Affiliation:
1. Departments of Medicine and Microbiology/Immunology, Virginia Commonwealth University School of Medicine, 1101 East Marshall Street, Richmond, Virginia 23298
2. Public Health Research Institute, 225 Warren Street, Newark, New Jersey 07103
Abstract
ABSTRACT
Staphylococcus aureus
becomes resistant to methicillin by acquiring a genomic island, known as staphylococcal chromosome cassette
mec
(SCC
mec
), which contains the methicillin resistance determinant,
mecA
. SCC
mec
is site-specifically integrated into the staphylococcal chromosome at a locus known as the SCC
mec
attachment site (
attB
). In an effort to gain a better understanding of the potential that methicillin-sensitive
S. aureus
(MSSA) isolates have for acquiring SCC
mec
, the nucleotide sequences of
attB
and surrounding DNA regions were examined in a diverse collection of 42 MSSA isolates. The chromosomal region surrounding
attB
varied among the isolates studied and appears to be a common insertion point for acquired foreign DNA. Insertions of up to 15.1 kb were found containing open reading frames with homology to enterotoxin genes, restriction-modification systems, transposases, and several sequences that have not been previously described in staphylococci. Two groups, containing eight and four isolates, had sequences found in known SCC
mec
elements, suggesting SCC
mec
elements may have evolved through repeated DNA insertions at this locus. In addition, the
attB
sequences of the majority of MSSA isolates in this collection differ from the
attB
sequences of strains for which integrase-mediated SCC
mec
insertion or excision has been demonstrated, suggesting that some
S. aureus
isolates may lack the ability to site-specifically integrate SCC
me
c into their chromosomes.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
81 articles.
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