TABLE 5.

S. pneumoniae multistep selection results^a

Strain no.	Phenotype (resistance determinant)a	Drugb	Initial MIC (μg/ml)	Selected resistance		Retest MICc after passages in subinhibitory concns of the following antibiotic and 10 antibiotic-free subcultures:
				MIC (μg/ml)	No. of passages	CEM	AZI	CLA	TEL	CLI
1077	Macrolide S	CEM	0.008	0.06	43	0.06	0.03	0.06	0.06	0.03
		AZI	0.03	>64	29	0.03	>64	>64	0.125	4
		CLA	0.016	0.008	50
		TEL	0.004	0.25	15	0.06	>64	>64	0.25	8
		CLI	0.016	4	49	0.06	>64	>64	0.06	8
24	Macrolide R [erm(B)]	CEM	0.004	0.06	14	0.06	>64	>64	0.125	>64
		AZI	>64	NTd	NT
		CLA	>64	NT	NT
		TEL	0.25	32	14	0.06	>64	>64	16	>64
		CLI	>64	NT	NT
3665	Macrolide R [mef(A)]	CEM	0.03	0.5	14	0.5	16	4	0.25	0.03
		AZI	8	16	50
		CLA	2	16	26	0.06	8	8	0.06	0.03
		TEL	0.125	2	14	0.03	4	2	0.25	0.03
		CLI	0.016	0.03	50
1076	Macrolide-R [erm(B) mef(A)]	CEM	1	32	18	32	>64	>64	32	>64
		AZI	>64	NT	NT
		CLA	>64	NT	NT
		TEL	0.5	>64	14	2	>64	>64	>64	>64
		CLI	64	NT	NT
1635	Macrolide R [erm(A)]	CEM	0.008	0.06	32	0.125	4	1	0.03	0.03
		AZI	2	>64	14	0.004	>64	>64	0.004	0.03
		CLA	0.5	>64	49	0.008	>64	>64	0.016	0.25
		TEL	0.004	0.008	50
		CLI	0.06	>64	14	0.004	4	0.5	0.008	>64
2686	Macrolide R (L4 mutation)	CEM	0.03	0.5	22	1	>64	32	0.25	0.03
		AZI	>64	NT	NT
		CLA	8	>64	14	0.03	>64	>64	0.06	0.03
		TEL	0.06	0.5	25	0.016	>64	16	0.5	0.03
		CLI	0.03	0.125	50
7127	Macrolide S (S20N in L4, A105V in L22)	CEM	0.008	0.125	16	0.06	0.06	0.125	0.06	0.03
		AZI	0.06	0.5	29	0.016	1	0.5	0.016	0.06
		CLA	0.03	16	15	0.008	>64	16	0.008	1
		TEL	0.008	0.06	38	0.008	0.06	0.06	0.03	0.03
		CLI	0.03	0.25	43	0.004	0.03	0.016	0.008	0.25
3009	Macrolide R (23S rRNA mutation)	CEM	0.016	0.25	20	0.25	>64	>64	0.06	1
		AZI	>64	NT	NT
		CLA	16	>64	25	0.03	>64	64	0.06	1
		TEL	0.016	0.03	50
		CLI	1	2	50

^aS, susceptible; R, resistant.

^bCEM, CEM-101; AZI, azithromycin; CLA, clarithromycin; TEL, telithromycin; CLI, clindamycin.

^cBoldface indicates cross-reactivity.

^dNT, not tested.