On Sept. 21 2016, the United Nations General Assembly held a meeting at their headquarters in Manhattan to discuss a growing problem that could endanger the health of every person on the planet. The day-long event featured Member States, non-governmental organizations, civil society, the private sector and academic institutions all providing insight and input on the issue at hand. The U.N.’s event described how the purpose of the meeting “is to summon and maintain strong national, regional and international political commitment in addressing antimicrobial resistance…” (The United Nations, “High-level meeting on Antimicrobial Resistance,” 09.20.2016).
Antimicrobial resistance is when a microbe evolves an increased or total resistance to agents that formerly were able to eradicate or contain it. The more commonly cited term is antibiotic resistance, which falls under the previously stated definition because bacteria are a type of microbe. The World Health Organization states that Antibiotic resistance “is one of the biggest threats to global health today. It can affect anyone, of any age, in any country” (World Health Organization, “Antibiotic Resistance.” 10.15.2015). Since bacteria developing resistances to deleterious environmental conditions has been occurring naturally for over three billion years now, why now is their evolution and adaptation a cause for global concern? To answer this question, a truncated explanation of the mechanisms behind bacterial immunity and how antibiotics work is necessary.
The main thing to know about antibiotics is that they work on parts of bacterial cells that are different than human cells so that they do not harm the patient. For example, bacterial cells have a carbohydrate-rich cell wall surrounding them to give the cell structural support. An antibiotic could be a molecule that inhibits a bacterium’s ability to build a cell wall. Other antibiotics prevent bacteria from replicating their DNA or building proteins by blocking the various bacterial machinery needed to perform such tasks (Genetic Science Learning Center, “What is an Antibiotic,” 08.15.2014). These techniques are effective at reducing the infection to a level where the patient’s immune system can take over. Though this sounds like a flawless system, bacteria evolve and adapt to survive in spite of these drugs.
Bacteria pick up mutations, or random changes in their genetic makeup, and this occurs whenever they divide. In order to divide, all DNA in the mother cell must be replicated and the main enzyme responsible for this process is DNA polymerase. Polymerase binds together nucleotides, each containing one of the four bases (A, G, C and T) to make new copies of DNA for the daughter cells. However, polymerase makes some mistakes and lays down the wrong base approximately one in every one million to 100 million times (Federation of European Microbiological Societies, “DNA replication fidelity in Escherichia coli: a multi-DNA polymerase affair,” (04.05.2012).
This might not seem very often, but keep in mind that bacterial cells are dividing quite rapidly, which means these mutations are still relevant; Bacteria in a colony may be slightly different than their neighbors. Some of these mutations may provide bacteria with an ability to resist an antibiotic. For example, if the gene encoding a protein that an antibiotic blocks mutates, perhaps the protein would be unaffected by the drug and then able to complete its function.
In addition to these mutations, bacteria can actually harvest useful genes from each other and they achieve this by exchanging DNA plasmids, which are circular strands of DNA that contain a small set of genes that could help a bacteria survive. In a process called conjugation, one bacteria will siphon a copy of this useful plasmid into another one through a straw-like structure called a pilus (Kenyon College Biology Department, “Bacterial Gene Transfer,” 09.20.2016). Conjugation means that in addition to natural selection for bacteria with an antibiotic resistant mutation, these bacteria can effectively transfer their immunity to others, even if they are different species.
Essentially, through antibiotics, humans introduce selection pressures that, via natural selection, produce bacteria that are resistant to antibiotics. This may seem like a grim reality, but remember that as bacteria continue to develop resistance, researchers find new and more precise antibiotics. The problem that warrants a U.N. meeting, is that humans have accelerated and globalized this resistance process by blatant misuse and overuse of antibiotics.
In an ideal world, antibiotics would be a last-resort solution to a bacterial infection and they would be carefully prescribed to match the pathogen in question, and then properly administered in a way that would prevent lots of resistant surviving bacteria. In reality, 80 percent of all antibiotics, by mass, are used on livestock to combat the often unsanitary and crowded conditions in which they are raised (Scientific American, “Antibiotic Resistant Bacteria and the World’s Peril,” 09.19.2016).
People have also began carelessly using antibiotics as “solutions” to ailments antibiotics are not effective against or not necessary for, such as viral infections, or merely for common colds. These factors can result in “superbugs” that have, through conjugation of plasmids from other types of resistant bacteria, acquired immunity many different antibiotics. Continued misuse of what previously was one of our best tools to cure disease could in fact generate a pathogen that humanity would not have a solution for. The U.N. needs to take the lead on setting up policies that can prevent such irresponsible antibiotic use. Since many resistant bacteria are excreted by animals and humans alike, wastewater and sewage treatment practices must improve to prevent the formation of superbugs in these immune bacteria cesspools. Researchers, lawmakers and citizens all need to work together to adequately respond to the threat of antimicrobial resistance.