Table 4. MIC determination and susceptibility testing for the strains exposed to isoniazid in the presence and absence of efflux inhibitors.

	INH MIC (µg/ml) (Susceptibility testing for INH)
	#0			#1				#26
Strain	+TZ	+CPZ	+VP	no EI	+TZ	+CPZ	+VP	no EI	+TZ	+CPZ	+VP
H37Rv INH (a)	0.05 (S)	0.05 (S)	0.05 (S)	128 (R)	128 (R)	0.05 (S)	0.06 (S)	128 (R)	128 (R)	128 (R)	128 (R)
H37Rv INH (b)	0.05 (S)	0.05 (S)	0.05 (S)	128 (R)	128 (R)	0.1 (S)	0.1 (S)	128 (R)	128 (R)	0.1 (S)	0.1 (S)
401/06 INH (a)	0.1 (S)	0.1 (S)	0.1 (S)	256 (R)	256 (R)	128 (R)	256 (R)	256 (R)	256 (R)	128 (R)	256 (R)
401/06 INH (b)	0.1 (S)	0.1 (S)	0.1 (S)	64 (R)	0.1(S)	0.1 (S)	0.1 (S)	256 (R)	256 (R)	64 (R)	256 (R)
267/05 INH (a)	0.1 (S)	0.1 (S)	0.1 (S)	128 (R)	0.1 (S)	0.1 (S)	128 (R)	128 (R)	0.1 (S)	0.1 (S)	128 (R)
267/05 INH (b)	0.1 (S)	0.1 (S)	0.1 (S)	128 (R)	0.1 (S)	0.1 (S)	128 (R)	128 (R)	0.1 (S)	0.1 (S)	128 (R)
359/03 INH (a)	0.05 (S)	0.05 (S)	0.05 (S)	256 (R)	128 (R)	0.1 (S)	0.03 (S)	256 (R)	128 (R)	0.1 (S)	0.03 (S)
359/03 INH (b)	0.05 (S)	0.05 (S)	0.05 (S)	128 (R)	0.1 (S)	0.1 (S)	0.1 (S)	256 (R)	128 (R)	0.1 (S)	0.1 (S)

Legend: INH: isoniazid; INH (a): exposure process A; INH (b): exposure process B. S: susceptible; R: resistant. Values in bold correspond to full reversion of the INH resistance phenotype. EIs were used at ½ of their MIC. MICs for the EIs (passage 1): thioridazine (TZ): H37Rv and 359/03: 15 µg/ml, 401/06 and 267/05: 30 µg/ml; chlorpromazine (CPZ): 30 µg/ml for all strains; verapamil (VP): 256 µg/ml for all strains. MICs for the EIs (passage 26): TZ: H37Rv and 359/03: 15 µg/ml, 401/06(a)26: 15 µg/ml; 401/06(b)26: 30 µg/ml; 267/05: 30 µg/ml; CPZ: MIC of 30 µg/ml for all strains except H37Rv INH(a)26: 15 µg/ml; VP: 256 µg/ml for all strains except H37Rv INH(a)26 and 401/06: 128 µg/ml.