Let's say penicillin can kill the bacteria. After using it for 10 years, the bacteria developed resistance to penicillin, so no one is using penicillin anymore because it has no effect. After 15 years, reports have found that most of the bacteria loss the penicillin resistant trait.
If the doctors start prescribing penicillin to fight the bacteria again, would you expect penicillin resistant to evolve faster, about the same time, or slower than the first time they developed resistance, which was 15 years?
***I thought it would be faster for those bacteria in the population that used to develop resistance in the past and about the same time for those bacteria that are never treated with penicillin before. This is just my instinct, correlating that to how the human immune system is operating.
1 answer
faster. There probably were several genes involved in the resistance, and when it lost the resistance, chances are that most are still present.