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| from USDA |
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.
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