What causes an­tibi­otic re­sis­tance?

Focus-Science and Technology - - Q&A - ED­DIE FRIEL,

An­tibi­otic re­sis­tance is a good ex­am­ple of nat­u­ral se­lec­tion. Ex­po­sure to an­tibi­otics in­creases se­lec­tive pres­sure in bac­te­rial pop­u­la­tions, boost­ing the per­cent­age of re­sis­tant bac­te­ria, with new bac­te­rial gen­er­a­tions in­her­it­ing re­sis­tance genes. Bac­te­ria can some­times pass on re­sis­tance by shar­ing ge­netic ma­te­rial with each other. They can also be­come re­sis­tant fol­low­ing spon­ta­neous changes to their genes. Some gene mu­ta­tions al­low bac­te­ria to pro­duce en­zymes that in­ac­ti­vate an­tibi­otics. Oth­ers change their outer struc­ture so that an­tibi­otics can’t gain ac­cess. Some bac­te­ria even de­velop pump­ing mech­a­nisms to ex­pel an­tibi­otics. Overuse and mis­use of an­tibi­otics has ex­ac­er­bated the prob­lem of an­tibi­otic re­sis­tance.

Here, the wall of a bac­te­rial cell is ex­pelling an­tibi­otics ( green) via a pump mech­a­nism

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