April 22, 2014
Evolutionary Biology 451
Evolution of Microbial Resistance
Antimicrobial resistance is the ability of a microorganism to withstand the effects of an antibiotic drug in which it was originally sensitive to. Resistant organisms are able to withstand attack by antimicrobial drugs such as antibiotics, antifungals, and antivirals which makes standard treatment procedures ineffective. Antimicrobial resistance is something that has evolved naturally via natural selection through random mutations, it can also be achieved by applying an evolutionary stress on a population. Once a gene mutation is generated, bacteria can then transfer genetic information horizontally, between individuals, by plasmid exchange. When a microorganism carries multiple resistance genes, it is termed multiresistant, these multiresistant bacteria have come to be known as superbugs. It is also possible for antibiotic resistance to be introduced artificially into a microorganism through transformation protocols. Still the main reason for increased antibiotic resistance is because of evolution via natural selection, where we see the microorganism reacting to an environmental pressure, the antibiotic. The bacteria which have formed the mutation, allowing them to survive, will then live on and reproduce. We then find that the mutated trait for resistance is passed on to their offspring, which leads to a fully resistant generation for that specific antibiotic.
Antimicrobial resistance is a large cause for concern globally for many reasons, such as increased deaths, lack of control over infectious diseases, increased health care costs, and detrimental effects on trade and global economy. Because infections from resistant microorganisms fail to respond to standard treatments, they tend to result in prolonged illnesses and a higher risk of death. Death rates for patients infected with resistant pathogens are roughly twice than those infected with non-resistant pathogens. These resistant pathogens also lead to an increase in transmission rates, as patients remain infectious for longer periods of time. Another concern for health care officials is the possibility of returning to a pre-antibiotic era, with the risk of some pathogens becoming untreatable and uncontrollable. One reason we see the use of first-line medications, such as penicillin is due to the fact that they are easily made and cheaper to produce. When pathogens become resistant to first-line medications, health care providers are forced to use more expensive therapeutic measures. The longer an illness lasts, the longer the treatment must last as well, increasing health-care costs and putting a bigger economic burden on families and society. Antimicrobial resistance also has an effect on health-care gains to society, as it can limit the success of treatments such as organ transplantation, chemotherapy and major surgeries if antimicrobials are ineffective for care and prevention of infections....