TABLE 1.
MIC frequency distributions for agents against 4,131 clinical isolates of S. aureus from 43 U.S. medical centers
| Antimicrobial agent | No. of isolates (cumulative %) with indicated MIC (μg/ml) |
I (%)a | R (%)a | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ≤0.12 | 0.25 | 0.5 | 1 | 2 | 4 | 8 | 16 | 32 | ≥64 | |||
| Ceftaroline | 221 (5.4) | 1,814 (49.3) | 1,323 (81.3) | 750 (99.4) | 23 (100) | 0.6 | 0 | |||||
| Clindamycin | 3512 (85.0) | 27 (85.7) | 9 (85.9) | 0 (85.9) | 7 (86.1) | 2 (86.1) | 4 (86.2) | 2 (86.3) | 3 (86.3) | 565b (100) | 0.2 | 13.9c |
| Daptomycin | 42 (1.0) | 2,414 (59.5) | 1,637 (99.1) | 34 (99.9) | 4 (100) | 0.2d | ||||||
| Erythromycin | 19 (0.5) | 564 (14.1) | 859 (34.9) | 127 (38.0) | 14 (38.3) | 13 (38.6) | 23 (39.2) | 73 (41.0) | 203 (45.9) | 2,236b (100) | 3.7 | 61.4 |
| Levofloxacin | 705 (17.1) | 1,725 (58.8) | 141 (62.2) | 33 (63.0) | 10 (63.3) | 560 (76.8) | 292 (83.9) | 140 (78.3) | 81 (89.3) | 444 (100) | 0.2 | 37.3 |
| Linezolid | 1 (0.02) | 2 (0.1) | 48 (1.2) | 2,424 (59.9) | 1,627 (99.3) | 28 (99.9) | 1 (100) | 0.02 | ||||
| Oxacillin | 33 (0.8) | 519 (13.4) | 956 (36.5) | 392 (46.0) | 127 (49.1) | 70 (50.8) | 149 (54.4) | 254 (60.5) | 1,631e (100) | 51 | ||
| Tigecycline | 3004 (72.7) | 980 (96.4) | 131 (99.6) | 16 (100) | 0.4f | |||||||
| Tetracycline | 743 (18.0) | 2,755 (84.7) | 346 (93.1) | 36 (93.9) | 46 (95.0) | 28 (95.7) | 9 (95.9) | 20 (96.4) | 44 (97.5) | 104 (100) | 0.2 | 4.1 |
| TMP-SMX | 3839 (92.9) | 108 (95.6) | 42 (96.6) | 22 (97.1) | 8 (97.3) | 2 (97.3) | 9 (97.6) | 10 (97.8) | 13 (98.1) | 78 (100) | 2.7 | |
| Vancomycin | 1 (0.02) | 431 (10.5) | 3,658 (99.0) | 41 (100) | 0 | 0 | ||||||
a
Intermediate (I) and resistant (R) categories are those defined by CLSI with the exceptions noted below.
b
MIC > 32 μg/ml.
c
An additional 12.7% of isolates were positive for inducible clindamycin resistance.
d
Nonsusceptible, MIC > 1 μg/ml; intermediate and resistant categories not defined by CLSI.
e
MIC > 16 μg/ml.
f
Based on FDA interpretive criterion for susceptibility of ≤0.5 μg/ml.