TABLE 2.

Time-kill assay results^a

Drug and concn	No. of strains
	6 h			12 h			24 h			48 h
	−1b	−2b	−3b	−1	−2	−3	−1	−2	−3	−1	−2	−3
Ertapenem
4× MIC	10	7	5	10	10	7	10	9	8	10	9	9
2× MIC	10	7	4	10	9	6	10	9	8	10	9	9
MIC	10	6	2	10	9	6	9	8	7	9	8	8
Imipenem
4× MIC	9	7	5	10	10	7	10	10	8	10	10	9
2× MIC	9	7	5	10	8	7	10	10	8	10	10	9
MIC	9	7	4	10	8	7	10	10	8	10	10	9
Meropenem
4× MIC	9	7	1	10	9	6	10	10	10	10	10	10
2× MIC	8	4	0	10	9	5	10	10	9	10	10	10
MIC	8	4	0	10	7	3	8	8	4	6	6	5
Ceftriaxone
4× MIC	10	7	4	10	9	8	10	10	9	10	10	10
2× MIC	10	6	3	10	9	7	10	10	9	10	10	10
MIC	9	5	0	10	8	6	9	9	8	9	8	8
Piperacillin
4× MIC	9	8	6	10	8	8	10	9	8	10	9	9
2× MIC	9	8	4	10	8	8	10	9	8	10	9	9
MIC	9	7	2	10	8	6	10	9	7	9	8	8
Piperacillin-tazobactam
4× MIC	9	6	3	10	9	7	10	9	9	10	9	9
2× MIC	8	4	2	10	9	7	10	9	9	10	9	9
MIC	7	2	1	10	6	4	10	8	7	9	6	5
Clindamycin
4× MIC	5c	1c	0c	9	5c	1c	10	9	4	10	10	8
2× MIC	5c	1c	0	9	5	1c	10	8	4	10	10	8
MIC	5c	0c	0	8	4c	1c	7	4	1	6	6	4
Metronidazole
4× MIC	10	9	7	10	10	9	10	10	9	10	10	9
2× MIC	10	9	4	10	10	9	10	9	8	10	8	7
MIC	10	7	2	10	10	7	10	7	7	9	5	5

^aStrains tested: B. fragilis (2), B. thetaiotaomicron (1), P. bivia (1), Prevotella disiens (1), F. nucleatum (1), Fusobacterium mortiferum (1), Peptostreptocccus asaccharolyticus (1), C. perfringens (1), and C. difficile (1).

^bLog₁₀ CFU per milliliter decrease in colony count compared to time zero at indicated time (−1 = 90% killing; −2 = 99% killing; −3 = 99.9% killing).

^cProportions of strains at different extents of killing are significantly less (P < 0.05) than observed with ertapenem.