Table 2.

Comparative activity of linezolid tested against 6,414 Gram-positive pathogens isolated during the 2009 LEADER Program

Organism, resistance group (no. tested), and antimicrobial agentMIC (μg/ml)% of isolates susceptible/% resistanta
50%90%Range
S. aureus
    Oxacillin susceptible (1,584)
        Linezolid22≤0.06–2100.0/0.0
        Oxacillin0.51≤0.25–2100.0/0.0
        Ceftriaxone44≤0.25–3299.4/0.0
        Ciprofloxacin≤0.52≤0.5–>488.3/9.9
        Clindamycin≤0.25≤0.25≤0.25–>295.1/4.5
        Daptomycin0.250.5≤0.06–1100.0/−
        Erythromycin0.5>2≤0.25–>267.2/32.1
        Gentamicin≤2≤2≤2–>899.2/0.5
        Levofloxacin≤0.52≤0.5–>489.7/9.7
        Penicillin216≤0.015–>3222.9/77.1
        Quinupristin-dalfopristin0.50.5≤0.25–299.9/0.0
        Teicoplanin≤2≤2≤2–4100.0/0.0
        Tetracycline≤2≤2≤2–>896.8/2.3
        Trimethoprim-sulfamethoxazole≤0.5≤0.5≤0.5–>299.0/1.0
        Vancomycin11≤0.12–2100.0/0.0
    Oxacillin resistant (1,673)
        Linezolid220.25–>899.7/0.3
        Ciprofloxacin>4>4≤0.5–>425.3/73.2
        Clindamycin≤0.25>2≤0.25–>266.5/33.0
        Daptomycin0.50.5≤0.06–1100.0/−
        Erythromycin>2>2≤0.25–>28.3/91.5
        Gentamicin≤2≤2≤2–>897.6/2.3
        Levofloxacin>4>4≤0.5–>426.9/72.2
        Quinupristin-dalfopristin0.51≤0.25–299.6/0.0
        Teicoplanin≤2≤2≤2–8100.0/0.0
        Tetracycline≤2≤2≤2–>895.0/4.7
        Trimethoprim-sulfamethoxazole≤0.5≤0.5≤0.5–>298.1/1.9
        Vancomycin110.25–2100.0/0.0
CoNS
    Oxacillin susceptible (213)b
        Linezolid11≤0.06–899.5/0.5
        Ceftriaxone24≤0.25–1698.1/0.0
        Ciprofloxacin≤0.5>4≤0.5–>480.3/19.7
        Clindamycin≤0.252≤0.25–>288.7/9.9
        Daptomycin0.250.5≤0.06–1100.0/−
        Erythromycin≤0.25>2≤0.25–>256.6/42.5
        Gentamicin≤2≤2≤2–>898.1/0.9
        Levofloxacin≤0.5>4≤0.5–>479.8/19.7
        Quinupristin-dalfopristin≤0.25≤0.25≤0.25–1100.0/0.0
        Teicoplanin≤24≤2–8100.0/0.0
        Tetracycline≤28≤2–>889.2/9.4
        Trimethoprim-sulfamethoxazole≤0.5>2≤0.5–>287.3/12.7
        Vancomycin12≤0.12–2100.0/0.0
    Oxacillin resistant (603)c
        Linezolid110.25–>898.2/1.8
        Ciprofloxacin>4>4≤0.5–>431.2/67.7
        Clindamycin≤0.25>2≤0.25–>259.7/38.8
        Daptomycin0.250.5≤0.06–1100.0/−
        Erythromycin>2>2≤0.25–>224.9/73.8
        Gentamicin≤2>8≤2–>864.7/27.4
        Levofloxacin>4>4≤0.5–>430.8/67.2
        Quinupristin-dalfopristin≤0.250.5≤0.25–299.8/0.0
        Teicoplanin≤28≤2–1696.2/0.0
        Tetracycline≤2>8≤2–>883.7/15.8
        Trimethoprim-sulfamethoxazole2>2≤0.5–>250.5/49.5
        Vancomycin22≤0.12–4100.0/0.0
Enterococcus spp. (1,017)d
    Linezolid120.25–>898.9/0.8
    Ampicillin2>16≤1–>1667.8/32.2
    Ciprofloxacin>4>4≤0.5–>437.9/53.9
    Daptomycin12≤0.06–899.9/−
    Erythromycin>2>2≤0.25–>29.0/70.1
    Levofloxacin>4>4≤0.5–>445.4/52.6
    Quinupristin-dalfopristin>2>2≤0.25–>231.7/63.9
    Teicoplanin≤2>16≤2–>1671.8/26.8
    Vancomycin2>160.25–>1670.3/29.0
S. pneumoniae (659)
    Linezolid11≤0.12–2100.0/−
    Amoxicillin-clavulanate≤18≤1–1681.8/15.5
    Ceftriaxone≤0.252≤0.25–887.1/2.1
    Clindamycin≤0.25>2≤0.25–>277.8/21.6
    Erythromycin≤0.25>2≤0.25–>258.1/41.1
    Levofloxacin11≤0.5–>499.1/0.9
    Penicilline≤0.034≤0.03–>483.6/2.4
    Penicillinf≤0.034≤0.03–>457.7/21.5
    Quinupristin-dalfopristin0.50.5≤0.25–299.5/0.0
    Tetracycline≤2>8≤2–>875.9/23.8
    Trimethoprim-sulfamethoxazole≤0.5>2≤0.5–>263.7/29.6
    Vancomycin≤11≤1–1100.0/−
Viridans group streptococci (264)g
    Linezolid110.12–2100.0/−
    Ceftriaxone≤0.251≤0.25–>3291.7/3.8
    Clindamycin≤0.250.5≤0.25–>288.6/9.1
    Daptomycin0.251≤0.06–299.6/−
    Erythromycin1>2≤0.25–>246.2/50.8
    Levofloxacin12≤0.5–>490.2/8.0
    Penicillin0.061≤0.015–3277.3/3.0
    Quinupristin-dalfopristin0.51≤0.25–>297.7/0.4
    Tetracycline≤2>8≤2–>860.6/36.4
    Vancomycin0.51≤0.12–299.6/−
Beta-hemolytic streptococci (401)h
    Linezolid11≤0.06–2100.0/−
    Ceftriaxone≤0.25≤0.25≤0.25–0.5100.0/−
    Clindamycin≤0.25>2≤0.25–>281.8/17.2
    Daptomycin0.120.25≤0.06–0.5100.0/−
    Erythromycin≤0.25>2≤0.25–>262.8/36.4
    Levofloxacin≤0.51≤0.5–>499.5/0.5
    Penicillin0.030.06≤0.015–0.12100.0/−
    Quinupristin-dalfopristin≤0.250.5≤0.25–1100.0/0.0
    Tetracycline>8>8≤2–>839.2/58.9
    Vancomycin0.50.5≤0.12–1100.0/−
  • a Criteria as published by the CLSI (2010); β-lactam susceptibility should be directed by the oxacillin test results. −, no interpretive criteria for this category.

