Phenotypic switching of antibiotic resistance circumvents permanent costs in Staphylococcus aureus

Ruth C. Massey*, Angus Buckling, Sharon J. Peacock

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

100 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)1810-1814
Number of pages5
JournalCurrent Biology
Issue number22
Publication statusPublished - 13 Nov 2001
Externally publishedYes

Bibliographical note

Funding Information:
We would like to thank Professor R. Moxon and Drs. C. Tang, C. Bayliss, and N. Day for helpful comments during the preparation of this manuscript. This project was supported by Wellcome Trust grant 009917.


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