TABLE 4.

Results of time-kill studies for synergy

Strain	Trovafloxacin + cefoperazone		Trovafloxacin + ceftazidime		Levofloxacin + cefoperazone		Levofloxacin + ceftazidime		Ciprofloxacin + cefoperazone		Ciprofloxacin + ceftazidime		Trovafloxacin + cefpirome		Trovafloxacin + gentamicin		Levofloxacin + cefpirome		Levofloxacin + gentamicin		Ciprofloxacin + cefpirome		Ciprofloxacin + gentamicin
	Ca	Tb	C	T	C	T	C	T	C	T	C	T	C	T	C	T	C	T	C	T	C	T	C	T
51	A	0.12/32	A	0.12/32	S	0.25/32	A	0.25/32	S	A	A	A	A	0.12/64	A	0.12/32	A	0.25/64	A	0.25/32	A	1/64	A	1/32
52	A	0.12/64	S	0.12/8	S	0.5/64	S	0.5/8	S	1/128	S	1/16	S	0.12/64	A	0.12/64	S	0.5/64	A	0.5/64	A	A	A	1/128
56	S	0.5/64	S	0.5/128	A	0.5/64	S	0.5/128	A	A	A	2/128	S	0.5/128	A	0.5/64	A	0.5/128	A	0.5/64	A	2/128	A	2/64
57	A	0.03/128	S	0.03/128	A	0.25/128	A	0.25/128	A	0.5/128	A	0.5/128	S	0.03/64	A	0.03/64	A	0.25/64	A	0.25/64	A	0.5/64	A	0.5/64
55	A	0.06/64	S	0.06/64	A	0.12/64	S	0.12/64	A	0.25/64	S	0.25/64	S	0.06/16	A	0.06/16	A	0.12/16	A	0.12/16	A	0.25/16	A	0.12/16
60	S	A	S	0.016/2	A	A	S	0.06/2	A	A	S	0.25/2	S	0.016/64	S	0.016/32	A	0.06/64	S	0.06/32	A	0.25/64	S	0.25/32
2	A	0.12/32	A	0.12/1	A	0.25/32	A	0.25/1	A	0.5/32	A	0.5/1	A	0.12/8	A	0.12/2	A	A	A	0.25/2	A	0.5/8	A	0.5/2
27	S	0.12/64	S	0.12/32	S	0.5/64	S	0.5/32	S	1/64	S	1/32	S	0.12/64	A	0.12/32	S	0.5/64	A	0.5/32	S	1/64	A	1/32
28	A	0.06/64	S	0.06/32	A	0.12/64	A	0.12/32	S	0.5/64	S	0.5/32	S	0.06/64	A	A	A	0.12/64	A	A	A	0.5/64	A	0.5/1
30	S	0.12/32	S	0.12/16	S	0.25/32	S	0.25/16	S	0.5/32	S	0.5/16	S	0.12/32	S	0.12/8	S	0.25/32	S	0.25/8	S	0.5/32	S	0.5/8
32	A	0.12/32	S	0.12/16	A	0.25/32	A	0.25/16	A	0.5/32	A	0.5/16	S	0.12/32	A	A	A	0.25/32	A	A	A	A	A	A
61	S	0.03/1	A	0.03/2	A	A	A	0.12/2	S	0.12/1	A	0.25/2	A	0.03/16	A	A	S	0.12/16	A	A	A	0.25/16	S	0.25/1
65	A	0.016/16	A	0.016/8	A	A	A	0.06/8	S	0.25/16	A	0.25/8	A	0.016/16	A	A	A	0.06/16	A	A	S	0.25/16	A	A
68	S	0.016/8	A	A	A	0.5/8	A	0.5/4	S	0.25/8	A	A	A	A	A	0.016/32	S	0.5/16	A	0.5/32	S	0.25/16	A	A
70	A	0.06/128	A	0.06/128	A	0.25/128	A	0.25/128	A	0.5/128	A	0.5/128	A	0.06/64	A	A	A	0.25/64	A	A	A	0.5/64	A	A
73	S	0.12/16	S	0.12/16	S	0.5/16	A	A	S	0.5/16	S	0.5/16	S	0.12/16	A	A	S	0.5/16	A	A	A	A	A	A
75	S	0.016/0.25	S	0.016/1	S	0.12/1	A	0.12/0.25	A	1/1	A	1/0.25	S	0.016/8	S	0.016/0.25	A	A	S	0.12/0.25	A	1/8	S	1/0.25
77	A	0.016/1	A	0.016/4	A	0.12/1	A	0.12/4	A	0.5/1	A	0.5/4	A	0.016/64	A	0.016/0.25	A	A	A	0.12/0.25	A	A	A	0.5/0.25
82	A	0.25/64	S	0.25/4	A	0.5/64	S	0.5/4	A	1/64	S	1/4	S	0.25/64	A	A	A	0.5/64	A	A	A	1/64	A	1/32
90	A	A	A	0.004/0.25	A	A	A	A	A	A	A	A	A	0.004/1	A	0.004/2	S	0.03/1	A	0.03/2	A	A	S	0.06/2

^aC, checkerboard titration; S, synergy; A, additivity or indifference. 

^bT, time-kill method; the lowest concentration (in micrograms per milliliter) of each compound in the combination yielding sustained bactericidal activity (≥100-fold decrease in viable count) at 12 h compared to the concentration (in micrograms per milliliter) of the more active drug. A, additive.