On pg. 117-123, Dr. Moalem describes how bacteria have changed over time to resist stronger antibiotics and draws references from the work of Paul Ewald to explain the idea of the virulence of an organism. This relates to Big Idea 1: The process of evolution drives the diversity and unity of life because antibiotics might actually be harming people by creating stronger bacteria through natural selection.
Use the historical context provided on pg. 117 about penicillin to explain why Dr. Moalem refers to antibiotics as an "arms race"; be sure to address how evolution and natural selection play a role and what advantages the bacteria have. Next, summarize what the virulence of an organism is and identify and explain what Ewald thinks causes various levels of virulence among different organisms by referring to two specific organisms analyzed in the text. Finally, relate Ewald's findings to evolution in the antibiotics arms race, and explain how Dr. Moalem uses his findings to hypothesize how we can overcome the antibiotics arms race; also research what are some current methods to fight bacteria that are in line with his hypothesis.
(Posted by Raymon Cao, racao4@students.d125.org)
Dr. Moalem uses the word arm race because whenever new antibiotics are introduced or discovered, bacteria always develops the resistance for the new antibiotic within very short amount of time; when Dr. Alexander Fleming discovered penicillin,the first antibiotic, in 1928, no bacteria had resistance for penicillin. However, in 1950, almost 40 percent of bacteria was penicillin-resistant.
ReplyDeleteThis is caused by the rapid mutation rate of the bacteria, and since it is more beneficial for them to mutate very quickly to respond to the outside selection pressure so that they can reproduce and survive. Therefore, since the antibiotics is the extreme toxins for the bacteria, it is beneficial for them to build a resistance toward the antibiotic so that they can survive and reproduce under such frequent presence of antibiotics. this is deeply related to the Big Idea 1 about the evolution and how the organisms are adapted to survive in the environment, and Big Idea 3, the response of organisms to the outside environment. Bacteria will respond to the outside toxins by developing the resistance through rapid mutations and quick divisions (binary fission). In the book Survival of the Sickest page 117, the various example of history of resistance protein is displayed, and he says "all of this sounds frightening — as if we're in an arm race where the other side has vastly superior technology." He expresses his amazed feeling of the speed of bacteria to build up resistance as the antibiotics become more and more common in the world. Even in the CDC article, the fear of resistance is represented for the Americans (http://www.cdc.gov/features/antibioticresistance/).
The virulence is the degree of how the parasites (viruses, bacteria, any pathogens we can think of) harm their hosts. In this scenario, the virulence of Cholera and common cold is discussed; since Cholera will be transmitted through the oral contact or faeces, the virulence will be very severe since the survival of host is not required for the Cholera bacteria to survive and find different hosts. The common cold is the opposite; since the common cold virus requires the close contact of hosts (humans) thus the virulence is very low compared to other deadly viruses. The virulence of the parasites or pathogens is dependent on its mode of transmittance of the disease. Thus, the mode of transmittance will indicate the evolutionally optimal virulence for the pathogens, and if we block the transmittance of the organisms (for example, in the example of Cholera, people could eliminate the bacteria by improving the sewage system to provide us with clean water). Cleaning out the viruses (or any pathogens) after they were rejected form the patients will be the main way to prevent the future epidemic and this will be much more effective than keep using antibiotics, which can be effective but not a sustainable solutions to the diseases, and Dr. Moalem encourages us to create a sustainable solutions like one which is already presented to treat and prevent the disease transmittance.
— Makoto Seita (e-mail: mseita3@students.d125.org)