Antibiotic Resistant Bacteria and Industrial Farms

from USDA

During a recent training session on local, sustainable agriculture we engaged in a discussion about CAFO concentrated (or confined if you are sitting at Virginia Tech) animal feed lots. The discussion lead to thoughts on antibiotic use on industrial farms and antibiotic use in general.

According to the Center for Disease Control, CDC, antibiotic resistance is one of the world's most pressing public health problems. Practically every known type of bacteria has become less responsive to antibiotic treatment. These antibiotic-resistant bacteria strains can quickly spread within a hospital and the greater community. Peopled infected with antibiotic resistant bacteria tend to shed the bacteria from the nose, feces, and skin; therefore, the bacteria can end up spread by direct contact with a person, through surface contact, ventilation and in municipal wastewater streams after being washed down the drain or flushed down the toilet and spread in ways beyond direct contact. For this reason, antibiotic resistance is among CDC's top concerns.

Usually, antibiotics kill or inhibit the growth of susceptible bacteria. Antibiotic resistance, the acquired ability of a pathogen to withstand an antibiotic arises from random mutations in existing genes and allows the bacteria to survive exposure to antibiotics and other antimicrobial products, in the human body, in animals, or the environment. In a favorable environment the resistant bacterium can multiply and replace all the bacteria that were killed off. Chronic exposure to antibiotics can provide the selective pressure to make the surviving bacteria more likely to be antibiotic resistant. In addition, bacteria that were at one time susceptible to an antibiotic can acquire resistance by acquiring genetic material, pieces of DNA, that contain the resistance properties from other bacteria. The DNA that carries the code for resistance can be grouped in a single easily transferable package in bacteria. This means that bacteria can become resistant to many antibiotics and antimicrobial agents because of the transfer of one piece of DNA.

Though there is consensus among scientists that overuse of antibiotics has caused the increase in resistance, the actual cause of that resistance has been under debate. It is important to note that for every antibiotic, there are sensitive strains, which are killed or inhibited by the drug, and naturally resistant strains and resistance resulting from mutations. When a sensitive strain gains the ability to withstand an antibiotic, it becomes antibiotic resistant. The rate of antibiotic resistance emergence is related to the total amount of antibiotics used and the environment that resistant bacteria are in. The CDC believes that a major factor behind the spread of resistance in hospitals may actually be a lack of adequate hygiene and sanitation, which enables rapid proliferation and spread of pathogens. There are three general category of antibiotic and antimicrobial use that have been blamed for the increase in antibiotic resistant bacteria; misuse and overuse of antibiotics in treating human populations, household use of antibacterials in soaps and other products, and the addition of antibiotics to livestock feed.

Until recently the exact source of antibiotic resistant bacteria was just speculation and inference. Now using genetic sequencing of the bacteria scientists can trace antibiotic resistant bacteria to their source and hopefully to their cause. This methodology was used at the National Institute of Health (NIH) hospital in Bethesda to identify the chain of transmission in a deadly outbreak of antibiotic resistant Klebsiella pneumonia bacteria that infected 18 patients, seven of whom died. The genetic sequencing was used to identify the chain of transmission-body contact and equipment that spread the bacteria, and was able to guide a series of small steps including fumigation and (confirmed) sterilization of equipment, improved hand washing, isolation, and earlier detection to end it. The outbreak at the NIH hospital was ultimately stopped, but our vulnerability to these types of antibiotic-resistant bacteria is sobering. There are nearly 100,000 deaths a year in the U.S. attributed to hospital acquired antibiotic resistant infections, and these types of infections are appearing out in the greater community. This use of genetic sequencing could transform the way hospital-acquired infections are identified and halted saving tens of thousands of lives, but could also be used to tie antibiotic resistant bacterial infections in the community to their cause.

Research underway at The George Washington University, Department of Environmental and Occupational Health lead by Professor Lance B. Price is investigating the connection between antibiotic resistant bacteria present in our food supply and antibiotic resistant infections appearing in the general public. The NARMS retail meat surveillance a collaboration between the U.S. Food and Drug Administration/Center for Veterinary Medicine (FDA/CVM), the CDC, and State public health laboratories in 11 states sampled and tested meat purchased in grocery stores from January to December 2011. Each of the 11 laboratories purchased approximately 40 food samples per month, 10 samples each of ground turkey, pork chops, ground beef and chicken. The found that in 2011 that of meat from supermarkets 81% of ground turkey, 69% of pork chops, 55% of ground beef and 39% of chicken contained antibiotic-resistant bacteria.

