| dc.description.abstract | The effectiveness of tetracycline antibiotics become to decline due to the threat of resistance. The combination of antibacterial compounds from natural plants with antibiotics has proven effective against many strains of bacteria. Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common resistant bacteria causing nosocomial infections. Acinetobacter baumannii is also given particular attention due to its high prevalence of resistance. Natural compounds with antibacterial activity could be considered a promising option to overcome this problem and enhance efficacy of antibiotics..
This study was conducted to investigate the antibacterial activity of Curcuma domestica rhizome and Curcuma xanthorrhiza rhizome extracts and its combination with tetracycline against MRSA and Multidrug-Resistant (MDR) A.baumannii. Both extracts were obtained by maceration. Antibacterial activity was determined by microdilution method. The combination effect with tetracycline and extracts were evaluated using checkerboard-assay. Inhibition of biofilm formation, the activity on membrane permeability, and EtBr accumulation assay also investigated.
Ethanolic extract of C. domestica (EECD) and ethanolic extract of C. xanthorrhiza (EECX) exhibited antibacterial activity against MRSA with Minimum Inhibitory Concentration (MIC) value 125 μg/mL and 250 μg/mL, and MIC value against MDR A. baumannii was 250 μg/mL and 125 μg/mL, respectively. Combination of EECD and tetracycline showed synergistic effects against MRSA and MDR A. baumannii with Fractional Inhibitory Concentration Index (FICI) value of 0.5 and 0.4. In contrast , EECX only produced an additive effect (FICI 0.6) when combined with tetracycline against MRSA but showed the synergistic effect against MDR A.baumannii with FICI value 0.3.
Furthermore, EECD and EECX enabled to inhibit the efflux pump and combination of each extract with tetracycline also inhibit biofilm formation on MRSA and MDR A. baumannii. This combination also damage the integrity of cell membrane by alteration of membrane permeability. The result of this study was revealed that both extracts increased the antibacterial activity of tetracycline and may be used as an alternative strategy to overcome MRSA and MDR A. baumanni | en_US |
