Imperial College London


Faculty of MedicineDepartment of Medicine

Non-Clinical Lecturer in Molecular Microbiology



a.edwards Website




5.40AFlowers buildingSouth Kensington Campus






BibTex format

author = {Edwards, AM},
journal = {Journal of Bacteriology},
title = {Phenotype-switching is a natural consequence of Staphylococcus aureus replication},
year = {2012}

RIS format (EndNote, RefMan)

AB - The pathogen Staphylococcus aureus undergoes phenotype-switching in vivo from its normal colony phenotype (NCP) to a slow-growing, antibiotic-resistant small colony variant (SCV) phenotype, which is associated with persistence in host cells and tissues. However, it is not clear whether phenotype-switching is the result of a constitutive process that is selected for under certain conditions, or is triggered by particular environmental stimuli. Examination of cultures of diverse S. aureus strains in the absence of selective pressure consistently revealed a small gentamicin-resistant SCV sub-population, which emerged during exponential-phase NCP growth and increased in number until NCP stationary phase. Treatment of replicating bacteria with the antibiotic gentamicin, which inhibited NCP but not SCV replication, resulted in an initial decrease in SCV numbers, demonstrating that SCVs arise as a consequence of NCP replication. However, SCV population expansion in the presence of gentamicin was re-established by selection of phenotype-stable SCVs and subsequent SCV replication. In the absence of selective pressure however, phenotype-switching was bi-directional and occurred at a high frequency during NCP replication, resulting in SCV turnover. In summary, these data demonstrate that S. aureus phenotype-switching occurs via a constitutive mechanism that generates a dynamic, antibiotic-resistant sub-population of bacteria that can revert to the parental phenotype. The emergence of SCVs can therefore be considered a normal part of the S. aureus life-cycle and provides an insurance policy against exposure to antibiotics that would otherwise eliminate the entire population.
AU - Edwards,AM
PY - 2012///
TI - Phenotype-switching is a natural consequence of Staphylococcus aureus replication
T2 - Journal of Bacteriology
ER -