TABLE 2

Molecular characterization of 30 methicillin-resistant Staphylococcus aureus isolates, University of Chicago Medical Center, 1994 to 1997a

PFGE type (80% similarity cutoff)bTotal no. of isolates (%)MLSTSCCmec typePresence of geneYr of acquisitionspa typecNo. of isolates
PVLarcAopp3
NT2 (6.7)8IV+1997NA1
12IV1997NA1
USA1002 (6.7)5II1995NA1
5II1997NA1
USA2003 (10.0)5II1994NA1
5II1995NA1
36II1996NA1
USA3001 (3.3)8II1995t0641
USA40013 (43.3)1IV+1996NA3
1IV+1997NA5
1IV1995NA2
1IV1997NA1
8IV+1997NA1
8IV1994NA1
USA5008 (26.7)8IV+1996t0646
8IV+1997t0642
USA6001 (3.3)45IV1997NA1
Total30 (100)30
  • a PFGE, pulsed-field gel electrophoresis; MLST, multilocus sequence typing; PVL, Panton-Valentine leukocidin; arcA and opp3, markers for the arginine catabolic mobile element (ACME) detected by PCR.

  • b The isolates fell within the standard criteria used for inclusion in the USA typing scheme (at least 80% similarity to the pattern of a particular USA type). NT, nontypeable; the isolate(s) indicated did not fall into one of the known USA type clonal groups. All isolates showed banding patterns by PFGE. If an isolate had >80% pattern similarity with multiple USA types, the USA type that had the highest percentage of similarity was designated as the type.

  • c Only USA300 and USA500 isolates were genotyped using spa typing. NA, not applicable (testing was not conducted).