TABLE 1.

Comparison of the in vitro activities of five antimicrobial agents against 1,601 isolates of S. pneumoniae by penicillin category^a

Antimicrobial	Penicillin-susceptible strains (n = 1,127)					Penicillin-intermediate strains (n = 278)					Penicillin-resistant strains (n = 196)					All strains (n = 1,601)
	MIC50	MIC90	MIC range	% I	% R	MIC50	MIC90	MIC range	% I	% R	MIC50	MIC90	MIC range	% I	% R	MIC50	MIC90	MIC range	% I	% R
ABT-773	≤0.008	≤0.008	≤0.008–0.5			≤0.008	0.03	≤0.008–0.5			0.015	0.12	≤0.008–0.25			≤0.008	0.03	≤0.008–0.5
Clarithromycin	≤0.03	≤0.03	≤0.03–>64	0.5	5.2	≤0.03	>64	≤0.03–>64	2.2	35.3	2	>64	≤0.03–>64	3.6	64.8	≤0.03	4	≤0.03–>64	1.2	17.7
Erythromycin	0.06	0.06	≤0.03–>64	0.3	5.7	0.06	>64	≤0.03–>64	0.7	37.4	4	>64	≤0.03–>64	0.5	68.4	0.06	8	≤0.03–>64	0.4	18.9
Azithromycin	0.06	0.12	≤0.03–>64	0.2	5.6	0.12	>64	≤0.03–>64	0.7	37.8	8	>64	≤0.03–>64	1.5	67.3	0.12	16	≤0.03–>64	0.4	18.7
Clindamycin	0.06	0.06	≤0.008–>8	0.1	1.1	0.06	>8	≤0.008–8	0.0	12.9	0.06	>8	≤0.008–>8	0.5	21.4	0.06	0.06	≤0.008–>8	0.1	5.6

^aPenicillin susceptible, MIC ≤ 0.06 μg/ml; penicillin intermediate, MIC of 0.12 to 1 μg/ml; penicillin resistant, MIC ≥ 2 μg/ml. % I, percent intermediate; % R, percent resistant. MICs are expressed as micrograms per milliliter.