An Efflux Pumps Inhibitor Significantly Improved the Antibacterial Activity of Botanicals from Plectranthus glandulosus towards MDR Phenotypes
Table 3
MICs (μg/mL) of extract, active fractions of P. glandulosus and chloramphenicol in the presence of PAβN.
Bacteria
Tested samples, MIC in the presence of PAβN (AMFs) (μg/mL)
Extract
Fraction C
Fraction D
Chloramphenicol
Escherichia coli
ATCC 8739
<8 (nd)
<4 (>8)
<4 (>16)
<2 (nd)
AG 102
<8 (nd)
8 (32)
<4 (>64)
8 (4)
Enterobacter aerogenes
ATCC 13048
32 (nd)
64 (2)
256 (2)
32 (1)
EA 27
<8 (nd)
<4 (>64)
32 (16)
16 (1)
Klebsiella pneumoniae
ATCC 11296
<8 (nd)
<4 (>64)
<4 (128)
8 (1)
KP 55
32 (nd)
32 (2)
64 (8)
32 (1)
Providencia stuartii
ATCC 29916
<8 (nd)
64 (4)
256 (2)
8 (8)
PS 2636
512 (nd)
<4 (64)
256 (2)
16 (4)
Pseudomonas aeruginosa
PA 01
<8 (nd)
>512 (nd)
>512 (nd)
8 (8)
PA 124
256 (nd)
64 (4)
512 (1)
16 (4)
MIC, minimum inhibitory concentration; nd, not determined. Activity modulation factors (AMFs) were determined to qualify the potentiation level of sample activity in the presence of EPI. All assays were performed in triplicate and repeated thrice. In bold are AMF ≥ 4.
