TABLE 2.

Activities of besifloxacin and comparators against gram-negative bacteria

Species (no. of isolates and phenotypea) and test drug	MIC (μg/ml)
	Range	50%	90%	%Sb
Acinetobacter baumanii (n = 53)
Besifloxacin	0.015-64	16	32	NA
Moxifloxacin	0.03-128	8	32	NA
Ciprofloxacin	0.06->128	64	>128	35.8
Levofloxacin	0.03-128	8	64	37.7
Imipenem	0.12->8	2	>8	54.7
Tobramycin	0.12->64	4	>64	60.4
Ceftazidime	2->16	>16	>16	39.6
Acinetobacter calcoaceticus (n = 27)
Besifloxacin	0.06-32	0.5	16	NA
Moxifloxacin	0.015-128	2	8	NA
Ciprofloxacin	0.03->128	1	128	51.9
Levofloxacin	0.015-128	0.5	8	66.7
Imipenem	0.06->8	0.25	1	92.6
Tobramycin	0.12->64	1	>64	77.8
Ceftazidime	2->16	4	>16	63.0
Acinetobacter lwoffii (n = 50)
Besifloxacin	0.015-64	0.25	16	NA
Moxifloxacin	0.008-128	0.06	4	NA
Ciprofloxacin	0.004->128	0.12	16	84.0
Levofloxacin	0.015-64	0.12	4	86.0
Imipenem	≤0.03->8	0.06	0.5	94.0
Tobramycin	≤0.06->64	0.25	8	86.0
Ceftazidime	0.5->16	2	>16	76.0
Citrobacter freundii (n = 100)
Besifloxacin	0.015-32	0.25	4	NA
Moxifloxacin	0.03-32	0.12	4	85.0
Ciprofloxacin	0.004-64	0.03	2	87.0
Levofloxacin	0.015-32	0.06	2	90.0
Imipenem	≤0.03->8	0.25	0.5	99.0
Tobramycin	0.12->64	0.5	8	87.0
Ceftazidime	0.06->16	0.25	>16	78.0
Citrobacter koseri (n = 100)
Besifloxacin	0.03->8	0.06	0.25	NA
Moxifloxacin	0.015->8	0.03	0.25	NA
Gatifloxacin	0.008->8	0.015	0.12	99.0
Ciprofloxacin	0.004->8	0.008	0.06	99.0
Levofloxacin	0.015->8	0.03	0.12	99.0
Azithromycin	2->8	8	>8	NA
Tobramycin	0.25-16	0.5	1	99.0
Ceftazidime	0.06-4	0.12	0.5	100.0
Enterobacter aerogenes (n = 50)
Besifloxacin	0.03-16	0.25	8	NA
Moxifloxacin	0.03-64	0.12	16	80.0
Ciprofloxacin	0.008-64	0.015	16	80.0
Levofloxacin	0.03-64	0.06	16	80.0
Imipenem	0.12-4	0.5	1	100.0
Tobramycin	0.25-32	0.5	8	88.0
Ceftazidime	0.12->16	2	>16	62.0
Enterobacter cloacae (n = 50)
Besifloxacin	0.06-16	0.12	2	NA
Moxifloxacin	0.015-16	0.06	2	94.0
Ciprofloxacin	0.004-64	0.015	0.5	92.0
Levofloxacin	0.008-32	0.03	0.25	92.0
Imipenem	0.12-2	0.25	1	100.0
Tobramycin	0.25-32	0.5	8	88.0
Ceftazidime	0.12->16	0.5	>16	70.0
Haemophilus influenzae (n = 15; CIP-S)
Besifloxacin	0.008-0.25	0.015	0.03	NA
Moxifloxacin	0.015-0.5	0.015	0.06	100.0
Ciprofloxacin	0.008-1	0.008	0.015	100.0
Levofloxacin	0.008-1	0.015	0.015	100.0
Azithromycin	0.12-2	2	2	100.0
Tobramycin	1-16	2	8	NA
Penicillin	0.25->4	0.5	>4	NA
Haemophilus influenzae (n = 11; CIP-NS)
Besifloxacin	0.015-2	2	2	NA
Moxifloxacin	1-16	8	16	9.1
Ciprofloxacin	2-64	16	64	0
Levofloxacin	1-32	8	16	27.3
Azithromycin	0.5-8	1	8	81.8
Tobramycin	1-16	4	8	NA
Penicillin	0.5->4	1	2	NA
Klebsiella oxytoca (n = 50)
Besifloxacin	0.06-8	0.12	1	NA
Moxifloxacin	0.03-8	0.06	2	NA
Gatifloxacin	0.015-8	0.03	0.5	92.0
Ciprofloxacin	0.008->8	0.015	0.5	90.0
Levofloxacin	0.015-8	0.03	0.5	90.0
Azithromycin	8->8	>8	>8	NA
Tobramycin	0.25-8	0.5	1	96.0
Ceftazidime	0.03-1	0.12	0.5	100.0
Klebsiella pneumoniae (n = 100)
Besifloxacin	≤0.004-64	0.25	4	NA
Moxifloxacin	0.03-128	0.12	2	90.0
Ciprofloxacin	0.008->128	0.03	2	89.0
Levofloxacin	≤0.004-128	0.06	2	91.0
Imipenem	≤0.03-2	0.25	0.5	100.0
Tobramycin	0.12->64	0.25	1	93.0
Ceftazidime	≤0.03->16	0.12	1	92.0
Legionella pneumophila (n = 50)
Besifloxacin	0.015-0.06	0.03	0.03	NA
