TABLE 4.

Antimicrobial susceptibility testing results

AntimicrobialAll isolates tested (n = 1,978)USA100 isolates (n = 1,062)USA100 isolates (n = 1,062)USA300 isolates (n = 625)
% in categoryMIC rangeMIC50MIC90% in categoryMIC rangeMIC50MIC90% in categoryMIC rangeMIC50MIC90
SIRSIRSIR
Chloramphenicol57.042.60.4<2->3281630.069.40.6<2->32161697.03.00.04-1688
Clindamycinb36.80.063.2≤0.25->16≤0.25≥161.20.099.9≤0.25->16≥16≥1691.00.09.0≤0.25->16≤0.25≤0.25
Erythromycin5.60.593.9≤0.25->8>8>80.50.499.20.5->8>8>85.60.593.9≤0.25->8>8>8
Daptomycin99.60.00.4a≤0.5-4≤0.5199.40.00.6a≤0.5-4≤0.5199.70.00.3a≤0.5-4≤0.51
Doxycycline98.31.70.1≤1-16≤1≤199.20.80.0≤1-8≤1≤199.50.50.0≤1-8≤1≤1
Tetracycline94.00.15.9≤1->16≤1≤198.20.01.8≤1->16≤1≤189.90.010.1≤1->16≤1>16
Gentamicin95.80.14.1≤2->32≤2≤296.30.03.7≤2->32≤2≤298.70.21.1≤2->32≤2≤2
Levofloxacin18.50.281.3≤0.5->16>16>160.20.099.8≤1-844100.00.00.0≤1-424
Linezolid99.90.00.1a≤1-82499.90.00.1a<4->128<4<4<4->128<4<4
Mupirocinc<4->128<4<4≤0.5->8≤0.5≤0.597.31.01.8≤0.5->8≤0.5≤0.5
Rifampin97.30.71.9≤0.5->8≤0.5≤0.597.20.82.1≤0.5/9.5->8/152≤0.5/9.5≤0.5/9.599.40.00.6≤0.5/9.5->8/152≤0.5/9.5≤0.5/9.5
Trimethoprim- sulfamethoxazole94.50.05.5≤0.5/9.5->8/152≤0.5/9.5≤0.5/9.598.70.01.3
Vancomycin99.90.10.0≤0.5-41199.90.00.1≤0.5-411100.00.00.0≤0.5-211
  • a For daptomycin and linezolid, these isolates are nonsusceptible.

  • b Resistant isolates include those with inducible clindamycin resistance: 17.3% (n = 342) of all isolates, 25.8% (n = 274) of USA100 isolates, and 2.7% (n = 17) of USA300 isolates.

  • c CLSI breakpoints have not been established for mupirocin.