In the 1960s, it was common practice to prescribe multiple antibiotics to fight

Question

In the 1960s, it was common practice to prescribe multiple antibiotics to fight bacterial infections. It is. also, often the case that patients do not take the entire "course" of the antibiotics. Antibiotic genes are often found on conjugative plasmids. How do these factors affect the evolution of antibiotic resistance and of resistance to multiple antibiotics in particular? Compare and contrast the effects of mutation, migration, genetic drift, and natural selection on genetic variation What physical features of Galapagos made possible the evolution of Darwin finches?

Explanation / Answer

Ques-1:

Early in the discovery (mid 1900’s) of antibiotics drug resistance occurred within a few years of the introduction of new antibiotics because the "resistance mechanisms to these drugs was not already in bacterial populations". This is because antibiotics use has induced "selective pressure" in bacterial populations & leading to death of some unfit bacteria finally, those bacteria, which can withstand to the antibiotic, have grown. In lysogeny phase bacteriophages, DNA incorporated into the bacterial chromosome and become prophase. In this process, there are no lyses of the bacterial cell. R- Factor encode for multidrug resistance also can be transferred through conjugation from one bacterium to another bacterium.

Normally, the discrete genetic elements of pathogens such as bacteriophages, prokaryotic transposons & conjugate plasmids that integrated into the host cell genome via horizontal gene transfer finally become more recombinant to generate virulence of pathogen. The hypothesis of this phenomenon is to acquire higher resistance towards host defense system by increasing “pathogen virulence factor synthesis”. Bacteria generate genetic diversity due to presence of abnormal genome followed by horizontal transfer genetic material at the time of conjugation, transformation and transduction through extra circular plasmid to other cells. Sexual reproduction of prokaryotes is through conjugation imparts genetic diversity to “resist extreme host cell environment including temperature and PH”. Antibiotic drug resistant genes are transferred from bacteria to another bacteria through horizontal gene transfer finally to produce more resistant cell wall enzyme via gene expression or sometimes these genes are going to code for "proteins" that inactivate multiple antibiotics, as an evolutionary adaptation to harsh environment. Therefore, these evolutionary adaptations are going to be produced in bacteria by genetic variation to resist multiple antibiotics (since 1960). This is due to quorum sensing (a type of bacterial communication) and presence of diversified genes finally propagating those genes via horozontal gene transfer of conjugate plasmids

For example:

The perfect conditions to breed for antibiotic resistance are external environment & wastewater sewage treatment plants where we can find more human colifroms commensuals, pathogenic prokaryotes, in which low levels of antibiotics such as penicillins, tetracyclines or high levels of antibiotics quinolones etc are given to examine the "bacteria acquiring antibiotic resistance". Therefore, these conditions are more suitable because of type I mating pair-forming system (MPFI) & horizontal gene transfer (as described below) followed by MOBP relaxase, and insertion sequence transposon to promote breed for antibiotic resistance even under Low levels or high levels of antibiotics. Therefore, it has clearly illustrated that these ideal conditions are responsible for the development of naturally adaptive genes via convergent evolution of resistance genes in pathogenic bacteria.

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