IMAT 2012 Q55 [Antibiotics]

Antibiotics are becoming less effective due to:

A. people becoming immune to them
B. people not finishing the full course
C. new antibiotics being available
D. people becoming resistant to them
E. artificial selection

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The answer to this question is choice B.

Before we discuss the correct answer, let us rule out the other choices:

  • people becoming immune to them.” : The immune system is our body’s defense against foreign intrusions like infections that have the ability to cause disease or other deleterious effects. This is a complex process that involves cells working in unison to achieve the common goal of eradicating the offending agent. Usually, the stimulus that initiates the so called “immune response” is commonly a certain molecule that is is either present within the offending agent, or within their membrane, or even substances that these offending agents secrete, wherein different immune cells have the receptors to sense these substances, and start the cascade of the immune response. Over time, our immune cells will learn to recognize these substances through memory B cells, so that if the infection repeats in the future, the effects on the body will be significantly decreased by our immune system. With that being said, our immune system is not prompted to develop memory B cells to antibiotics, thus our immune system does not have the ability to contribute to decreasing antibiotic efficacy.
  • new antibiotics being available” : The presence of new antibiotics does not play any role in decreasing antibiotic activity. In fact, one of the most significant reasons that prompts the discovery and experimentation with new antibiotics is the development of antibiotic resistance. If the medical community stops developing new antibiotics, the problem of resistance gets even worse.
  • people becoming resistant to them” : It is important to be aware, that antibiotic resistance should be attributed to the infections themselves and not the hosts or the humans. Resistance to these medications are developed by microbes as a form of evasion against antibiotics. Microbes evolve features within themselves or systems that alter the ability of antibiotics to eradicate them in the first place. Thus, this question should not be in your consideration.
  • "artificial selection. : What is artificial selection? This is also commonly known as “selective breeding” and basically, it is when we as humans intervene to preserve a certain trait by controlling factors that would favor offspring that have these favorable traits. Thus just by the definition itself, it would not make much sense that we would artificially control external factors to favor antibiotic resistance, which removes this from your considerations.

Why is choice B correct?

  • By elimination, this is the correct answer, since patients that do not complete their full course of antibiotics do not fully eradicate their infection which can cascade into multi-factorial adverse effects in terms of infection and transmission. It would be useful to imagine the scenario, wherein patients do not eradicate the infection completely by discontinuing or misusing antibiotics, this allows for more transmission to other people, and even provides the opportunity to develop resistance by evolving evasion tactics. The transmitted microbes could also be those those that are already resistant to certain antibiotics, which increases the prevalence of this problem of decreasing antibiotic efficacy.