antibiotics have saved millions of lives, their efficacy is diminished over time because of antibiotic resistance. Many pathogens possess the ability to multiply and mutate rapidly in response to the presence of antibiotics, and those mutations that are the hardiest will survive, making successive generations even more resistant. To determine how these antibiotic resistant processes operate and what steps researchers have taken in response, this paper provides a review of the relevant peer-reviewed and scholarly literature, followed by a summary of the research and important findings in the conclusion.
The Evolution of Antibiotic Resistance
When it was discovered by Alexander Fleming in 1928, penicillin was widely hailed, and rightfully so, as a miracle drug. While penicillin and other antibiotics have in fact saved millions of lives over the past several decades, the tendency of many physicians to over-prescribe these medications as well as the proliferation of the use of antibiotics by the agricultural and aquaculture industries that find their way into the human food chain has further exacerbated the situation. Moreover, the ability of most pathogens to rapidly reproduce into enormous numbers makes the evolution of antibiotic resistance inevitable. Beyond the foregoing, studies have also cited a number of other causes for the evolution of antibiotic resistance including demand by healthcare consumers for antibiotics even when their use in contraindicated. As a result, the prevalence of antibiotic resistance pathogens such as methicillin-resistant Staphylococcus aureus in some tertiary healthcare facilities has reached epidemic levels, for example, and current signs indicate these trends will continue in the future. To gain some fresh insights in this area, this paper provides a review of the relevant peer-reviewed and scholarly literature concerning the evolution of antibiotic resistance, followed by a summary of the research and important findings in the conclusion.
Materials and Methods
This paper used peer-reviewed and scholarly resources published in the English language from public and university libraries, as well as reliable online research resources such as EBSCO and Questia, with an emphasis on the most recent resources.
The results of the literature review show that the ongoing battle against pathogens that are able to mutate and become resistant to antibiotics has become a national priority because of the potential threats to public health these trends represent (Brower & Chalk, 2003). For instance, according to Krist and Showsh (2007), the "widespread evolution of antibiotic resistance among pathogens [has] become a major public health threat" (p. 95). Before the introduction of antibiotics, of course, even minor wounds could become life-threatening as a result of infections, but the efficacy of these drugs tends to diminish over time as they are used with increasingly frequency and more resistant strains evolve. In this regard, Saver reports that, "Although once viewed as miracle drugs, antibiotics have turned out to be fragile weapons in the fight against infectious disease" (p. 431). These are important considerations for the healthcare community because the magic bullets these drugs once represented have become less effective over time. According to Saver (2008), "Antibiotic resistance undermines a drug's ability to treat illness. Problems with resistance can develop insidiously, as bacteria evolve, adapt, and otherwise change over time so that a medication previously thought useful in controlling the bacteria no longer proves effective" (p. 432).
Not surprisingly, these factors have combined to create a situation that represents a growing threat to the public health as well as causing billions of dollars in additional expenditures for already scarce healthcare resources. In this regard, Saver (2008) emphasizes that, "Antibiotic resistance menaces the population as a dire public health threat and costly social problem. The Institute of Medicine estimates that antibiotic-resistant infections generate costs as high as $4 to $5 billion per year in the United States" (p. 432). Unfortunately, these trends have created a slippery slope and the downward spiral appears irreversible at this point. For example, Saver adds that, "Antibiotic resistance appears to be not only on the rise, but accelerating. Alarming increases in infection rates have been observed for methicillin-resistant staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), drug-resistant forms of bacteria associated with hospital-acquired infection" (p. 432). In fact, the numbers of patients that die from MRSA alone (about 18,000) are estimated to exceed the combined totals for HIV-AIDS, Parkinson's, emphysema, and homicide (Saver, 2008).
