The discovery of penicillin by Sir Alexander Fleming in 1928 revolutionized modern medicine. Since its early use of treating bacterial infections from flesh wounds during World War II, antibiotics have now become ubiquitous in their use, and have globally saved millions of lives. It is precisely this widespread, and at times exaggerated use, that is now threatening to create a public health crisis with the creeping rise of antibiotic resistant strains of bacteria.
Antibiotics are able to selectively kill bacterial cells, without harming human cells, by targeting molecules or processes specific to bacteria. Unlike human cells, bacteria contain cell walls, a protective layer composed of peptidoglycans molecules. Penicillin exerts its bactericidal function by targeting peptidoglycan cross-linking, thus compromising the integrity of the bacterial cell wall, rendering it susceptible to osmotic lysis or bursting.
The generation of antibiotic resistant bacteria is the unfortunate consequence of the extensive use and misuse of antibiotics. Even as early as in 1945, Sir Alexander Fleming warned of danger by saying, “the public will demand [antibiotics].. then will begin an era.. of abuses.” During routine use of antibiotics, most of the bacteria will not survive antibiotic treatment. However, in some cases, particularly when patients stop taking antibiotics earlier than prescribed as they begin to feel better, a few bacteria will survive the treatment. With each generation of bacteria, small random mutations will develop. The trouble arises when one of these mutations results in resistance to the antibiotic, conferring a selective advantage to this particular bacterium. This particular mutation that offers protection is then spread either by horizontal gene transfer (where bacteria transfer genetic information through a circular piece of DNA called a plasmid) or by passing on this mutated gene to the progeny bacteria.
Although resistance may arise with any course of antibiotics, it is the use of antibiotics in mass quantities that has most significantly contributed to the public health problem. In Western countries, antibiotics are often overprescribed to patients by doctors, despite warnings from health professionals. Doctors are sometimes pressured into prescribing antibiotics for treatment of illnesses that have not yet been confirmed to be of bacterial origin. In many countries, antibiotics are available over the counter and are routinely and erroneously taken by the public to treat viral infections, against which they have no efficacy. The results of several studies have indicated that antibiotics are incorrectly prescribed or taken in about 30-50% of cases.
Another contributor to the development of antibiotic resistant bacteria is the abundant use of antibiotics for growth supplements in livestock. In fact, agriculture is responsible for using approximately 80% of the antibiotics distributed in the US. Any antibiotic resistant bacteria that develop in livestock can reach humans after consumption of the infected animals. Livestock antibiotic use can also promote the development of antibiotic resistance in the environment as treated animals excrete the antibiotics through their urine and stool, distributing the drugs through soil and groundwater. Additionally, antibiotics are commonly sprayed on fruit trees as pesticides, and are included in household cleaning products. These practices contribute to the development of antibiotic resistant bacteria by increasing bacterial exposure to antibiotics.
This looming crisis is further exacerbated by the fact that most pharmaceutical companies are not investing in research to develop new antibiotics. Out of the 18 largest global pharmaceutical companies, 15 have completely pulled out of re-searching new antibiotics. As antibiotics are generally only used for a short period of time, are often curative and relatively low cost, they are not as financially lucrative as other drugs may be, meaning there is very little incentive for pharmaceutical companies to spend time and resources to develop new antibiotics. In addition, due to the rise of antibiotic resistant bacteria, doctors save any newly generated antibiotics as a “last-line” treatment, and therefore do not widely prescribe them, thus making any newly developed antibiotics even less profitable than manufacturing existing ones.
Unfortunately, the development of antibiotic resistant organ-isms, also known as superbugs, has resulted in a global crisis. Those most significantly affected are often living in tumultuous conditions, affected by war, famine and natural disasters. In the future, simple cuts or scraps could result in life-threatening infections. In order to circumvent this future, new, more effective antibiotics need to be manufactured. Or, better yet, new mechanisms of eliminating the harmful bacteria should be developed. Phage therapy is an option which uses bacterial viruses, bacteriophages, to target bacteria. Additionally, public health policy measures need to be established in order to control the use of antibiotics to reduce the development of resistant bacteria. With global dedication and informed policies, the world may avoid far-reaching illness due to the superbugs created by the selective pressure of evolution.
Sarah Colpitts
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