Darwinism and the Antibiotic Age: What is the Price of Survival? (6)

Darwinism and the Antibiotic Age: What is the Price of Survival? (6) Bacteria are not infinitely resilient, they cannot be exposed to these mutations that negatively affect their function without having this effect on their ability to reproduce. Yes, bacteria’s ability to reproduce is often impaired by these mutations. Bacteria have even experienced very strong selective pressure during their exposure to antibiotics, so they have no choice but to completely destroy or survive while paying the price of survival. We can monitor this biological cost in the fitness of resistant strains by relaxing the selective pressure from the bacteria; i.e., eliminating the antibiotic from the environment surrounding the bacteria, in which case we note the low speed of reproduction of resistant strains compared to their non-resistant ancestors, and in the struggle between the two types we find that the non-resistant species triumphs and overwhelms the resistant type, this observation opens the door for specialists to develop new strategies to combat species that have gained resistance by exploiting this lack of vital fitness. Not all mutations that cause bacteria to become resistant to antibiotics also cause them to decrease their fitness significantly, and they see this claim as a kind of exaggeration. They see that bacteria can avoid the price that they pay in terms of fitness through certain compensatory mutations. A lot of scientific papers take the concept of fitness cost seriously, because an accurate understanding of the nature of that cost is necessary to help scientists know if resistance will continue to spread, and this is confirmed by Anderson's paper, where he says: "The biological cost of resistance may predict the risk of the development of resistance" (1), meaning that biological cost may be an indicator of the likelihood of the emergence and spread of resistance. The importance of the biological cost concept is emphasized by Linus Sandergen's research group paper in the journal Antimicrobial resistance, entitled "The mechanism of resistance to nitrofurantoin, and the cost of fitness in Escherichia coli bacteria", where the paper notes that "the biological cost of antibiotics is a critical factor in determining the rate of emergence and spread of resistant strains". Anderson points out the importance of understanding the cost of fitness to see if resistant strains will persist after stress relaxation: "The cost of resistance to resistance is a key factor influencing the rate and course of development of antibiotic resistance. Recent studies have shown that antibiotic resistance, whether due to target modification or other mechanisms, often causes a lack of fitness expressed as a decrease in growth rate, virulence, or transmission. We can then use that knowledge to select and design targets and medicines where cost is highest and potential compensation lowest.” Contrary to what evolution predicts, bacteria descend to less complex forms rather than to more complex forms with more information and functions, and the resistance they gain in this way cannot be maintained if the pressure that was almost eliminated is relaxed, which means it is a transient phenomenon, and Darwinian evolution has nothing to do with it. (1) Dan I Andersson, “The biological cost of mutational antibiotic resistance: any practical conclusions?,” Current Opinion in Microbiology, Vol. 9:461–465 (2006). (2) Linus Sandegren, Anton Lindqvist, Gunnar Kahlmeter, and Dan I. Andersson, “Nitrofurantoin resistance mechanism and fitness cost in Escherichia coli,” Journal of Antimicrobial Chemotherapy, Vol. 62, 495–503 (2008). - Management of the Brahin Center — Source: Brahin Center website - Posted on 2018-01-19 (archived at the Internet Archive) https://braheen.com/articles/evolution-design/الداروينية-وعصر-المضادات-الحيوية-ما-هو-ثمن-البقاء؟-6