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. 2005 Mar;43(3):1294–1300. doi: 10.1128/JCM.43.3.1294-1300.2005

TABLE 1.

MIC ranges, MIC50sa, MIC90s, and resistance rates of 82 erythromycin A-resistant pneumococcal isolates from seven European countries

Antibioticb MIC range MIC50 MIC90 Susceptible
Intermediate
Resistant
No. % No. % No. %
All strains (n = 82)
    Erythromycin A 1-≥32 ≥32 ≥32 0 0 0 0 82 100
    Roxithromycin 0.5-≥32 ≥32 ≥32 0 0 1 1.2 81 98.8
    Clarithromycin 1-≥32 ≥32 ≥32 0 0 0 0 82 100
    Azithromycin 1-≥32 ≥32 ≥32 0 0 5 6.1 77 93.9
    Spiramycin 0.03-≥32 ≥32 ≥32 ND ND ND ND ND ND
    Clindamycin 0.06-≥32 16 ≥32 17 20.7 1 1.2 64 78.0
    Telithromycin ≤0.03-0.5 ≤0.03 0.25 82 100 0 0 0 0
    Q-D 0.03-2 0.5 1 80 97.6 2 2.4 0 0
    Penicillin G 0.016-2 1 1 19 23.2 57 69.5 6 7.3
    Cefotaxime 0.016-2 1 1 78 95.1 4 4.9 0 0
    Amoxicillin 0.016-2 1 1 82 100 0 0 0 0
    Tetracycline 0.06-≥32 16 ≥32 8 9.8 12 14.6 62 75.6
    Ciprofloxacin 0.06-2 1 1 ND ND ND ND ND ND
    Vancomycin 0.125-0.5 0.25 0.25 82 100 0 0 0 0
    Teicoplanin 0.06-0.25 0.06 0.125 ND ND ND ND ND ND
Erm(B)-positive strains (n = 64)
    Erythromycin A 4-≥32 ≥32 ≥32 0 0 0 0 64 100
    Roxithromycin 4-≥32 ≥32 ≥32 0 0 0 0 64 100
    Clarithromycin 2-≥32 ≥32 ≥32 0 0 0 0 64 100
    Azithromycin 1-≥32 ≥32 ≥32 0 0 1 1.6 63 98.4
    Spiramycin 2-≥32 ≥32 ≥32 ND ND ND ND ND ND
    Clindamycin 2-≥32 ≥32 ≥32 0 0 0 0 64 100
    Telithromycin ≤0.03-0.5 ≤0.03 0.25 64 100 0 0 0 0
    Q-D 0.03-2 0.5 1 62 96.9 2 3.1 0 0
    Penicillin G 0.016-2 1 1 16 25.0 44 68.8 4 6.3
    Cefotaxime 0.016-2 0.5 1 62 96.9 2 3.1 0 0
    Amoxicillin 0.016-2 1 2 64 100 0 0 0 0
    Tetracycline 0.125-≥32 16 ≥32 0 0 3 4.7 61 95.3
    Ciprofloxacin 0.06-2 1 1 ND ND ND ND ND ND
    Vancomycin 0.125-0.5 0.25 0.25 64 100 0 0 0 0
    Teicoplanin 0.06-0.25 0.06 0.125 ND ND ND ND ND ND
mef(A)-positive strains (n = 18)
    Erythromycin A 1-8 2 8 0 0 0 0 18 100
    Roxithromycin 0.5-16 4 8 0 0 1 5.6 17 94.4
    Clarithromycin 1-16 2 8 0 0 0 0 18 100
    Azithromycin 1-16 2 16 0 0 4 22.2 14 77.8
    Spiramycin 0.03-8 2 4 ND ND ND ND ND ND
    Clindamycin 0.06-0.5 0.06 0.25 17 94.4 1 5.6 0 0
    Telithromycin ≤0.03-0.125 0.03 0.06 18 100 0 0 0 0
    Q-D 0.25-1 0.5 1 18 100 0 0 0 0
    Penicillin G 0.016-2 1 2 3 16.7 13 72.2 2 11.1
    Cefotaxime 0.016-2 1 1 16 88.9 2 11.1 0 0
    Amoxicillin 0.016-2 1 1 18 100 0 0 0 0
    Tetracycline 0.06-32 8 32 7 38.9 9 50.0 2 11.1
    Ciprofloxacin 0.25-2 0.5 2 ND ND ND ND ND ND
    Vancomycin 0.03-0.25 0.25 0.25 18 100 0 0 0 0
    Teicoplanin 0.03-0.125 0.06 0.125 ND ND ND ND ND ND
a

MIC50 and MIC90, MICs at which 50 and 90% of isolates, respectively, are inhibited.

b

Breakpoints (intermediate and resistant) are as follows according to NCCLS (19): erythromycin A, 0.5 μg/ml and ≥1 μg/ml; clarithromycin, 0.5 μg/ml and ≥1 μg/ml; azithromycin, 1 μg/ml and ≥2 μg/ml; clindamycin, 0.5 μg/ml and ≥1 μg/ml; telithromycin, 2 μg/ml and ≥4 μg/ml, quinupristin-dalfopristin (Q-D), 2 μg/ml and ≥4 μg/ml; penicillin G, 0.1 to 1 μg/ml and ≥2 μg/ml; cefotaxime (nonmeningitis), 2 μg/ml and ≥4 μg/ml; amoxicillin, 4 μg/ml and ≥8 μg/ml; tetracycline, 4 μg/ml and ≥8 μg/ml; vancomycin (susceptible), ≤1 μg/ml. Roxithromycin breakpoints are not NCCLS approved. The breakpoints ≤1 μg/ml and ≥2 μg/ml were used. Ciprofloxacin, spiramycin, and teicoplanin breakpoints are not available. ND, not determined.