Novel Microdilution Method to Assess Double and Triple Antibiotic Combination Therapy In Vitro

Table 2

Susceptibility of Pseudomonas aeruginosa clinical isolates to the antibiotics.

Isolate number	Antibiotics (g/mL)
	CIP		AMK		CAZ		PIP		IMP
	MIC	MBC	MIC	MBC	MIC	MBC	MIC	MBC	MIC	MBC
PA2	0.125	0.125	2	8	1	4	8	8	2	>32
PA3	0.125	0.125	2	8	8	16	16	>128	>	>32
PA9	0.5	1	4	32	8	8	8	16	2	8
PA11	>	>16	8	16	>	>32	>	>128	>	>32
PA14	2	8	2	16	4	32	32	32	2	>32
PA15	0.125	0.125	4	16	4	16	8	32	4	>32
PA18	0.031	0.06	2	8	2	2	8	128	8	>32
PA19	0.06	0.125	2	2	2	4	8	32	4	>32
PA20	>	>16	4	16	>	>32	>	>128	>	>32
PA21	0.125	0.25	2	8	4	4	8	32	8	>32

(i) The MIC is the minimum inhibitory concentration; MBC is defined as the concentration required to kill 99.9% of the bacteria.
(ii) The MICs of the tested antibiotics were determined by broth microdilution method.
(iii) The R letter denotes resistance of the isolate to the antibiotic based on the EUCAST MIC breakpoint guideline [21].
(iv) CIP, ciprofloxacin; AMK, amikacin; CAZ, ceftazidime; PIP, piperacillin; IMP, imipenem.