The George Washington University researchers working with the Translational Genomics Research Institute in Phoenix (where the testing and sampling are taking place) are trying to quantify how extensively antibiotic resistant bacteria from the meat purchased in grocery stores is infecting people. Specifically, Dr. Price and his team are comparing the genetic sequences of antibiotic resistant E. coli bacteria from grocery store meat samples to the genetic sequence of the E. coli bacteria that have caused urinary infections in women. Though antibiotic resistant bacteria in meat is believed by Dr. Price to cause only a fraction of urinary infections, that could still amount to several hundred thousand infections each year.

The Food and Drug Administration reported that, in 2011 the last year for which they have data, almost 30 million pounds of antibiotics were sold for use in food animal production; however, according to Dr. Price more detail is needed on the use of antibiotics. At a congressional subcommittee hearing this spring Dr. Price said “we need to know why antibiotics are being used—that is, how often they are sold for non-therapeutic production purposes like growth promotion and disease prevention or for therapeutic purposes like disease control and treatment. These practices pose a particular threat to human health because they involve low-dose antibiotics, which can do more harm than therapeutic doses. They create an environment for bacteria that is just hostile enough to prompt them to develop resistance but not so harsh that they are killed off.”

Dr. Price's results when published this fall may provided the best reason to buy organic, sustainably raised meat.

Rethinking Organic

Recently, I read “Organic Inc.” by Samuel Fromartz. The book did two things, first it allowed me to understand the origins of organic food and how the concept of organic food has evolved with the regulation of the market and industry. The insight Mr. Fromartz provided to the organic food industry and farming made me rethink my position on organic food. Though traditionally, before the government stepped in to regulate the market, organic foods were grown under natural conditions (without the use of inorganic fertilizers, pesticides, or herbicides; and either not processed, or processed without the use of additives). Now, under standards adopted by the U.S. Agriculture Dept. (USDA) in 2000 and fully effective in 2002, organic food is food grown, raised and processed without synthetic fertilizers and pesticides, and antibiotics may not be used in raising organic foods, in addition, the use of irradiation, biotechnology, and sewer-sludge fertilizer is also banned. Food whose ingredients are at least 95% organic by weight may carry the "USDA ORGANIC" label; products containing only organic ingredients are labeled 100% organic.

However, under the government regulations the word "organic" refers strictly to the way farmers grow and process agricultural products, such as fruits, vegetables, grains, dairy products and meat. Organic farming practices are designed to encourage soil and water conservation and reduce pollution. Farmers who grow organic produce and raise organic meat don't use conventional methods to fertilize, control weeds or prevent livestock disease. The USDA organic label means that the food was produced using organic methods sanctioned by the USDA. So far there has not been any hard evidence that organic food is more nutritious of better for you. Food health studies are exceedingly difficult to run long term. So to a large extent the health benefits of not eating fruits, vegetables and grains with pesticide residue and meat without antibiotics and feed grain or grass without pesticide residue has to be taken on faith.

In the past I have bought organic where I thought it mattered to protecting my family from exposure to chemicals. Like strawberries, lettuce, apples, vegetables especially root vegetables where the outside of the fruit and vegetable is eaten. Other than that, I tried to buy only American grown produce, vegetables, herbs, beans and grains (though occasionally I do buy a couple of bananas). In terms of meat, I purchase organic, grass fed and pastured beef, pork, lamb and free range chicken. We only eat wild caught fish. I started buying grass fed beef back in the day when I was doing environmental evaluations of farms, dairies and concentrated animal feed operations (CAFOs). I will not go into the highly gross details of that work that have resulted in me barely ever eating meat. However, my concerns for the animal welfare, mad cow disease, and environmental impact of CAFOs pushed me to buy my meat from the first sustainable farm I inspected. In addition grass fed beef (and other animals) is lower in saturated fat and better for you. This was confirmed by Marion Nestle, author of “What to Eat” and Professor of nutrition at NYU School of Public Health. I asked her at a lecture I attended and she said that grass fed beef was as low in saturated fat as chicken.

Organic crop land is less productive than conventional farm land. Organic farming also requires more labor to keep weeds down. The average corn crop yield per acre in organic farming is 17 percent lower than down in traditional farming. Results range between 5 percent for corn to 35 percent for rye. For potatoes, root vegetables and turnips, crop yields are on average 14 percent lower than in traditional farming. In various fruits the yield was reported to be around 20% per acre lower with organic. That reduction in yield is basically why organic food sells for a premium. This loss of yield is an expense of organic farming, though there is a cost savings in not utilizing chemicals and in having soil retain its fertility through organic techniques of crop rotation. The chemical pesticides add to the cost of the crops in conventional farming, and conventional farming requires more irrigation water than organic farming.

Not only does conventional farming utilize more water, but the pesticide runoff impacts both surface and groundwater. The true cost of water is not expressed in the irrigation water charges in many places and the cost of the pesticide impact to water is not yet known and only recently have we begun to think about that impact. These days I am buying American grown organic to do my tiny part to protect the health of the soil, surface and groundwaters at least in my “neighborhood.”