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Background

Background

 

Identification of the first SCCmec

The SCCmec element carried by preMRSA N315 was characterized first by cloning the chromosomal region surrounding mecA, which was not carried by MSSA strains and was called “mecDNA” or “additional DNA”. Determination of the entire nucleotide sequence and subsequent comparison with the corresponding region of methicillin-susceptible S. aureus strain revealed that the mecDNA has a specific structure for the genetic trait of methicillin resistance (Ito et al. 1999).

(1) It carries the class A mec gene complex, consisting of mecA, its regulatory genes, mecI and mecR1, and the insertion sequence IS431.

(2) It carries two site-specific recombinase homologues.

(3) It has characteristic direct repeats and inverted repeats at both ends.

(4) It is located at the 3’ end of orfX.

Subsequent experiments showed that the island was precisely excised from the N315 chromosome and integrated into the specific site of the N315 chromosome by the function of two site specific recombinases. Thus we named the island staphylococcal cassette chromosome mec (SCCmec) as a new family of staphylococcal genomic islands and its recombinases as cassette chromosome recombinases A and B (ccrA and B) (Katayama et al. 2001.)


Lists of strains of which SCCmec elements have been characterized

 

SCCmec-sequenced strains

・N315 (isolated in Japan in 1981) Ito et al. 1999
・NCTC10442 (isolated in England in 1961) Ito et al. 2001
・85/2082 (isolated in New Zealand in 1985) Ito et al. 2001
・HDE288 (isolated in Portugal in 1996) Oliveira et al. 2001
・CA05 (isolated in USA in 1999) Ma et al. 2002
・8/6-3P (isolated in USA in 1996) Ma et al. 2002
・WIS (isolated in Australia in 1995) Ito et. al. 2004
・AR13.1/330.2 (isolated in Ireland in 1999) Shore et al. 2005
・AR43/3330.1 (isolated in Ireland in 1999) Shore et al. 2005
・M03-68 (isolated in Korea) Kwon et al. 2005
・JCSC3063 (isolated in Japan in 2001) Hisata et al. 2005
・JSGH17 (isolated in Taiwan in 1997-2002) Boyle-Vavra  et al. 2005
・ZH47 (isolated in Switzerland in 2003) Heusser R et al. 2007
・P1 (isolated in Taiwan in 2000-2006) Takano et al. 2008

 

Genome sequenced strains carrying SCCmec elements

・N315 (isolated in Japan in 1981) Kuroda et al. 2001
・Mu50 (isolated in Japan in 1996) Kuroda et al. 2001
・MW2 (isolated in USA in 1998) Baba et al. 2002
・MRSA252 (isolated in UK in 1997) Holden et al. 2004
・COL (isolated in UK in the early 1960s) Gill et al. 2005
・RP62A (isolated in USA in 1979-1980) Gill et al. 2005
・FPR3757 (isolated in USA) Diep et al. 2006
・JH1 (isolated in USA) Mwangi MM et al. 2007
・JH9 (isolated in USA) Mwangi MM et al. 2007