Antibacterial and Antibiofilm Activities of Nonpolar Extracts of Allium stipitatum Regel. against Multidrug Resistant Bacteria

Table 1

Zone of inhibition, MIC, and MBC of ASHE and ASDE against test microorganisms (20 μL corresponding to 200 μg/disc).

Strain	Zone of inhibition in diameter (mm)^a				MIC (g mL^-1)^b		MBC (g mL^-1)^c
	ASHE	ASDE	Antibiotic	DMSO (10)	ASHE	ASDE	ASHE	ASDE
Gram-positive bacteria
MRSA	27 ± 0.5774	23 ± 0.2887	16 (VA)^d	-	32	64	128	128
MSSA	26 ± 0.2887	30 ± 0.5774	30 (VA)	-	64	16	128	64
Vancomycin resistant enterococci	13 ± 0.7638	15 ± 0.8660	33 (TOB)^e	-	512	1024	2056	4096
Gram-negative bacteria
Acinetobacter baumannii	26 ± 0.2887	28 ± 0.0	33 (IPM)^f	-	32	32	64	32
A. lwoffii	33 ± 0.5774	30 ± 0.2887	46 (IPM)	-	16	32	32	32
Enterobacter spp.	14 ± 0.2887	16 ± 0.5774	23 (MEM)^g	-	512	1024	2056	4096
Escherichia coli	21 ± 0.2887	29 ± 0.5774	16 (AK)^h	-	128	32	512	128
Klebsiella pneumoniae	20 ± 0.0	29 ± 0.5000	- (AK)	-	256	64	512	256
Pseudomonas aeruginosa	13 ±0.5774	15 ± 0.2887	23 (CAZ)^i	-	1024	1024	2056	4096
Salmonella typhi	20 ± 0.5000	32 ± 0.5000	25 (CIP)^j	-	256	32	256	128
Shigella dysenteriae	18 ± 0.7638	22 ± 0.5000	27 (CTX)	-	256	128	1024	1024
Stenotrophomonas maltophilia	26 ± 0.5774	27 ± 1.000	30 (SXT)^k	-	64	64	256	256

Determined by disk diffusion assay.
^bDetermined by broth microdilution method.
^cDetermined by plate colony count technique.
^dVancomycin (30 μg).
^eTobramycin (10 μg).
^fImipenem (10 μg).
^gMeropenem (30 μg).
^hAmikacin (30 μg).
ⁱCeftriaxone (10 μg).
^jCiprofloxacin (5 μg).
^kTrimethoprim-sulfamethoxazole (30 μg).
-: no zone of inhibition.
Preliminary antibacterial data for ASHE/ASDE on MRSA (disk diffusion and MIC values) has been published recently by our research group (Karunanidhi et al., 2017).