TABLE 1.

MICs (micrograms per milliliter) for 585 pneumococcal strainsa

Drug and strain groupMIC rangeMIC50MIC90
Penicillin G
    All strains≤0.008->160.032
    Penicillin S≤0.008-0.060.030.03
    Penicillin I0.125-10.51
    Penicillin R2->1624
    Quinolone S≤0.008->160.032
    Quinolone N0.008-424
Amoxicillin-clavulanic acid
    All strains≤0.008-160.032
    Penicillin S≤0.008-0.1250.030.03
    Penicillin I0.03-20.251
    Penicillin R0.125-1622
    Quinolone S≤0.008-160.031
    Quinolone N0.016-412
Erythromycin
    All strains≤0.008->640.03>64
    Penicillin S≤0.008->640.030.06
    Penicillin I≤0.008->640.03>64
    Penicillin R≤0.008->640.03>64
    Quinolone S≤0.008->640.03>64
    Quinolone N≤0.008->640.03>64
Ciprofloxacin
    All strains0.5->3212
    Penicillin S0.5-812
    Penicillin I0.5-412
    Penicillin R0.5->3218
    Quinolone S0.5-212
    Quinolone N4->32816
Levofloxacin
    All strains0.5-3212
    Penicillin S0.5-812
    Penicillin I1-412
    Penicillin R0.5-32116
    Quinolone S0.5-212
    Quinolone N2-32416
Gemifloxacin
    All strains≤0.008-0.50.030.06
    Penicillin S≤0.008-0.1250.030.06
    Penicillin I0.016-0.060.030.06
    Penicillin R0.016-0.50.030.125
    Quinolone S0.008-0.060.030.06
    Quinolone N0.03-0.50.060.125
Gatifloxacin
    All strains0.125-80.250.5
    Penicillin S0.125-2.00.250.5
    Penicillin I0.25-1.00.250.5
    Penicillin R0.25-8.00.254
    Quinolone S0.125-0.50.250.5
    Quinolone N0.5-814
Moxifloxacin
    All strains0.06-40.1250.25
    Penicillin S0.06-0.50.1250.25
    Penicillin I0.06-0.250.1250.25
    Penicillin R0.125-40.1252
    Quinolone S0.06-0.50.1250.25
    Quinolone N0.25-40.52
  • a Of 585 strains tested, 378 were susceptible, 127 strains were intermediate, and 80 strains were resistant to penicillin and 564 strains were susceptible and 21 were nonsusceptible to quinolones. Quinolone nonsusceptibility is defined by a ciprofloxacin MIC of ≥4 μg/ml. S, susceptible; I, intermediate; R, resistant; N, nonsusceptible.