Action of Penicillin
The antibiotic drug penicillin acts by binding to the penicillin-binding protein (PBP) on the cell wall of gram-positive bacteria (Romaniuk & Cegelski, 2015). The protein facilitates the formation and strengthening of the cell wall, which is necessary for maintaining the shape, structure, and integrity of the bacteria (Romaniuk & Cegelski, 2015). Once penicillin binds to this protein, this functionality is inhibited thereby leading to a loose cell wall and final disintegration of the bacteria (Romaniuk & Cegelski, 2015). Therefore, the action is only possible in the process of a matching binding surface. The surface of bacteria and virus vary due to their unique compositions. Therefore, penicillin cannot bind to a virus to achieve the same result.
Natural Selection and the Process of Evolution
Natural selection is facilitated by an increase in the population of a given species or bacteria and limited resources. Due to the insufficient resources, bacteria compete for the available resource, which is accompanied by the death of those whose genes cannot favor them to compete favorably (Burch, n.d). The gene variation results from the difference in parentage or vertically transmitted gene which is a matter of chance; one individual can pick either advantageous or disadvantageous genes (Burch, n.d). Other adverse environmental factors may result in natural selection among bacteria. For example, the use of antibiotics provides the pressure necessary for natural selection. Bacteria develop an active pumping mechanism, which expels the antibiotics to the external environment or modifies the antibiotics in a way that it cannot be harmful or modifies its cell wall so that the bacteria cannot bind to it (Burch, n.d; CDC, 2017).
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Resulting Change in the Population after Antibiotic Selection
Continuous use of antibiotics results in the death of bacteria whose phenotypic characteristics do not favor them to resist the antibiotics while those whose phenotypic traits favor them survive. This is a directional selection since one phenotype is favored over another (Frankham, Briscoe & Ballou, 2002).
Commensal Bacteria
Commensal bacteria are bacteria that coexist in a symbiotic relationship with other organisms such as human beings. As they draw nutrients and other benefits from human beings, they provide other services such as crowding out other pathogenic bacteria (Burch, n.d). Antibiotic metabolites are often released from the body to the skin surface or transported within the body when the commensal bacteria encounter these antibiotics; they are likely to develop resistance to the drugs. The genetic disposition causing this effect can then be transmitted to pathogenic bacteria through horizontal gene transfer methods such as transduction, transformation, conjugation and binary fission (Burch, n.d).
Regulating the Spread of Antibiotic Resistance
In order to regulate the spread of antibiotic resistance, it is important to regulate or prevent the formation or evolution of antibiotic-resistant bacteria. As noted earlier on, the process of natural selection requires pressure, which is often supplied by antibiotics. Thus, as antibiotics and other antimicrobial agents are used, the susceptible bacteria die living behind those that are resistant to the drugs. Once this class is established, they can pass their resistance gene to pathogenic strains. Thus, the best approach is to avoid the use of excessive antibiotics and antimicrobials (Burch, n.d; CDC, 2017).
Approach to Stop the Spread of Antibiotic-Resistant Bacteria
Optimizing therapeutic regimens : Longer regimens are necessary for ensuring a good recovery from infection, some last four days, research has indicated that even shorter regimens are as effective as longer ones (Ventola, 2015). This implies that drugs are often given in excess, which further advances the process of natural selection. Reducing the regimen to requisite amount would reduce the rate of antibiotic resistance.
References
Burch, C. (n.d). MRSA and the spread of antibiotic resistance. Retrieved from https://www.youtube.com/watch?v=GBPQL6NcsiM
CDC (2017). Antibiotic Resistance Questions and Answers . Retrieved from https://www.cdc.gov/antibiotic-use/community/about/antibiotic-resistance-faqs.html
Frankham, R., Briscoe, D. A., & Ballou, J. D. (2002). Introduction to conservation genetics. Cambridge University Press.
Romaniuk, J. A., & Cegelski, L. (2015). Bacterial cell wall composition and the influence of antibiotics by cell-wall and whole-cell NMR. Phil. Trans. R. Soc. B, 370 (1679), 20150024.
Ventola, C. L. (2015). The antibiotic resistance crisis: part 2: management strategies and new agents. Pharmacy and Therapeutics, 40(5), 344.
