Antibacterial potential of indigenous medicinal plants against methicillin-resistant Staphylococcus aureus isolated from septic wounds

Aims: This study was aimed to screen indigenous medicinal plants for their antibacterial potential against methicillin-resistant Staphylococcus aureus (MRSA). Methodology and results: Three indigenous plants (Nigella sativa, Zingiber officinale and Calotropis procera) and thymoquinone were screened for antibacterial activity against MRSA, isolated from septic wounds of patients admitted to Mayo Hospital Lahore, Pakistan. Isolated bacteria were screened for methicillin and cefoxitin resistance by the KirbyBauer method, followed by mecA gene-specific polymerase chain reaction (PCR). Confirmed MRSA was processed for antibacterial activity of plant extracts and thymoquinone followed by cytotoxicity assay of plant extract having least minimum inhibitory concentration (MIC) value. Out of total samples (n=100), S. aureus (29%), MRSA (26%) and vancomycin-resistant S. aureus (VRSA) (21.7%) isolates were recovered based on morphology, biochemical profile and antibiotic susceptibility testing. Nigella sativa showed the highest antibacterial activity (10.06 +/- 6.53 mm) against MRSA followed by Z. officinale (4.06 +/- 3.72 mm) and C. procera (3.65 +/- 3.33 mm) in comparison to standard thymoquinone (17.93 +/- 10.14 mm). The least MIC value recorded was for Z. officinale at 36.89 +/- 3.75 mu g/mL. Zingiber officinale was the most effective antibacterial agent, followed by N. sativa and C. procera and non-toxic for eukaryotic cells at all tested concentrations (1500 mu g/mL to 2.92 mu g/mL). Conclusion, significance and impact of study: It was concluded that Z. officinale may be used as an effective alternative for treating septic wound infection in local or topical preparations. As pathogenic S. aureus is becoming life-threatening among antibiotic-resistant bacteria and traditional plants are in used for centuries to treat septic wound infections.