The efficacy of calendula officinalis tincture as a local antimicrobial agent

The purpose of this in-vitro study was to determine the efficacy, with respect to the antimicrobial properties, of Calendula officinalis tincture prepared in 30% ethanol and 60% ethanol respectively, as compared with a control of 30% ethanol and 60% ethanol respectively, upon Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus pyogenes; in order to contribute towards the understanding of the use of Calendula officinalis tincture in infections caused by these bacteria. The hypothesis put forward was that Calendula officinalis tincture would have an inhibitory effect on the growth of each of these bacteria. The method utilised to evaluate the antimicrobial activity of Calendula officinalis tincture in this research was a modification of the Kirby-Bauer Antimicrobial Sensitivity Test. Two replicate groups of media were tested, Group A being the group containing the Calendula officinalis tincture in 30% ethanol and the 30% ethanol control; and Group B exposed to the tincture in 60% ethanol and the 60% ethanol control. Group A contained 12 inoculated plates, two plates with each type of bacteria being tested, one labelled as the test subgroup and the other as the control subgroup. Thus, each subgroup consisted of 6 media plates each containing a different culture of bacteria. Each plate in the test subgroup was then exposed to discs immersed in the Calendula officinalis tincture prepared in 30% ethanol, as described in the procedure below, while each plate in the control subgroup was exposed to discs immersed in 30% ethanol only. This procedure was repeated for Group B but Calendula officinalis tincture prepared in 60% ethanol was used for the test subgroup, and 60% ethanol only was used for the control subgroup