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Phenotypic switching of antibiotic resistance circumvents permanent costs inStaphylococcus aureus

Authors
Journal
Current Biology
0960-9822
Publisher
Elsevier
Publication Date
Volume
11
Issue
22
Identifiers
DOI: 10.1016/s0960-9822(01)00507-3

Abstract

Abstract Bacterial antibiotic resistance is often associated with a fitness cost in the absence of the antibiotic [1, 2]. We have examined a resistance mechanism in Staphylococcus aureus that negates these costs. Exposure to gentamicin both in vitro and in vivo has been reported to result in the emergence of a gentamicin-resistant small colony variant (SCV) [3–8]. We show that the emergence of SCVs following exposure to gentamicin results from a rapid switch and that bacteria exposed to cycles of gentamicin followed by antibiotic-free medium repeatedly switched between a resistant SCV and a sensitive parental phenotype (revertants). The fitness of revertants relative to S. aureus with stable gentamicin resistance was greater in drug-free media, which suggests that S. aureus has evolved an inducible and reversible resistance mechanism that circumvents a permanent cost to fitness.

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