TABLE 3.
Comparative activity of linezolid tested against 6,741 Gram-positive pathogens isolated during the 2015 LEADER Program
| Organism/resistance group (no. tested) and antimicrobial agent | MIC50 (μg/ml) | MIC90 (μg/ml) | Range (μg/ml) | CLSI (%S/%R)a |
|---|---|---|---|---|
| S. aureus | ||||
| Oxacillin susceptible (1,640) | ||||
| Linezolid | 1 | 1 | ≤0.12 to 2 | 100.0/0.0 |
| Vancomycin | 0.5 | 1 | ≤0.12 to 2 | 100.0/0.0 |
| Teicoplanin | ≤0.5 | ≤0.5 | ≤0.5 to 8 | 100.0/0.0 |
| Daptomycin | 0.25 | 0.5 | ≤0.12 to 1 | 100.0/— |
| Erythromycin | 0.25 | >8 | ≤0.06 to >8 | 64.6/28.1 |
| Clindamycin | ≤0.25 | ≤0.25 | ≤0.25 to >2 | 94.4/5.4 |
| Tetracycline | ≤0.5 | ≤0.5 | ≤0.5 to >8 | 95.9/3.2 |
| Tigecyclineb | 0.06 | 0.12 | ≤0.015 to 0.5 | 100.0/— |
| Gentamicin | ≤1 | ≤1 | ≤1 to >8 | 98.6/1.3 |
| Levofloxacin | 0.12 | 4 | ≤0.03 to >4 | 88.5/11.2 |
| Trimethoprim-sulfamethoxazole | ≤0.5 | ≤0.5 | ≤0.5 to >4 | 99.4/0.6 |
| Oxacillin resistant (1,391) | ||||
| Linezolid | 1 | 1 | ≤0.12 to >8 | 99.9/0.1 |
| Vancomycin | 0.5 | 1 | ≤0.12 to 2 | 100.0/0.0 |
| Teicoplanin | ≤0.5 | ≤0.5 | ≤0.5 to 8 | 100.0/0.0 |
| Daptomycin | 0.25 | 0.5 | ≤0.12 to 1 | 100.0/— |
| Erythromycin | >8 | >8 | ≤0.06 to >8 | 12.5/84.0 |
| Clindamycin | ≤0.25 | >2 | ≤0.25 to >2 | 72.6/26.9 |
| Tetracycline | ≤0.5 | ≤0.5 | ≤0.5 to >8 | 94.2/4.8 |
| Tigecyclineb | 0.06 | 0.12 | ≤0.015 to 0.5 | 100.0/— |
| Gentamicin | ≤1 | ≤1 | ≤1 to >8 | 96.1/3.8 |
| Levofloxacin | 4 | >4 | 0.12 to >4 | 30.7/67.6 |
| Trimethoprim-sulfamethoxazole | ≤0.5 | ≤0.5 | ≤0.5 to >4 | 97.2/2.8 |
| Coagulase-negative staphylococci | ||||
| Oxacillin susceptible (381)c | ||||
| Linezolid | 0.5 | 1 | ≤0.12 to 2 | 100.0/0.0 |
| Vancomycin | 0.5 | 2 | ≤0.12 to 2 | 100.0/0.0 |
| Teicoplanin | ≤0.5 | 4 | ≤0.5 to 8 | 100.0/0.0 |
| Daptomycin | 0.25 | 0.5 | ≤0.12 to 1 | 100.0/— |
| Erythromycin | 0.12 | >8 | ≤0.06 to >8 | 65.6/32.3 |
| Clindamycin | ≤0.25 | ≤0.25 | ≤0.25 to >2 | 91.1/7.9 |
| Tetracycline | ≤0.5 | 1 | ≤0.5 to >8 | 92.4/6.0 |
| Tigecyclineb | 0.06 | 0.12 | ≤0.015 to 0.5 | 100.0/0.0 |
| Gentamicin | ≤1 | ≤1 | ≤1 to >8 | 97.4/2.4 |
| Levofloxacin | 0.25 | 4 | ≤0.03 to >4 | 84.8/14.2 |
| Trimethoprim-sulfamethoxazole | ≤0.5 | 2 | ≤0.5 to >4 | 90.3/9.7 |
| Oxacillin resistant (543)d | ||||
| Linezolid | 0.5 | 1 | ≤0.12 to >8 | 98.7/1.3 |
| Vancomycin | 1 | 2 | ≤0.12 to 2 | 100.0/0.0 |
| Teicoplanin | 2 | 4 | ≤0.5 to 16 | 99.3/0.0 |
| Daptomycin | 0.5 | 0.5 | ≤0.12 to 1 | 100.0/— |
| Erythromycin | >8 | >8 | ≤0.06 to >8 | 22.8/74.2 |
