Bacteria and Antibiotics
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
Click here to return to the Molecular Biology Archives
Update: June 2012