Table 2.

Antimicrobial Susceptibilities of 52 Elizabethkingia Isolates Determined by the Broth Microdilution Method

Antimicrobial Agents	Breakpoint (mg/L)			MIC (mg/L)			Number (%) of Isolates
S	I	R	Range	50%	90%	S	I	R
Piperacillin	≤16	32–64	≥128	8 to >128	32	64	24 (46.2)	23 (44.2)	5 (9.6)
Piperacillin-tazobactam	≤16/4	32/4–64/4	≥128/4	0.25/4 to >128/4	4/4	32/4	45 (86.5)	7 (13.5)	0 (0.0)
Cefoperazone	≤16	32	≥64	16 to >128	32	>128	3 (5.8)	25 (48.1)	24 (46.2)
Cefoperazone-sulbactam	≤16/8	32/16	≥64/32	2/1–128/64	8/4	64/32	46 (88.5)	1 (1.9)	5 (9.6)
Ceftazidime	≤8	16	≥32	64 to >128	>128	>128	0 (0.0)	0 (0.0)	52 (100.0)
Cefepime	≤8	16	≥32	16 to >128	32	>128	0 (0.0)	8 (15.4)	44 (84.6)
Aztreonam	≤8	16	≥32	>128	>128	>128	0 (0.0)	0 (0.0)	52(100.0)
Imipenem	≤4	8	≥16	8 to >128	16	128	0 (0.0)	6 (11.5)	46 (88.5)
Meropenem	≤4	8	≥16	8 to >128	32	>128	0 (0.0)	4 (7.7)	48 (92.3)
Colistin	≤2	–	≥4	>128	>128	>128	0 (0.0)	0 (0.0)	52 (100.0)
Amikacin	≤16	32	≥64	16 to >128	64	>128	4 (7.7)	3 (5.8)	45 (86.5)
Gentamicin	≤4	8	≥16	4 to >128	64	>128	1 (1.9)	1 (1.9)	50 (96.2)
Ciprofloxacin	≤1	2	≥4	0.25 to >128	1	128	26 (50.0)	6 (11.5)	20 (38.5)
Levofloxacin	≤2	4	≥8	0.25–64	1	32	37 (71.2)	1 (1.9)	14 (26.9)
Rifampin	≤1	2	≥4	0.5–64	1	8	40 (76.9)	6 (11.5)	6 (11.5)
Trimethoprim-sulfamethoxazole	≤2/38	-	≥4/76	1/19–16/304	4/76	8/152	19 (36.5)	0 (0.0)	33 (63.5)
Tigecycline	≤2	4	≥8	1–32	4	8	41 (78.8)	8 (15.4)	3 (5.8)
Doxycycline	≤4	8	≥16	1–8	2	4	50 (96.2)	2 (3.8)	0 (0.00)
Minocycline	≤4	8	≥16	0.25–4	0.5	1	52 (100.0)	0 (0.0)	0 (0.0)
Vancomycin	≤4	8–16	≥32	8–32	16	16	0 (0.0)	12 (23.1)	40 (76.9)
Linezolid	≤4	-	≥8	4–128	16	32	2 (3.8)	0 (0.0)	50 (96.2)

Notes: In the combinations, the concentration of tazobactam was 4 mg/L constant. The ratio of cefoperazone to sulbactam was 2:1, and the ratio of trimethoprim to sulfamethoxazole was 1:19.

Abbreviations: MIC, minimal inhibitory concentration; S, susceptible; I, intermediate; R, resistant.