TABLE 1.

S. pneumoniae strains used and in vitro antibiotic activity

Strain	Genotype	MICa (μg/ml) of:
		ABT-773	Erythromycin
2486	Susceptible	≤0.002	0.03
5635	Susceptible	≤0.002	0.03
5649	mefb	0.06	8.0
5970c	ermB	0.008	>128
6395d	ermB	0.5	>128
1813d	ermB	1	>128

^aMIC determined by broth microdilution reference method (11). 

^bGene designation for macrolide efflux pump. 

^cStrain containing ermB methyltransferase gene with low residual ribosome methylation levels. 

^dStrain containing ermB methyltransferase gene with high residual ribosome methylation levels.