| Clindamycin | ≤0.25 | >2 | ≤0.25 to >2 | 57.8/39.0 |
| Tetracycline | ≤0.5 | >8 | ≤0.5 to >8 | 82.7/16.0 |
| Tigecyclineb | 0.06 | 0.25 | 0.03 to 0.5 | 100.0/0.0 |
| Gentamicin | ≤1 | >8 | ≤1 to >8 | 65.9/30.8 |
| Levofloxacin | >4 | >4 | ≤0.03 to >4 | 39.8/57.6 |
| Trimethoprim-sulfamethoxazole | 1 | >4 | ≤0.5 to >4 | 63.5/36.5 |
| Enterococcus spp.e (973) | ||||
| Linezolid | 1 | 1 | ≤0.25 to 8 | 99.7/0.2 |
| Ampicillin | 1 | >8 | ≤0.5 to >8 | 76.6/23.4 |
| Vancomycin | 1 | >16 | ≤0.5 to >16 | 78.3/21.6 |
| Teicoplanin | ≤2 | >16 | ≤2 to >16 | 79.1/18.4 |
| Daptomycin | 1 | 2 | ≤0.25 to >8 | 99.8/— |
| Tigecyclineb | 0.06 | 0.12 | ≤0.015 to 0.5 | 99.8/0.0 |
| Levofloxacin | 1 | >4 | ≤0.5 to >4 | 59.3/39.0 |
| Piperacillin-tazobactam | 4 | >16 | ≤2 to >16 | 76.3/23.4 |
| S. pneumoniae (850) | ||||
| Linezolid | 1 | 1 | 0.25 to 2 | 100.0/— |
| Penicillinf | ≤0.06 | 1 | ≤0.06 to 4 | 96.7/0.0 |
| Penicilling | ≤0.06 | 1 | ≤0.06 to 4 | 63.2/7.5 |
| Amoxicillin-clavulanate | ≤0.03 | 2 | ≤0.03 to 4 | 95.2/1.9 |
| Ceftriaxoneh | 0.03 | 1 | ≤0.015 to >2 | 98.4/0.5 |
| Vancomycin | 0.25 | 0.25 | ≤0.03 to 0.5 | 100.0/— |
| Erythromycin | 0.03 | >2 | ≤0.015 to >2 | 56.5/42.9 |
| Clindamycin | ≤0.12 | >1 | ≤0.12 to >1 | 85.0/14.4 |
| Levofloxacin | 1 | 1 | 0.25 to >4 | 99.3/0.7 |
| Tetracycline | 0.25 | >4 | ≤0.12 to >4 | 80.1/19.7 |
| Tigecyclineb | 0.03 | 0.06 | 0.015 to 0.12 | 99.9/— |
| Trimethoprim-sulfamethoxazole | ≤0.5 | >4 | ≤0.5 to >4 | 74.7/14.0 |
| Viridans group and other streptococci (236)i | ||||
| Linezolid | 0.5 | 1 | ≤0.06 to 1 | 100.0/— |
| Penicillin | ≤0.03 | 0.5 | ≤0.03 to >4 | 79.1/2.7 |
| Ceftriaxone | 0.12 | 0.5 | ≤0.03 to >4 | 97.3/1.8 |
| Vancomycin | 0.5 | 0.5 | ≤0.06 to 1 | 100.0/— |
| Daptomycin | 0.5 | 0.5 | ≤0.06 to 1 | 100.0/— |
| Erythromycin | 0.5 | >4 | ≤0.03 to >4 | 46.7/48.4 |
| Clindamycin | 0.03 | >2 | ≤0.015 to >2 | 83.1/16.4 |
| Levofloxacin | 1 | 2 | ≤0.03 to >4 | 92.4/7.1 |
| Tetracycline | 1 | >8 | ≤0.25 to >8 | 56.4/39.6 |
| Tigecyclineb | 0.03 | 0.06 | ≤0.008 to 0.25 | 100.0/— |
| Beta-hemolytic streptococci (727)j | ||||
| Linezolid | 1 | 1 | 0.5 to 1 | 100.0/— |
| Penicillin | ≤0.03 | 0.06 | ≤0.03 to 0.12 | 100.0/— |
| Ceftriaxone | ≤0.03 | 0.06 | ≤0.03 to 0.25 | 100.0/— |
| Vancomycin | 0.25 | 0.5 | ≤0.06 to 1 | 100.0/— |
| Daptomycin | 0.12 | 0.5 | ≤0.06 to 1 | 100.0/— |
| Erythromycin | 0.06 | >4 | ≤0.03 to >4 | 60.8/38.2 |
| Clindamycin | 0.06 | >2 | ≤0.015 to >2 | 78.7/20.9 |
| Levofloxacin | 0.5 | 1 | 0.06 to >4 | 99.3/0.3 |
