Malik, Masrah
(2013)
In vitro antibacterial activity of Quercus Infectoria gall extracts
against multidrug resistant bacteria.
Other.
Universiti Sains Malaysia.
(Submitted)
Abstract
Antimicrobial activities of plants have long been evaluated for their potential safe remedies in the future to minimize the unwanted resistance effects of microorganisms. The study was conducted to evaluate the antibacterial activity of
Quercus infectoria gall extracts against multidrug resistance (MDR) bacterial clinical
isolates by determination of minimum inhibitory concentration (MIC) using the twofold
serial microdilution technique at concentration ranging from 5.00 mg/ml to 0.01 mg/ml
and minimum bactericidal concentration (MBC) values. Three different concentrations
(1, 2 and 5 mg/disc) of aqueous and ethanol extracts of Q. infectoria galls were used for
comparison of optimum disc concentration during screening test with five MDR
bacterial clinical isolates namely MRSA, MRCoNS, MDR Acinetobacter sp., ESBL E.
coli and ESBL K. pneumoniae. We found that, the inhibition zones diameter of 5
mg/disc were significantly larger than inhibition zones diameter of 1 mg/disc aqueous
extract against MRSA, MRCoNS and MDR Acinetobacter sp. Similarly, the significant
difference of inhibitory zone diameter was observed between 2 mg/disc and 5 mg/disc
of aqueous extract against all three isolate strains. For ethanol extract, larger inhibition
zones diameter was observed with 5 mg/disc diffusion plate of MRSA and MDR
Acinetobacter sp. as compared to 1 mg/disc diffusion plate. Among all tested bacteria,
MRCoNS was the most susceptible followed by MRSA during screening. Both extracts showed weak inhibitory effects against MDR Acinetobacter sp. while there was no inhibition zone observed for ESBLs isolates. All of the three concentrations of extracts
showed inhibition zone size which was significantly different against MRSA and at 5
mg/disc; there was a significant difference in the zone sizes between both extracts was
also observed in MRCoNS (p < 0.05). The MIC and MBC values of the extracts ranged
from 0.08 mg/ml to 2.5 mg/ml. The MIC values for aqueous and ethanol extracts against MRSA were 0.08 mg/ml and 0.16 mg/ml respectively whereas the MIC value
for both extracts against MRCoNS were the same (0.08 mg/ml). The MBC values of
aqueous extracts against MRSA and MRCoNS were above their MIC values whereas
the MBC values of ethanol extracts were the same with the MIC values against MRSA
and MRCoNS. MBC values of both extracts against all Gram negative bacteria tested
were the same with their MIC values; MDR Acinetobacter sp. (0.63 mg/ml), ESBL E.
coli (2.50 mg/ml) and ESBL K. pneumoniae (1.25 mg/ml). The Q. infectoria gall
extracts may be considered as a potentially good source of antimicrobial agents due to
the effectiveness in their in vitro antibacterial activity against MDR bacteria.
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