Authors: Jorge Moura de Sousa, Ana Sousa, Catarina Bourgard, and Isabel Gordo
Journal Ref.: Future Microbiol. 10, 1415-1431 (2015).
Aim: To investigate the cost of antibiotic resistance versus the potential for resistant clones to adapt in maintaining polymorphism for resistance.
Materials & methods: Experimental evolution of Escherichia coli carrying different resistance alleles was performed under an environment devoid of antibiotics and evolutionary parameters estimated from their
frequencies along time.
Results & conclusion: Costly resistance mutations were found to coexist with lower cost resistances for hundreds of generations, contrary to the hypothesis that the cost of a resistance dictates its extinction. Estimated evolutionary parameters for the different resistance backgrounds suggest a higher adaptive potential of clones with costly antibiotic resistance mutations, overriding their initial cost of resistance and allowing their maintenance in the absence of drugs.