Effects of Environment on Compensatory Mutations... : Science (original) (raw)

Effects of Environment on Compensatory Mutations to Ameliorate Costs of Antibiotic Resistance

• J. Björkman
• I. Nagaev
• O. G. Berg
• D. Hughes
• D. I. Andersson

Science

287

(

5457

)

:p

1479

-

1482

,

February 25, 2000

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Most types of antibiotic resistance impose a biological cost on bacterial fitness. These costs can be compensated, usually without loss of resistance, by second-site mutations during the evolution of the resistant bacteria in an experimental host or in a laboratory medium. Different fitness-compensating mutations were selected depending on whether the bacteria evolved through serial passage in mice or in a laboratory medium. This difference in mutation spectra was caused by either a growth condition-specific formation or selection of the compensated mutants. These results suggest that bacterial evolution to reduce the costs of antibiotic resistance can take different trajectories within and outside a host.