In Vitro Synergy of Levofloxacin Plus Piperacillin/Tazobactam against Pseudomonas aeruginosa

Table 1

Etest MIC (𝜇g/mL), Etest Synergy Method, and Time-Kill Assay.

P. aeruginosa
𝑛=31	LVX MIC	TZP MIC
	Etest^(a)	Etest^(a)
1	> 32	> 256
2	8	> 256
3	32	> 256
4	> 32	> 256
5	> 32	4
6	> 32	16
7	> 32	4
8	> 32	> 64
9	32	> 4
10	> 32	> 4
11	> 32	> 256
12	> 32	> 256
13	> 32	> 256
14	> 32	> 256
15	> 32	> 256
16	> 32	> 256
17	> 32	16
18	> 32	> 256
19	> 32	> 256
20	> 32	> 256
21	> 32	32
22	> 32	> 256
23	> 32	32
24	> 32	16
25	> 32	> 256
26	> 32	32
27	> 32	> 256
28	> 32	8
29	> 32	> 256
30	> 32	> 256
31	> 32	> 256

*Pseudomonas aeruginosa strains with discordant synergy results. ^(a)Performed in triplicate. ^(b)Values represent the log₁₀ change in CFU/mL in the time-kill assay after 24 hour exposure to the combination of levofloxacin (LVX) and piperacillin/tazobactam (TZP) compared to the most active drug alone. Negative values indicate a decrease in colony count; positive values indicate an increase in colony count. S: synergy; I: indifference.