  • b Includes Staphylococcus capitis (9 isolates), Staphylococcus epidermidis (47 isolates), Staphylococcus haemolyticus (1 isolate), Staphylococcus hominis (7 isolates), Staphylococcus intermedius (2 isolates), Staphylococcus lugdunensis (1 isolate), Staphylococcus saccharolyticus (1 isolate), Staphylococcus saprophyticus (2 isolates), Staphylococcus schleiferi (1 isolate), Staphylococcus warnerii (4 isolates), and coagulase-negative staphylococci not determined to the species level (138 isolates).

  • c Includes Staphylococcus auricularis (3 isolates), Staphylococcus capitis (3 isolates), Staphylococcus epidermidis (187 isolates), Staphylococcus haemolyticus (14 isolates), Staphylococcus hominis (22 isolates), Staphylococcus lugdunensis (14 isolates), Staphylococcus saprophyticus (8 isolates), Staphylococcus simulans (3 isolates), Staphylococcus warnerii (7 isolates), and coagulase-negative staphylococci not determined to the species level (342 isolates).

  • d Includes Enterococcus avium (9 isolates), Enterococcus casseliflavus (9 isolates), Enterococcus durans (5 isolates), Enterococcus faecalis (635 isolates), Enterococcus faecium (339 isolates), Enterococcus gallinarum (9 isolates), Enterococcus hirae (2 isolates), Enterococcus raffinosus (3 isolates), and enterococci not determined to the species level (6 isolates).

  • e CLSI (2010) criteria for “penicillin parenteral (nonmeningitis)” (susceptible at ≤2 μg/ml and resistant at ≥8 μg/ml).

  • f CLSI (2010) criteria for “penicillin parenteral (oral penicillin V)” (susceptible at ≤0.06 μg/ml and resistant at ≥2 μg/ml).

  • g Includes Streptococcus anginosus (15 isolates), Streptococcus bovis (9 isolates), Streptococcus constellatus (7 isolates), Streptococcus equinus (1 isolate), Streptococcus gallolyticus (2 isolates), Streptococcus gordonii (1 isolate), Streptococcus intermedius (4 isolates), Streptococcus milleri (2 isolates), Streptococcus mitis (42 isolates), Streptococcus oralis (7 isolates), Streptococcus parasanguinis (7 isolates), Streptococcus porcinus (1 isolate), Streptococcus salivarius (14 isolates), Streptococcus sanguinis (8 isolates), Streptococcus vestibularis (1 isolate), alpha-hemolytic streptococci not determined to the species level (3 isolates), and viridans group streptococci not determined to the species level (140 isolates).

  • h Includes Streptococcus dysgalactiae (8 isolates), group A streptococci (121 isolates), group B streptococci (217 isolates), group C streptococci (15 isolates), and group G streptococci (40 isolates).