| Tetracycline | 4 | >8 | ≤0.25 to >8 | 49.7/48.8 |
| Tigecyclineb | 0.06 | 0.06 | 0.015 to 0.25 | 100.0/— |
Criteria employed were as published by the CLSI (18). %S/%R, percent susceptible/percent resistant; —, lack of resistant breakpoint.
U.S. FDA breakpoints were applied for tigecycline.
The organisms tested included Staphylococcus auricularis (2 isolates), S. capitis (36 isolates), S. caprae (10 isolates), S. condimenti (2 isolates), S. epidermidis (153 isolates), S. hemolyticus (12 isolates), S. hominis (32 isolates), S. lugdunensis (109 isolates), S. pseudintermedius (2 isolates), S. saprophyticus (2 isolates), S. schleiferi (2 isolates), S. simulans (11 isolates), and S. warneri (8 isolates).
The organisms tested included S. auricularis (1 isolate), S. capitis (13 isolates), S. cohnii (5 isolates), S. caprae (2 isolates), S. epidermidis (402 isolates), S. hemolyticus (37 isolates), S. hominis (35 isolates), S. lugdunensis (6 isolates), S. pettenkoferi (4 isolates), S. pseudintermedius/S. intermedius/S. delphini (1 isolate), S. saprophyticus (22 isolates), S. schleiferi (1 isolate), S. simulans (9 isolates), and S. warneri (5 isolates).
The organisms tested included Enterococcus avium (5 isolates), E. casseliflavus (6 isolates), E. durans (3 isolates), E. faecalis (676 isolates), E. faecium (270 isolates), E. gallinarum (11 isolates), E. raffinosus (1 isolate), and E. thailandicus (1 isolate).
Criteria employed were as published by the CLSI for penicillin parenteral (nonmeningitis) (18).
Criteria employed were as published by the CLSI for penicillin (oral penicillin V) (18).
Criteria employed were as published by the CLSI for nonmeningitis (18).
The organisms tested included Streptococcus anginosus (57 isolates), S. anginosus group (10 isolates), S. australis (2 isolates), S. constellatus (7 isolates), S. cristatus (2 isolates), S. equinus (1 isolate), S. gallolyticus (9 isolates), S. gordonii (2 isolates), S. infantarius (1 isolate), S. infantis (2 isolates), S. intermedius (9 isolates), S. lutetiensis (4 isolates), S. mitis (5 isolates), S. mitis group (8 isolates), S. mitis/S. oralis (47 isolates), S. mutans (3 isolates), S. oralis (33 isolates), S. parasanguinis (14 isolates), S. salivarius (6 isolates), S. salivarius group (4 isolates), S. sanguinis (8 isolates), and S. vestibularis (2 isolates).
The organisms tested included Streptococcus pyogenes (297 isolates), S. agalactiae (341 isolates), S. equi (1 isolate), and S. dysgalactiae (89 isolates).