TABLE 3.

Comparison of phenotypes and genotypes of erythromycin-resistant GBS isolates^a

Phenotypeb	Genotype	No. of isolates	MIC (μg/ml)
			Erythromycin		Clindamycin
			90%	Range	90%	Range
M	mefA	7	8	8-32	0.06	0.06-0.125
iMLSB	ermTR	22	16	≥1,024	0.25	0.06-0.25
cMLSB	ermB	19	≥1,024	4-≥1,024	1,024	4-≥1,024
cMLSB	ermTR	5	8	256-≥1,024	≥1,024	512-≥1,024
cMLSB	ermTR, ermB	1		≥1,024		≥1,024
cMLSB	ermTR, mefA	1		≥1,024		≥1,024
L	linB	1		0.06		8
Unknown		2		0.06-0.125		0.5-2

^aA total of 55 isolates were tested.

^bAbbreviations: M, efflux; iMLS_B, inducible MLS_B resistance; cMLS_B, constitutive MLS_B resistance; L, lincomycin nucleotidyltransferase.