools, but have a very finite practical life.  Investment in alternative practices in animal agriculture, including vaccines and animal management can help draw down total usage numbers.  Physicians dialing back antibiotic scripts, except in the most important cases can help prevent abuse of our most essential antibiotics.  Finish your antibiotics as prescribed.  Don’t flush extra pills down the drain.  A concerted effort to managing antibiotics, from all fronts, is necessary to address growing threats of resistance.

Attention spans are short and opinions are heard louder than ever.  Shifting the focus solely to agriculture while ignoring healthcare data, or making only symbolic attempts at bandaging the very real problem of overuse of antibiotics, especially of those critically important in human medicine, mean we will someday lose our best tools in healthcare.  Remember that for the future, whether it’s a doctor’s office you find yourself in or the meat and cheese display at your local deli.