Moxifloxacin	0.015-0.06	0.03	0.06	NA
Gatifloxacin	0.015-0.06	0.03	0.06	NA
Ciprofloxacin	0.015-0.06	0.03	0.03	NA
Levofloxacin	0.015-0.06	0.03	0.03	NA
Azithromycin	0.03-1	0.12	1	NA
Tobramycin	0.25-4	1	2	NA
Moraxella catarrhalis (n = 101)
Besifloxacin	0.015-0.12	0.03	0.03	NA
Moxifloxacin	0.015-0.12	0.03	0.03	NA
Gatifloxacin	0.008-0.25	0.015	0.015	NA
Ciprofloxacin	0.008-0.25	0.015	0.015	100.0
Levofloxacin	0.015-0.5	0.015	0.03	100.0
Azithromycin	0.015-0.06	0.03	0.03	100.0
Tobramycin	0.03-0.5	0.25	0.25	NA
Oxacillin	0.25->8	4	8	NA
Morganella morganii (n = 51)
Besifloxacin	0.03->8	0.12	4	NA
Moxifloxacin	0.03->8	0.25	>8	NA
Gatifloxacin	0.015->8	0.12	>8	74.5
Ciprofloxacin	0.004->8	0.015	>8	76.5
Levofloxacin	0.015->8	0.06	8	76.5
Azithromycin	8->8	>8	>8	NA
Tobramycin	0.25-32	1	4	90.2
Ceftazidime	0.03->32	0.12	16	82.4
Neisseria meningitidis (n = 20)
Besifloxacin	≤0.004-0.03	0.008	0.015	NA
Moxifloxacin	≤0.004-0.015	0.008	0.008	NA
Ciprofloxacin	≤0.002-0.015	0.004	0.004	100.0
Levofloxacin	≤0.004-0.03	0.008	0.015	100.0
Azithromycin	≤0.03-0.12	0.06	0.06	100.0
Penicillin	≤0.06-0.25	≤0.06	0.12	50.0
Proteus mirabilis (n = 50)
Besifloxacin	0.06-32	0.25	16	NA
Moxifloxacin	0.06-128	0.25	16	62.0
Ciprofloxacin	0.015->128	0.03	32	64.0
Levofloxacin	0.015-32	0.03	8	76.0
Imipenem	0.06-4	1	2	100.0
Tobramycin	0.25-32	1	4	92.0
Ceftazidime	≤0.03-16	≤0.03	0.06	98.0
Proteus vulgaris (n = 50)
Besifloxacin	0.06-1	0.12	0.25	NA
Moxifloxacin	0.06-2	0.25	0.5	100.0
Ciprofloxacin	0.008-0.12	0.015	0.03	100.0
Levofloxacin	0.015-0.25	0.03	0.06	100.0
Imipenem	0.25-4	1	4	100.0
Tobramycin	0.25-64	1	2	98.0
Ceftazidime	≤0.03-2	0.06	0.12	100.0
Pseudomonas aeruginosa (n = 105; CIP-S)
Besifloxacin	0.5-8	1	4	NA
Moxifloxacin	0.5-16	2	4	NA
Ciprofloxacin	0.03-1	0.12	0.5	100.0
Levofloxacin	0.06-4	0.5	1	96.2
Imipenem	0.5->8	2	2	95.2
Tobramycin	0.25->64	0.5	1	97.1
Ceftazidime	0.5->16	2	8	93.3
Pseudomonas aeruginosa (n = 96; CIP-NS)
Besifloxacin	2-128	16	64	NA
Moxifloxacin	2->128	64	>128	NA
Ciprofloxacin	2->128	16	64	0
Levofloxacin	2->128	16	64	1.0
Imipenem	0.25->8	8	>8	44.8
Tobramycin	0.25->64	1	>64	64.6
Ceftazidime	0.25->16	4	>16	57.3
Serratia marcescens (n = 100)
Besifloxacin	0.12-2	0.25	1	NA
Moxifloxacin	0.06-4	0.25	1	98.0
Ciprofloxacin	0.015-2	0.06	0.5	98.0
Levofloxacin	0.03-1	0.12	0.5	100.0
Imipenem	0.12-2	0.5	1	100.0
Tobramycin	0.25->64	2	4	91.0
Ceftazidime	≤0.03->16	0.06	0.5	93.0
Stenotrophomonas maltophilia (n = 48; LVX-S)
Besifloxacin	0.25-8	1	4	NA
Moxifloxacin	0.03-1	0.5	1	NA
Ciprofloxacin	0.5-8	2	4	33.3
Levofloxacin	0.12-2	1	2	100.0
Imipenem	>8	>8	>8	0
Tobramycin	1->64	16	>64	22.9
Ceftazidime	0.5->16	16	>16	43.8
Stenotrophomonas maltophilia (LVX-NS; n = 52)
Besifloxacin	1->128	16	64	NA
Moxifloxacin	0.5-64	8	32	NA
Ciprofloxacin	4-128	32	64	0
Levofloxacin	4-64	8	32	0
Imipenem	2->8	>8	>8	1.9
Tobramycin	0.25->64	16	>64	38.5
Ceftazidime	0.5->16	>16	>16	32.7

^aCIP-S, ciprofloxacin susceptible; CIP-NS, non-ciprofloxacin susceptible; LVX-S, levofloxacin susceptible; LVX-NS, non-levofloxacin susceptible.

^bPercentage of susceptible isolates (9); breakpoints have not been defined for all agent-species combinations. NA, not applicable.