title: Identification of chromosomal location of mupA gene, encoding low-level mupirocin resistance in staphylococcal isolates.
abstract: Low- and high-level mupirocin resistance have been reported in Staphylococcus aureus. The expression of plasmid-encoded mupA is responsible for high-level mupirocin resistance. Low-level mupirocin-resistant strains do not contain plasmid-encoded mupA, and a chromosomal location for this gene has not previously been reported. We examined high- and low-level mupirocin-resistant S. aureus strains to determine if mupA was present on the chromosome of low-level-resistant isolates. Southern blot analysis of DNA from four mupirocin-resistant strains identified mupA in both high- and low-level mupirocin-resistant strains. Low-level mupirocin-resistant strains contained a copy of mupA on the chromosome, while the high-level mupirocin-resistant isolate contained a copy of the gene on the plasmid. PCR amplification of genomic DNA from each mupirocin-resistant strain resulted in a 1.65-kb fragment, the predicted product from the intragenic mupA primers. This is the first report of a chromosomal location for the mupA gene conferring low-level mupirocin resistance.
authors.affiliation: Division of Infectious Diseases, University of Michigan Medical School, Ann Arbor, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Ramsey
authors.forename: S F
authors.initials: SF
authors.lastname: Bradley
authors.forename: C A
authors.initials: CA
authors.lastname: Kauffman
authors.forename: T M
authors.initials: TM
authors.lastname: Morton
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015139:Blotting, Southern; D002876:Chromosomes, Bacterial / Q000235:genetics*; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D005784:Gene Amplification; D005798:Genes, Bacterial / Q000235:genetics*; D016712:Mupirocin / Q000494:pharmacology; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D016712:Mupirocin