Retreiving The Advantage Of Antibiotics Biology Essay

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Antibiotics are certainly major contributors to health improvement for humans and animals alike. Most of the antibiotics produced in the United States are customarily fed to farm animals to increase growth in non-therapeutic situations (Mellon and Benbrook, 2001). This abuse of antibiotics facilitates antibiotic-resistance in bacteria so that typical antibiotics used to treat various diseases become ineffective (Talaro, 2008). Statistics reveal an alarming increase in the prevalence of antibiotic-resistance by many pathogenic bacteria in recent years (S. aureus, 2007). If this potentially ominous situation is ignored, a future pandemic, without remedy, could threaten mankind. However, there is evidence suggesting that ending animal agriculture antibiotic abuse will allow for the reduction of antibiotic-resistant traits in bacteria to levels that will regain the advantage of antibiotics (Johnsen, et al., 2009).

Retrieving the Advantage of Antibiotics by Eliminating their Abuse in Animal Agriculture

The ability to artificially produce, in a laboratory, the antibiotics normally made by many bacteria in nature, is one of the great achievements of science. These antibiotics are used to eliminate harmful bacteria that infect humans and animals, thus curing many diseases. Yet, society is on the verge of letting the benefits of this success slip away because of its appetite for economical meat. Crowded farms, where animals are grown for food purposes, use antibiotics to control disease and promote growth. If these two objectives are met, it will help keep the price of meat down (Goldman, 2004). Nevertheless, this action not only eliminates pathogenic microbes, it also destroys bacteria normally present that keep potentially pathogenic microbes under control. Additionally, when antibiotics kill susceptible strains of bacteria, modified strains of the bacteria that are resistant to the antibiotic will be the sole survivors, not only selectively increasing the population of resistant bacteria, but eventually passing on the resistance trait to normally susceptible pathogens. Bacteria also have the ability to pass on this antibiotic-resistant trait to entirely different species of bacteria (Goldman, 2004; Talaro, 2008). These resistant bacteria will likely inhabit the animals, possibly contaminating the meat. If they are disease causing, such as Salmonella, Staphylococcus aureus, and some strains of Escherichia coli, then people who become infected with resistant bacteria cannot be restored to health by antibiotics to which the bacteria are resistant (Goldman, 2004).

Investigation by the Union of Concerned Scientists approximates over 84% of antibiotics produced in the U.S. are given to animals in animal agriculture, and most of this is used for non-treatment purposes. Comparatively, only 13% of antibiotics are used to treat humans. (Mellon and Benbrook, 2001; Fig. 1). Antibiotic-resistant bacteria can also contaminate produce when animal manure contaminates the water supply for irrigation for fruits and vegetables, which can then infect humans (Beauchat and Ryu, 1997).

However, there is hope for this seemingly hopeless situation. A study of one type of antibiotic-resistant bacteria, following the 12 year ban of an animal growth promoter, concluded that there was a dramatic decrease in levels of resistance, indicating that in the absence of antibiotics, resistance traits can eventually mutate back to a previous condition of susceptibility (Johnsen, et al., 2009). Another 2009 study, comparing the antimicrobial effect of lavender oils on bacteria, did indicate inhibition of growth (Roller, et al., 2009). These two studies allow for optimism that there is potential for a reversal of the resistance problem if proposed legislation can be implemented and changes are executed. It is believed that the rendering of prior research will lead readers, who may be unfamiliar with antimicrobial mechanisms and the consequences of their impotency, to the following conclusion: it is of utmost importance that the habitual use of antibiotics in animal agriculture be abolished, in order to reduce levels of antibiotic-resistant microbes and regain the effectiveness of available antibiotics in fighting disease.


The normal condition of most bacteria is sensitivity to the majority of antibiotics. Antibiotics are naturally produced by various species of molds and bacteria, creating an environmental advantage for those species to survive in the presence of other microbes. Therefore, there is always a low basic exposure level to antibiotics in nature, and hence, a corresponding low level of antibiotic resistance naturally existing in bacteria populations. However, bacteria are typically very efficient and usually do not retain traits that are unnecessary for survival because exhibiting such traits adds a biological burden that makes them less efficient (Talaro, 2008). Thus, over time, in the absence of continual antibiotic exposure, the resistant trait is prone to be lost. This is a pertinent aspect that must be considered if the world is to recover the effectiveness of antibiotics that has been lost due to their abuse (Goldman, 2004).

