Table 2.
Description of the two SCCmec IVa structures (A and B) detected by PCR mappinga
| SCCmec IVa variant | Strain used as referenceb |
spa type(s) (no. of strains) |
ccr allotype | ACME gened |
PVL | Profile according to PCRs 1 to 9 | ||
|---|---|---|---|---|---|---|---|---|
| CC8 | Other CCc | arcA | opp3AB | |||||
| A1 | MW2 | t008 (2), t064 (2) | ccrAB2 | 0 | 0 | 1/0e | 0 0 0 0 1 1 0 0 0 | |
| A2 | FPR3757 | t008 (23), t068 (1), t121 (1), t211 (1), t3980 (1), t5098 (1) | ccrAB2 | 1 | 1 | 1/0e | 0 0 0 0 1 1 0 0 0 | |
| B1 | M1 | t024 (17), t430 (3), t351 (1), t842 (1), t2555 (1) | t012 (1) | ccrAB2 and ccrAB4 | 1 | 0 | 0 | 1 1 1 1 1 0 0 0 0 |
| B2 | M299 | t024 (11) | ccrAB2 | 0 | 0 | 0 | 0 0 0 1 1 0 1 0 0 | |
| B3 | M15 | t024 (16), t430 (1), t846 (1) | t127 (1) | ccrAB2 | 1 | 0 | 0 | 0 0 1 1 1 0 0 1 0 |
| B4 | M1298 | t024 (2) | ccrAB2 and ccrAB4 | 0 | 0 | 0 | 1 0 0 1 1 0 0 0 1 | |
| B5 | M289 | t979 (1) | ccrAB2 | 1 | 0 | 0 | 0 0 1 1 1 0 0 0 0 | |
| NT1f | M620 | t024 (3) | ccrAB2 | 0 | 0 | 0 | 1 0 0 0 1 0 0 0 0 | |
| NT2f | M220 | t024 (1), t064 (1) | ccrAB2 | 0 | 0 | 0 | 0 0 0 0 1 0 0 0 0 | |
A1 and A2 correspond to the prototype SCCmec IVa cassette and the ACME I-positive variant associated with USA300, respectively. B1 and B2 were described recently (2), and B3, B4, and B5 are novel variants identified in this study.
MW2 and FPR3757, isolated in Japan and in the United States, respectively, were kindly provided by T. Ito. The remaining standards were Danish clinical MRSA isolates from Hvidovre Hospital, Hvidovre, Denmark.
spa types not associated with CC8: t012 (CC30), t127 (CC1), and t979 (CC5).
Possession of both arcA and opp3AB suggests the presence of ACME I, which is typical of the S. aureus USA300 lineage. Possession of only arcA suggests the presence of the recently described ACME II variant ΨSCCarc (2).
50% and 83% of the isolates with variants A1 and A2 were PVL positive, respectively.
Isolates without any apparent loci in J3 were considered nontypeable (NT1 and NT2).