Synergistic effect of ethanolic extract of melastoma malabataricum leaves and antibiotics

Abstract

Combination therapies for the treatment of bacterial infections can slow down the development of resistance. This study was carried out to study the synergistic effect of ethanolic extract of Melastoma malabathricum (MM) leaves and antibiotics on growth of pathogenic bacteria: Salmonella, E. coli, S. aureus & S. pyogenes. Kirby-Bauer disk diffusion method and broth micro dilution were used to study the antimicrobial susceptibility, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC).Only gram positive bacteria was susceptible to the extract. MIC and MBC of the ethanolic extract with concentration 6.25 mg/mL for S. aureus and 12.5 mg/mL for S. pyogenes. Data analysis using ANOVA and Least Significant Difference (LSD) showed that there was a significant increase in the diameter of the zone of inhibition with combined application with tetracycline (p=5.99E-12, p<0.05) and chloramphenicol (p=4.25E-6, p<0.05) when compared to the antibiotic control. For S. pyogenes, only chloramphenicol showed significant increase in zone of inhibition when combined with extract (p=5.63E-7, p<0.05). These results suggest that the combination of MM extract with certain antibiotics may be useful in the fight against resistance in gram positive bacteria.