Statistics for Antibiotic Use in Animal Agriculture

The Union of Concerned Scientists (UCS), founded in 1969, reports that 78.5% of antibiotics produced in the U.S. is used for non- treatment purposes in livestock and another 5.7% is used to treat actual diseases in livestock. Pesticide purposes account for 0.1% of antibiotic usage and 2.8% is used to treat domesticated animals. Antibiotic use in humans, including soaps and disinfectants amounts to only 13% of the total usage (Table 1). Non-treatment antibiotic use for animal agriculture is more than 600% of the total use of antibiotics in humans (Mellon and Benbrook, 2001).

Statistics for Mortality and Morbidity from Antibiotic-Resistant Bacteria

There are approximately 292,000 hospitalizations for Staphylococcus aureus infections annually in U.S. hospitals. Of these, approximately 126,000 hospitalizations are related to methicillin-resistant Staphylococcus aureus (MRSA) (S. aureus, 2007). The proportion of healthcare-associated staphylococcal infections that are due to MRSA has been increasing. According to the Centers for Disease Control and Prevention (CDC), proportions of S. aureus infections in U.S. intensive-care units due MRSA were 2% in 1974, 22% in 1995, and 64% in 2004 (Figure 2). Approximately 32% of the U.S. population is colonized with S. aureus and 0.8% is colonized with MRSA. The proportion of Staphylococcus aureus isolates that were MRSA increased from 35.9% in 1992 to 64.4% in 2003 for hospitals in the National Nosocomial Infections Surveillance system (S. aureus, 2007). CDC statistics state that of the 2 million patients who get an infection in the hospital each year, 90,000 will die. Over 70% of these infections are caused by bacteria resistant to at least one of the most common antibiotics used to treat them and "persons infected with drug-resistant organisms are more likely to have longer hospital stays and require treatment with second- or third-choice drugs that may be less effective, more toxic, and/or more expensive" (Campaign to prevent, 2001).

Studies and Results

Examining the Problem

A study of the presence of MRSA in farm animals and farm workers was conducted to demonstrate the relationship of an animal being infected with MRSA and transmitting it to humans. The nostrils of 299 swine (representing approximately 87,000 live animals) and twenty workers from two different farm systems in Iowa and Illinois were sampled and typed for MRSA isolates. The overall incidence for MRSA in swine was 147 (49%) and 9 (45%) in workers. The incidence of MRSA presence among farm system A swine varied by age, ranging from 11 out of 30 (36%) in adult swine to 60 out of 60 (100%) in animals aged 9 and 12 weeks. The incidence among farm system A workers was 9 out of 14 (64%). There was no MRSA detected in farm system B swine or workers. Researchers concluded that colonization of swine by MRSA with transmittance to workers was very common on one farm system while it did not exist on the other farm system, "suggesting that agricultural animals could become an important reservoir for this bacterium"(Smith, 2009, p. 4).

It is not just MRSA that is a problem. For example, there are several strains of multidrug-resistant Salmonella (MDRS). Salmonella typhimurium, including multidrug-resistant Salmonella typhimurium type 104, causes almost 10% of Salmonella infections among humans in the United States, according to Kathleen Glynn. Her study revealed that S. typhimurium infections resistant to antibiotics were much more likely to have received an antibiotic, especially one to which the Salmonella culture had become resistant, during the 4 weeks before illness onset. Researchers concluded that "prudent antimicrobial agent use among humans and among veterinarians and food-animal producers is necessary to reduce the burden of drug-resistant salmonellosis in humans." (Glynn, et al. 2004, p. 227).

