Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital- and community-acquired infections worldwide. Therefore, this study was conducted to explore the antibacterial activity of the two medicinal plants Epaltes divaricata and Vetiveria zizanioides against strains of MRSA which were isolated from patients with skin and soft tissue infections. Hexane, ethanol, and water extracts of E. divaricata (whole plant) and V. zizanioides (roots) were prepared. Clinical isolates of MRSA strains (n = 20) were used for the study. Bacterial susceptibility was tested using a disc diffusion assay. Minimum inhibitory concentration (MIC) was determined by a broth microdilution method. Vancomycin was used as the positive control. Hexane, ethanol, and water extracts of E. divaricata showed inhibitory zones against MRSA. Except for water extract, both hexane and ethanol extracts of V. zizanioides showed inhibitory zones. MIC ranges of hexane, ethanol, and water extracts in E. divaricata were 0.012–0.32 mg/mL, 0.019–2.4 mg/mL, and 0.019–0.48 mg/mL, respectively. Respective MIC ranges of hexane and ethanol extracts of V. zizanioides were 0.003–0.032 mg/mL and 0.019–2.4 mg/mL. The hexane extract of V. zizanioides inhibited 55% of the selected MRSA strains at a relatively low MIC value of 0.012 mg/mL. The hexane extract of both plants demonstrated inhibition of 75% of MRSA strains at a MIC value of 0.064 mg/mL. Ethanol extract of V. zizanioides and E. divaricata, respectively, inhibited 70% and 45% of MRSA strains at the MIC of 0.096 mg/mL, whereas water extract of E. divaricata inhibited 80% of MRSA strains at the same MIC. Both E. divaricata and V. zizanioides were equally effective against MRSA at a MIC of 0.064 mg/mL. But V. zizanioides was more effective since the hexane extract inhibited more than 50% of MRSA strains at significantly a lower MIC value of 0.012 mg/mL. Fractionation, purification, and identification of active compounds will warrant further evaluation of the therapeutic potential of both plant extracts.
Highlights
Antimicrobial resistance has become a major public health issue in the 21st century which has threatened the prevention and the treatment of a wide variety of infections caused by bacteria, viruses, and fungi. e rate of emergence of antibiotic-resistant human pathogens is greater compared to the discovery of new antibiotic drugs [1]
Disc diffusion assay was performed to detect the presence of inhibitory zones of E. divaricata and V. zizanioides against methicillin-resistant Staphylococcus aureus (MRSA)
Respective Minimum inhibitory concentration (MIC) ranges of hexane and ethanol extracts of V. zizanioides were 0.003–0.032 mg/mL and 0.019–2.4 mg/mL. e hexane extract of V. zizanioides inhibited 75% of the selected MRSA strains at relatively low MIC values ranging from 0.003 to 0.064 mg/mL. e hexane extract of E. divaricata inhibited 75% of MRSA strains at MIC values ranging from 0.012 mg/ mL to 0.064 mg/mL
Summary
Antimicrobial resistance has become a major public health issue in the 21st century which has threatened the prevention and the treatment of a wide variety of infections caused by bacteria, viruses, and fungi. e rate of emergence of antibiotic-resistant human pathogens is greater compared to the discovery of new antibiotic drugs [1]. Among the antibiotic-resistant organisms, methicillin-resistant Staphylococcus aureus (MRSA) causes a plethora of diseases involving the skin, soft tissue, bone, and joints [2]. It is one of the major causes of the hospital- and community-acquired infections [2]. MRSA infections are prevalent in Sri Lanka mainly due to prophylactic and empiric use of antibiotics [5]. It is highly prevalent in hospitals and in community samples in Sri Lanka [6]. Vancomycin is still the most commonly used antibiotic for multidrug-resistant S. aureus, but recent studies report the occurrence of S. aureus strains that are resistant to vancomycin in many countries including Sri Lanka [7]. erefore, an urge of the discovery of new drugs to combat drug-resistant microorganisms including S. aureus is essential
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