TABLE 1.

Antibiotic susceptibility of F₄₂₀-deficient mycobacteria^a

Substrate	MIC (μg · ml−1)			MIC ratio (WT/mutant)b
	WT	fgd::kan	fbiC::kan
Quinone analogues
Menadione	32	2	2	16
1,4-Naphthoquinone	32	1	1	32
1,2-Naphthoquinone	32	2	2	16
Furanocoumarins and aminocoumarins
Methoxsalen	64	1	1	64
Angelicin	128	1	1	128
Imperatorin	32	0.5	0.5	64
Novobiocin	0.5	0.5	0.5	1
Arylmethane dyes
Malachite green	64	1	0.5	64, 128
Crystal violet	16	1	0.5	16, 32
Phenol red	8	0.5	0.5	16
Azure B	16	2	2	8
Quinolones and fluoroquinolones
Oxolinic acid	16	0.125	0.125	128
Nalidixic acid	128	1	1	128
Ciprofloxacin	0.25	3.1 × 10−2	7.8 × 10−3	8
Moxifloxacin	6.3 × 10−2	6.3 × 10−2	3.1 × 10−2	1, 2
Clinical antimycobacterials
Rifampin	4	2	2	2
Ethambutol	0.5	0.13	0.13	4
Isoniazid	32	16	16	2
Pyrazinamide	512	256	256	2
Clofazimine	8	4	4	2

^aMICs are shown for exponential-phase wild-type (WT), fgd mutant, and fbiC mutant cultures. MICs were determined by serially diluting antibiotic stocks in 96-well plates and measuring growth inhibition by the OD₆₀₀. Five first-line antimycobacterials (rifampin, ethambutol, isoniazid, pyrazinamide, and clofazimine) and 1 second-line antimycobacterial (moxifloxacin) were tested.

^bCells with two values are the ratios for the fgd::kan mutant and fbiC::kan mutant, respectively.