TABLE 3.
Antimicrobial activities and spectra of linezolid and comparator agents when tested against species and groups of Gram-positive cocci isolated in the United States and submitted to the LEADER Surveillance Program, 2012
| Organism(s), antimicrobial agent (no. of isolates tested [n = 7,429]) | MIC (μg/ml) |
%S/%I/%R by CLSI criteriaa | ||
|---|---|---|---|---|
| MIC50 | MIC90 | Range | ||
| S. aureus isolates | ||||
| Oxacillin resistant (1,443) | ||||
| Linezolid | 1 | 2 | 0.25–4 | 100.0/0.0/0.0 |
| Ciprofloxacin | >4 | >4 | 0.06–>4 | 32.5/1.4/66.1 |
| Clindamycin | ≤0.25 | >2 | ≤0.25–>2 | 74.4/0.2/25.4 (12.3)b |
| Erythromycin | >16 | >16 | ≤0.12–>16 | 9.6/2.0/88.4 |
| Gentamicin | ≤1 | ≤1 | ≤1–>8 | 97.0/0.1/2.9 |
| Trimethoprim-sulfamethoxazole | ≤0.5 | ≤0.5 | ≤0.5–>4 | 98.3/0.0/1.7 |
| Daptomycin | 0.25 | 0.5 | 0.06–2 | 99.9/—/— |
| Vancomycin | 1 | 1 | 0.25–2 | 100.0/0.0/0.0 |
| Oxacillin susceptible (1,537) | ||||
| Linezolid | 1 | 2 | 0.25–>8 | 99.9/0.0/0.1 |
| Ciprofloxacin | 0.25 | >4 | ≤0.03–>4 | 87.2/1.9/10.9 |
| Clindamycin | ≤0.25 | ≤0.25 | ≤0.25–>2 | 94.3/0.2/5.5 (13.8)b |
| Erythromycin | 0.25 | >16 | ≤0.12–>16 | 63.3/4.4/32.7 |
| Gentamicin | ≤1 | ≤1 | ≤1–>8 | 99.0/0.3/0.7 |
| Trimethoprim-sulfamethoxazole | ≤0.5 | ≤0.5 | ≤0.5–>4 | 99.5/0.0/0.5 |
| Daptomycin | 0.25 | 0.5 | ≤0.06–2 | 99.9/—/— |
| Vancomycin | 1 | 1 | 0.25–2 | 100.0/0.0/0.0 |
| CoNSc (753) | ||||
| Linezolid | 0.5 | 1 | ≤0.12–>8 | 99.1/0.0/0.9 |
| Oxacillin | 1 | >2 | ≤0.25–>2 | 36.5/0.0/63.5 |
| Ciprofloxacin | 0.25 | >4 | ≤0.03–>4 | 62.2/0.5/37.3 |
| Clindamycin | ≤0.25 | >2 | ≤0.25–>2 | 73.4/2.8/23.8 (9.6)b |
| Erythromycin | >16 | >16 | ≤0.12–>16 | 39.6/2.1/58.3 |
| Gentamicin | ≤1 | >8 | ≤1–>8 | 85.0/2.5/12.5 |
| Trimethoprim-sulfamethoxazole | ≤0.5 | >4 | ≤0.5—>4 | 72.6/0.0/27.4 |
| Daptomycin | 0.25 | 0.5 | ≤0.06–2 | 99.9/—/— |
| Vancomycin | 1 | 2 | ≤0.12–4 | 100.0/0.0/0.0 |
| Enterococcid (937) | ||||
| Linezolid | 1 | 2 | 0.25–>8 | 99.5/0.1/0.4 |
| Ampicillin | 1 | >8 | 0.5–>8 | 74.3/0.0/25.7 |
| Ciprofloxacin | 2 | >4 | 0.25–>4 | 49.1/6.8/44.1 |
| Piperacillin-tazobactam | 4 | >64 | 1–>64 | 74.3/—/— |
| Daptomycin | 1 | 2 | ≤0.06–4 | 100.0/—/— |
| Teicoplanin | ≤2 | >16 | ≤2–>16 | 77.7/1.0/21.3 |
| Vancomycin | 1 | >16 | 0.25–>16 | 76.6/0.5/22.9 |
| S. pneumoniae (1,273) | ||||
| Linezolid | 1 | 1 | ≤0.12–2 | 100.0/—/— |
| Amoxicillin-clavulanic acid | ≤1 | 4 | ≤1–>8 | 86.4/3.7/9.9 |
| Ceftriaxone | ≤0.06 | 1 | ≤0.06–8 | 91.5/7.3/1.2 |
| Ciprofloxacin | 1 | 2 | 0.12–>4 | —/—/— |