Formulating effective responses for antibiotic resistance remains especially challenging because of the multifaceted nature of the problem which has a number of causes, including the following:
1. Weak surveillance for resistance;
2. Aggressive promotion of antibiotics by pharmaceutical companies;
3. Lax infection control practices;
4. Patients' irrational demand for antibiotics even when they may not be effective;
5. Unwarranted clinical variation in the way physicians prescribe and monitor use of antibiotics;
6. Inappropriate patterns of antibiotic use in agriculture and food-animal products that may impact human health; and,
7. A possible downturn in discovery and commercial development of new antibiotics (Saver, 2008, p. 432).
Of particular concern is the ability of many pathogens to rapidly mutate and evolve in response to the presence of many of the more commonly used antibiotics (Krist & Showsh, 2007). In reality, though, it is little wonder that many pathogens are able to evolve and mutate in ways that improve their resistance to antibiotics since they multiply rapidly and the enormous numbers that are involved virtually assures that some will be mutations that are resistant to antibiotics (Marshall, McGeer, Gough & Grootendorst, 2006). As a result, "Any mutation that can make a cell resistant is sure to occur in a few bacteria in a population; if the bacteria are able to survive the change to their cell functions caused by the mutation and to multiply, a resistant population can rapidly build up" (Charlesworth & Charlesworth, 2003, p. 79). Likewise, Denamur, Tenaillon, Deschamps and Skurnik (2005) emphasize the rapidity and enormous numbers of cells that are involved in pathogen reproduction and mutation because these two attributes are the essence of the evolution of antibiotic resistance. In this regard, Denamur and his associates note that, "The comprehension of how cells having high mutation frequencies arise and proliferate is important for the understanding of the evolution of antibiotic resistance. In vitro and in vivo studies show that high mutation frequencies can significantly contribute to the appearance of multiresistant bacteria" (2005, p. 825).
Although the practice of physicians over-prescribing antibiotics is frequently cited as the primary cause of increasing antibiotic resistance, there are other sources of antibiotics for humans that have contributed to these trends in recent years as well. For instance, there has been a growing recognition of the inextricable connections that exist in the ecosystem, especially with respect to the risks these connections pose for human health as a result of antibiotic-resistant pathogens caused by the widespread use of antibiotics to facilitate rapid growth in farm animals and in aquaculture environments to reduce disease in high-density fish enclosures (Aquirre, Ostfeld, Tabor, House & Pearl, 2002). In recent years, some of these animal-based antibiotic-resistant pathogens have been the source of infection for humans as well (Aquirre et al., 2002). In this regard, Charlesworth and Charlesworth (2003) caution that resistance is a natural concomitant to the use of antibiotics and there is little that can be done to avoid this tendency. For instance, these researchers emphasize that, "Drug and pesticide resistance evolve whenever drugs are used to kill parasites or pests, and literally hundreds of cases have been studied in microbes, plants, and animals" (Charlesworth & Charlesworth, 2003, p. 80). The inevitability of mutations that contribute to enhanced antibiotic resistance is also reinforced by the fact that these transformations do not carry any particular downside for the pathogen, but rather further enhance its ability to reproduce in hostile environments and thrive (Charlesworth & Charlesworth, 2003). For instance, Charlesworth & Charlesworth report that, "Sooner or later, bacteria will evolve so that they survive well in the presence of antibiotics, without serious costs to themselves. Our only chance is therefore to use antibiotics sparingly, confining use to situations where they are really needed, and making sure that all infecting bacteria are killed quickly, before they have time to evolve resistance" (p. 80). Because some patients may stop taking their prescribed antibiotics when their symptoms diminished or cease, the efficacy of these drugs will be adversely affected and may even backfire as these pathogens gain even more resistant qualities and then be transmitted to yet more human hosts (Charlesworth & Charlesworth, 2003). In this regard, Charlesworth and Charlesworth report that, "If one stops treatment while some bacteria remain present, their population will inevitably include some resistant bacteria, which can then spread to other people" (2003, p. 80).
Antibiotic resistance can also spread between bacteria, even ones of different species. Antibiotics given to farm animals, to keep infections down and promote growth, can cause resistance to spread to human pathogens. Even these consequences are not the whole of the problem. Bacteria that have resistance mutations are not typical of their populations, but sometimes have higher mutation rates than average, allowing…