Affiliation:
1. Programme for Microbiology, Department of Cell and Molecular Biology, Box 596, Biomedical Center, Uppsala University, 751 24 Uppsala, Sweden
Abstract
ABSTRACT
Small-colony variants (SCVs) of
Staphylococcus aureus
are a slow-growing subpopulation whose phenotypes can include resistance to aminoglycosides, defects in electron transport, and enhanced persistence in mammalian cells. Here we show that a subset of mutants selected as SCVs by reduced susceptibility to aminoglycosides are resistant to the antibiotic fusidic acid (FA) and conversely that a subset of mutants selected for resistance to FA are SCVs. Mutation analysis reveals different genetic classes of FA-resistant SCVs. One class, FusA-SCVs, have amino acid substitution mutations in the ribosomal translocase EF-G different from those found in classic FusA mutants. Most of these mutations are located in structural domain V of EF-G, but some are in domain I or III. FusA-SCVs are auxotrophic for hemin. A second class of FA-resistant SCVs carry mutations in
rplF
, coding for ribosomal protein L6, and are designated as FusE mutants. FusE mutants fall into two phenotypic groups: one auxotrophic for hemin and the other auxotrophic for menadione. Accordingly, we have identified new genetic and phenotypic classes of FA-resistant mutants and clarified the genetic basis of a subset of
S. aureus
SCV mutants. A clinical implication of these data is that FA resistance could be selected by antimicrobial agents other than FA.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Pharmacology (medical),Pharmacology
Cited by
83 articles.
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