| Clindamycin | ≤0.25 | >2 | ≤0.25–>2 | 82.2/0.7/17.1 (1.3)b |
| Erythromycin | ≤0.12 | >16 | ≤0.12–>16 | 57.4/0.7/41.9 |
| Levofloxacin | 1 | 1 | 0.25–>4 | 99.2/0.1/0.7 |
| Penicilline | ≤0.06 | 4 | ≤0.06–8 | 57.7/24.1/18.2 |
| Vancomycin | 0.25 | 0.5 | ≤0.12–0.5 | 100.0/—/— |
| Viridans group streptococcif (526) | ||||
| Linezolid | 1 | 1 | ≤0.12–2 | 100.0/—/— |
| Ceftriaxone | 0.25 | 0.5 | ≤0.06–8 | 95.8/2.5/1.7 |
| Ciprofloxacin | 1 | 4 | ≤0.03–>4 | —/—/— |
| Clindamycin | ≤0.25 | >2 | ≤0.25–>2 | 87.6/0.6/11.8 |
| Erythromycin | 0.5 | 16 | ≤0.12–>16 | 48.5/2.8/48.7 |
| Levofloxacin | 1 | 2 | ≤0.12–>4 | 93.1/1.2/5.7 |
| Penicillin | ≤0.06 | 0.5 | ≤0.06–>8 | 73.6/24.1/2.3 |
| Vancomycin | 0.5 | 1 | ≤0.12–1 | 100.0/—/— |
| Beta-hemolytic streptococcig (960) | ||||
| Linezolid | 1 | 1 | ≤0.12–1 | 100.0/—/— |
| Ceftriaxone | ≤0.06 | 0.12 | ≤0.06–0.5 | 100.0/—/— |
| Ciprofloxacin | 0.5 | 1 | 0.12–>4 | —/—/— |
| Clindamycin | ≤0.25 | >2 | ≤0.25–>2 | 80.0/0.6/19.4 (5.5)b |
| Erythromycin | ≤0.12 | >16 | ≤0.12–>16 | 60.7/1.3/38.0 |
| Levofloxacin | ≤0.5 | 1 | ≤0.12–>4 | 98.9/0.2/0.9 |
| Penicillin | ≤0.06 | ≤0.06 | ≤0.06–0.12 | 100.0/—/— |
| Vancomycin | 0.5 | 0.5 | ≤0.12–1 | 100.0/—/— |
Criteria as published by the CLSI (11). %S, percent susceptible; %I, percent intermediate; %R, percent resistant; —, breakpoint not available.
Inducible clindamycin resistance rate among erythromycin-resistant, clindamycin-susceptible isolates as determined by the CLSI broth microdilution inducible clindamycin resistance screening test (11).
Includes [organism (no. of isolates)] S. auricularis (1), S. capitis (35), S. caprae (9), S. cohnii (5), S. epidermidis (462), S. haemolyticus (30), S. hominis (53), S. intermedius (5), S. lugdunensis (78), S. pasteuri (2), S. pettenkoferi (9), S. saprophyticus (35), S. schleiferi (2), S. simulans (13), S. warneri (12), and coagulase-negative staphylococci whose species was not determined (2).
Includes [organism (no. of isolates)] E. avium (9), E. casseliflavus (6), E. faecalis (640), E. faecium (259), E. gallinarum (7), E. gilvus (1), E. hirae (4), and E. raffinosus (11).
Criteria used were as published by the CLSI for “Penicillin oral penicillin V” (susceptible, ≤0.06 μg/ml; intermediate, 0.12 to 1 μg/ml; and resistant, ≥2 μg/ml) (11).
Includes 27 species.
Includes [organism (no. of isolates)] S. dysgalactiae (20), S. equisimilis (1), group A Streptococcus (S. pyogenes; 332), group B Streptococcus (S. agalactiae; 451), group C Streptococcus species (51), group F Streptococcus (9), and group G Streptococcus species (96).