A novel methicillin-resistance cassette in community-acquired methicillin-resistant Staphylococcus aureus isolates of diverse genetic backgrounds.
Until recently, it has been unclear whether community-acquired (CA) methicillin-resistant Staphylococcus aureus (MRSA) isolates represent the spread of hospital MRSA isolates into the community. In 2 CA-MRSA isolates, a novel genetic element, designated staphylococcal cassette chromosome mec (SCCmec) type IV, was found; it differs from SCCmec types I-III in its small size and absence of non-beta-lactam genetic-resistance determinants. To study the prevalence of type IV SCCmec, polymerase chain reaction characterization of SCCmec was performed on DNA from 12 CA-MRSA isolates. The 12 CA-MRSA isolates were from diverse genetic backgrounds, as evidenced by their stratification into 5 pulsed-field gel electrophoresis types, 4 coagulase types, and 2 ribotypes. Eleven of the 12 isolates contained the novel SCCmec type IV element. Ten were resistant only to beta-lactam antibiotics. SCCmec type IV is present on the genome of CA-MRSA isolates. Its relatively small size and presence in isolates of diverse genetic backgrounds suggest that it may spread among S. aureus isolates.
Daum
Robert S
RS
Department of Pediatrics, University of Chicago, Chicago, Illinois 60637, USA. rdaum@peds.bsd.uchicago.edu
Ito
Teruyo
T
Hiramatsu
Keiichi
K
Hussain
Farid
F
Mongkolrattanothai
Kanokporn
K
Jamklang
Mantana
M
Boyle-Vavra
Susan
S
D017714:Community-Acquired Infections / Q000635:transmission*; D003428:Cross Infection / Q000635:transmission; D006801:Humans; D016106:Methicillin Resistance / Q000235:genetics*; D016133:Polymerase Chain Reaction; D013203:Staphylococcal Infections / Q000635:transmission*; D013211:Staphylococcus aureus / Q000145:classification / Q000187:drug effects / Q000235:genetics*