Structural comparison of three types of staphylococcal cassette chromosome mec integrated in the chromosome in methicillin-resistant Staphylococcus aureus.
The beta-lactam resistance gene mecA of Staphylococcus aureus is carried by a novel mobile genetic element, designated staphylococcal cassette chromosome mec (SCCmec), identified in the chromosome of a Japanese methicillin-resistant S. aureus (MRSA) strain. We now report identification of two additional types of mecA-carrying genetic elements found in the MRSA strains isolated in other countries of the world. There were substantial differences in the size and nucleotide sequences between the elements and the SCCmec. However, new elements shared the chromosomal integration site with the SCCmec. Structural analysis of the new elements revealed that they possessed all of the salient features of the SCCmec: conserved terminal inverted repeats and direct repeats at the integration junction points, conserved genetic organization around the mecA gene, and the presence of cassette chromosome recombinase (ccr) genes responsible for the movements of SCCmec. The elements, therefore, were considered to comprise the SCCmec family of staphylococcal mobile genetic elements together with the previously identified SCCmec. Among 38 epidemic MRSA strains isolated in 20 countries, 34 were shown to possess one of the three typical SCCmec elements on the chromosome. Our findings indicated that there are at least three distinct MRSA clones in the world with different types of SCCmec in their chromosome.
Ito
T
T
Department of Bacteriology, Juntendo University, Tokyo 113-8421, Japan.
Katayama
Y
Y
Asada
K
K
Mori
N
N
Tsutsumimoto
K
K
Tiensasitorn
C
C
Hiramatsu
K
K
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D002876:Chromosomes, Bacterial; D019143:Evolution, Molecular; D006602:Hexosyltransferases; D006801:Humans; D016106:Methicillin Resistance / Q000235:genetics*; D008969:Molecular Sequence Data; D002267:Muramoylpentapeptide Carboxypeptidase / Q000235:genetics*; D016254:Mutagenesis, Insertional; D046915:Penicillin-Binding Proteins; D010458:Peptidyl Transferases; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000235:genetics; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D013211:Staphylococcus aureus / Q000235:genetics*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D046915:Penicillin-Binding Proteins; D010940:Plant Proteins; C090420:ccr protein, Citrus x paradisi; D010458:Peptidyl Transferases; D006602:Hexosyltransferases; D002267:Muramoylpentapeptide Carboxypeptidase