David White (2001, p. 1147) agrees, expressing that "salmonella is a leading cause of food-borne illness. The emergence of antimicrobial-resistant salmonella is associated with the use of antibiotics in animals raised for food; resistant bacteria can be transmitted to humans through foods, particularly those of animal origin." White's research team identified and characterized strains of salmonella isolated from 200 ground meat samples purchased in the Washington, D.C., area. Salmonella was discovered in 41 samples (20%), with a total of 13 serotypes. Isolates were resistant to at least one antibiotic in 84% of samples, and 53% of isolates were resistant to at least three antibiotics. The obvious conclusion was that salmonella strains resistant to antibiotics are common in market ground meats (White, 2001). This study provided the evidence calling for "adoption of guidelines for the prudent use of antibiotics in food animals and for a reduction in the number of pathogens present on farms and in slaughterhouses. National surveillance for antimicrobial-resistant salmonella should be extended to include retail meats" (White, 2001, p. 1147). There are other studies in abundance concluding that antibiotic abuse leads to contamination of food animals and produce by antibiotic-resistant microbes that will eventually infect human beings.

Exploring Solutions

A 2009 study investigates the glycopeptide-resistant enterococci in Dutch poultry farms twelve years after the ban of the animal growth promoter avoparcin, which is carcinogenic and causes vancomycin-resistance. Researchers reviewed mechanisms of resistance, rates of reacquisition, effects of resistance traits on bacterial health, linked selection, and ability of resistance factors to remain stable after separation from fundamental genetic material. Results indicated that eradication was not entirely complete, but that "resistance determinants may persist at low, but detectable, levels for many years in the absence of the corresponding drugs" (Johnsen, et al., 2009, p. 357). This evidence suggests that even though antibiotic-resistance is not eliminated by banning the use of certain antibiotics, restricting their use does serve in returning resistance levels closer to normal. Other research is uncovering evidence that infections can be fought in other ways.

Another 2009 study compares the antimicrobial effect of four different lavender oils on methicillin-sensitive and methicillin-resistant Staphylococcus aureus (MSSA and MRSA). All four lavender oils inhibited growth of both MSSA and MRSA by direct contact, although not in the vapor phase (Roller, Ernest, & Buckle, 2009). This study is important because results suggest that combinations of lavender oils should be investigated further for possible use in antibacterial products. This type of complementary disease treatment could be especially beneficial in fighting antibiotic-resistant microbes while reducing the use of antibiotics.

Pending Legislation

Public officials are becoming more aware of the massive risk to society's health and the difficulty that the Food and Drug Administration has had in trying to limit antibiotic use. "The Preservation of Antibiotics for Medical Treatment Act," originally proposed in Congress in 2002 and again in 2009, would ban this reckless abuse of antibiotics in animal agriculture (Slaughter introduces bill, 2009).


The general public must have a prescription to obtain antibiotics but the animal agriculture business is permitted to use them carelessly. "This irresponsible misuse of antibiotics is unilaterally disarming our species from our precious last line of defense, and devastating epidemics of historical proportions may be the legacy of the hunger for inexpensive meat" (Goldman, 2004). Research indicates a clear relationship between an animal being infected with antibiotic-resistant bacteria and passing it on to humans (Smith, 2009) and that these infections are much more likely to have received an antibiotic (Glynn, et al. 2004). Furthermore, it has been revealed that antibiotics are common in retail ground meats (White, 2001). Meat prices may be lower because of antibiotics but their abuse is causing infections due to antibiotic-resistance to increase, along with mortality rates and health insurance costs (Campaign to prevent, 2001). Fortunately, research has also shown that antibiotic-resistance can be decreased to more tolerable levels by discontinuing antibiotic misuse (Johnsen, et al., 2009, p. 357). Moreover, there are proven alternatives to microbial-control to be further explored (Roller, Ernest, & Buckle, 2009). Contacting relevant political officials to support approval of "The Preservation of Antibiotics for Medical Treatment Act," which will halt casual antibiotic use, may be the most effective mode of action possible in retrieving the advantage of antibiotics (Slaughter introduces bill, 2009). If beings on this planet are to thrive and avoid serious health consequences, it is of paramount significance to regain the advantage of available antibiotics in fighting disease by eliminating the routine use of antibiotics in animal agriculture.