Time-kill kinetics and antibacterial activity of ethanolic extract of Allium sativum

Abstract

Background: Allium sativum (A. sativum) has been known to possess various medicinal properties, including antibacterial activity. Aim: This study was designed to evaluate and quantify killing kinetics of A. sativum. Methods: Allium sativum in vitro time-kill kinetics antibacterial investigation was evaluated by plate count technique and analyzed by percentage and log reduction against Pseudomonas aeruginosa and Staphylococcus aureus. An ethanolic extract of A. sativum was prepared and tested against Pseudomonas aeruginosa and Staphylococcus aureus. The kinetics of killing and re-growth of the bacteria were then assessed as functions of both time and the extract concentration. Results: The time kill-kinetics of Allium sativum ethanol extract against the test organisms showed that the extract achieved 100% killing at 1 mg/ml against the two test organisms after 12 h of contact. All test organisms were susceptible to ethanolic extract. Average log reductions in viable cell counts for the extract ranged between 0.02log10 and 1.20log10 cfu/ml for P. aeruginosa and 0.03log10 and 0.97log10 cfu/ml for S. aureus after 10 h interaction at 0.5mg/ml and 1mg/ml. The extract was rapidly bactericidal at 1mg/ml achieving a complete elimination of the two test organisms within 12 h exposure. Conclusion: Overall, this quantified information on time-kill kinetics may provide an initial step towards understanding in vitro pharmacodynamics of antibacterial activity of A. sativum.