Table 4.

Activities of BC-3781 and comparator antimicrobial agents against bacterial pathogens causing predominantly respiratory tract infections

Organism (no. tested) and antimicrobial agent	MIC50 (μg/ml)	MIC90 (μg/ml)	Range (μg/ml)	CLSI %S/%Ra	EUCAST %S/%Ra
S. pneumoniae (1,473)
BC-3781	0.12	0.25	≤0.008–1
Azithromycin	≤0.25	>4	≤0.25–>4	62.6/36.6	61.7/37.4
Ceftriaxone	≤0.06	1	≤0.06–8	91.3/1.2	78.0/1.2
Cefuroxime	≤0.12	8	≤0.12–>16	73.3/24.0	72.0/26.7
Clarithromycin	≤0.25	>32	≤0.25–>32	63.2/36.6	63.2/36.6
Doxycycline	0.25	8	≤0.06–>8		73.9/25.2
Erythromycin	≤0.25	>4	≤0.25–>4	62.8/36.2	62.8/36.2
Imipenem	≤0.12	0.5	≤0.12–1	79.6/4.4	100.0/0.0
Levofloxacin	1	1	≤0.5–>4	98.9/1.0	98.9/1.1
Linezolid	1	1	≤0.12–4	99.9/−	100.0/0.0
Moxifloxacin	≤0.5	≤0.5	≤0.5–>4	99.0/0.7	98.7/1.3
Penicillinb	≤0.03	4	≤0.03–>4	88.5/0.5
Penicillinc	≤0.03	4	≤0.03–>4	61.3/21.2	61.3/11.5
Tigecyclined	≤0.03	0.06	≤0.03–0.5	99.7/−
Trimethoprim-sulfamethoxazole	≤0.5	>4	≤0.5–>4	68.3/23.2	74.0/23.2
Vancomycin	0.25	0.5	≤0.12–1	100.0/−	100.0/0.0
H. influenzae (360)
BC-3781	1	2	0.015–8
Ampicillin	≤1	>8	≤1–>8	74.4/23.3	74.4/25.6
Azithromycin	1	2	≤0.25–>4	98.3/−	0.8e/1.7
Ceftriaxone	≤0.06	≤0.06	≤0.06–0.5	100.0/−	99.2/0.8
Cefuroxime	1	2	≤0.12–>16	98.6/0.6	74.4/7.5
Ciprofloxacin	≤0.03	≤0.03	≤0.03–1	100.0/−	99.7/0.3
Clarithromycin	8	16	≤0.25–>32	81.3/2.5	0.3/1.1
Doxycycline	0.5	0.5	0.12–2		98.9/0.0
Erythromycin	4	8	0.25–>8		0.3/2.8
Imipenem	0.5	1	≤0.12–4	100.0/−	99.7/0.3
Moxifloxacin	≤0.5	≤0.5	≤0.5–1	100.0/−	99.7/0.3
Tigecyclined	0.25	0.25	0.06–1	90.6/−
Trimethoprim-sulfamethoxazole	≤0.5	>4	≤0.5–>4	68.1/29.4	68.1/31.7
M. catarrhalis (253)
BC-3781	0.12	0.25	≤0.008–0.5
Azithromycin	≤0.25	≤0.25	≤0.25–2	99.6/−	99.6/0.4
Ceftriaxone	0.25	0.5	≤0.06–1	100.0/−	100.0/0.0
Cefuroxime	1	2	≤0.12–8	99.6/0.0	72.3/1.6
Ciprofloxacin	≤0.03	≤0.03	≤0.03–0.5	100.0/−	100.0/0.0
Clarithromycin	≤0.25	≤0.25	≤0.25–4	99.6/−	98.7/0.4
Doxycycline	0.12	0.25	≤0.06–4		99.6/0.4
Erythromycin	0.25	0.25	≤0.06–4	99.6/−	93.5/0.4
Imipenem	≤0.12	≤0.12	≤0.12–0.25		100.0/0.0
Moxifloxacin	≤0.5	≤0.5	≤0.5		100.0/0.0
Penicillin	>4	>4	≤0.03–>4
Tigecyclined	0.06	0.25	≤0.03–0.5
Trimethoprim-sulfamethoxazole	≤0.5	≤0.5	≤0.5–>4	94.5/2.0	94.5/3.2

^a%S, percentage of susceptible organisms; %R, percentage of resistant organisms. Criteria were as published by the CLSI (2012) and EUCAST (2011) (25, 26).

^bCriteria as published by the CLSI (2012) for “Penicillin parenteral (non-meningitis)” (25).

^cCriteria as published by the CLSI (2012) for “Penicillin (oral penicillin V)” (25).

^dU.S. FDA breakpoints were applied (Tygacil drug information) (27).

^ePercentage inhibited at ≤0.25 μg/ml (26).