Bacteria with Antibiotic Resistance Mutations Reproduce Faster than Non-mutated Bacteria

A team of researchers has recently discovered that bacteria reproduce rapidly when exposed to antibiotics. This allows the bacterial colony to develop mutations for antibiotic resistance faster, speeding up evolution. The details are in a paper that was just published in the journal Nature Ecology & Evolution.

Antibiotic resistance is a growing problem that can be incredibly harmful to people with bacterial infections. When bacteria develop a resistance to modern drugs, doctors are left with fewer options for treating their patients. In some cases, bacteria become immune to all common antibiotics and these strains are a serious public health risk. Scientists have frequently studied the evolution of antibiotic resistance in an attempt to solve the problem.

Scientists from the University of Exeter utilized funding from the Engineering and Physical Sciences Research Council (EPSRC) to study how Escherichia coli bacteria develop resistance to antibiotics. The E.coli strain used in the study is harmful to humans, causing symptoms such as severe diarrhea and kidney failure. The team exposed the bacteria to doxycycline, one of the most common antibiotics for treating bacterial infections. The E.coli bacteria were exposed for four days while the researchers measured how quickly they developed mutations for doxycycline resistance. As expected, the bacteria quickly developed these types of mutations. However, the researchers noticed something that they didn’t expect; the bacteria containing the mutations were multiplying faster than non-mutated bacteria. They were reproducing so quickly that their population tripled within the four days of antibiotic exposure. This rapid evolution continued even after the researchers stopped dosing the population with the antibiotics.

The research team’s findings show that bacteria are capable of reproducing quickly when they gain antibiotic resistance mutations, even after they’re no longer exposed to the drug. Once they develop these mutations, they can focus their energy on reproduction instead of survival. The authors note that according to their findings, it’s important to begin antibiotic treatments immediately to avoid this rapid evolution.


Reding-Roman et al. The unconstrained evolution of fast and efficient antibiotic-resistant bacterial genomes. Nature Ecology & Evolution (2017).

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