TABLE 1.

Activity of various quinolones against B. fragilis group fecal strains

Organism (no. of strains)	MIC range (μg/ml)	MIC50a (μg/ml)	No. of resistant strainsb
B. fragilis (8)
Ciprofloxacin	2.0–>256	256	7
Levofloxacin	1.0–128	2.0	4
Moxifloxacin	0.5–32	1.0	4
Clinafloxacin	0.125–32	0.25	4
B. ovatus (3)
Ciprofloxacin	8–256	16	3
Levofloxacin	4–256	8	3
Moxifloxacin	1.0–2.0	0	0
Clinafloxacin	0.25–2.0	0.5	0
B. thetaiotaomicron (5)
Ciprofloxacin	8–256	64	5
Levofloxacin	2.0–256	8.0	4
Moxifloxacin	0.5–32	4.0	3
Clinafloxacin	1.0–8.0	1.0	2
B. uniformis (6)
Ciprofloxacin	32–256	256	6
Levofloxacin	16–128	64	6
Moxifloxacin	2.0–64	32	5
Clinafloxacin	0.25–32	8.0	5
B. vulgatus (22)
Ciprofloxacin	8–>256	256	22
Levofloxacin	2.0–256	128	20
Moxifloxacin	1.0–128	32	20
Clinafloxacin	0.125–32	8.0	20
All (44)
Ciprofloxacin	2.0–>256	256	43
Levofloxacin	2.0–256	128	37
Moxifloxacin	0.25–128	16	32
Clinafloxacin	0.125–32	8.0	31

^aMIC₅₀, MIC for 50% of strains. 

^bMIC values of ≥4 μg/ml are considered as indicating resistance; see text.