Evaluation of Antibacterial Activity of Lemongrass Oil Against Oral Clinical Isolates – An In vitro Study

Background: There are 1,200 oral species out of which 400 are potentially important and 20 organisms are periopathic. Periodontal flora plays the important role in initiation and progression of periodontal diseases. There are various conservative and surgical procedures to treat and prevent periodontal diseases. Local drug delivery agents reduce microbial burden, blocks collagenase activity and inhibits bone loss; out of which tetracycline is common in use. Unwanted side effects and resistance of microorganisms towards antibiotics due to their widespread use have modified the general prescription about their efficacy. Various researches elucidate that herbal extracts exhibit wide range of antibacterial activity. In recent years, Lemongrass essential oil gains scientific interest as it targets even the periodontal pathogens. The purpose of this study is to comparatively evaluate the antibacterial activity of lemongrass essential oil with that of tetracycline. Aim and objective: To comparatively evaluate the antibacterial activity of lemongrass essential oil with tetracycline against Streptococcus mutans, Staphylococcus epidermidis and Lactobacillus and to determine the minimal inhibitory concentration of lemongrass essential oil. Study design: In vitro. Materials and Methods: It is an in vitro study done to demonstrate the antimicrobial activity of lemongrass against the oral microbes. Based on their involvement in various clinical conditions Streptococcus mutans, Staphylococcus epidermidis and Lactobacillus were selected for the study. These organisms were inoculated to a solid media and incubated overnight aerobically at 37°C to obtain a pure culture. The culture was made as a suspension in sterile saline with the turbidity matching 0.5 Macfarland standard. This is used to make a lawn culture on the Mueller Hinton Agar. Antimicrobial effect of tetracycline was tested using standard disc of doxycycline 30 mcg (Himedia, SD012) and sterile disc was used to prepare lemongrass essential oil which contained 10 μl, 15 μl and 20μl. In each category 5 discs were tested to get a mean zone of inhibition. After 24 hours of incubation the zone of inhibition was measure in mm using a scale. The measured zone size was tabulated and compared among the groups. Results: The minimal inhibitory concentration of lemon grass essential oil was estimated to be 10μl. Statistically significant zone of inhibition and antibacterial zone was greater in lemongrass essential oil than tetracycline for Streptococcus mutans and Staphylococcus epidermis. Conclusion: Lemongrass essential oil showed higher antibacterial activity than tetracycline. Hence, it can be used as a good alternative to tetracycline or adjunctive in the treatment of periodontitis.