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Name: TC
Status: Student
Grade:  6-8
Location: PA
Country: United States
Date: August 2005

Can bacteria lose their resistance against antibiotics? If so, how?

As a result of reverse mutation, bacteria can lose their resistance to antibiotics. In fact, if you grow resistant bacteria for many generations in the absence of antibiotic, the bacterial population will eventually lose its antibiotic resistance because wildtype revertants will always have a selective advantage over the resistant mutants. Thats why the wildtype is not resistant to the antibiotic.

Ron Baker, Ph.D.

Yes, they can. Remember that what gives them resistance in the first place is a genetic change that gives them some ability to escape the effect of the antibiotic. Some bacteria for instance can break an important ring structure in penicillin that inactivates it. This is the result of a random change in the DNA of the bacteria. If the DNA randomly changes back, which could happen according to the laws of probability, then the bacteria would be susceptible again.


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