The Antibacterial Effect of Spices against Streptococcus pyogenes and Klebsiellapneumoniae

In order to subvert the resistance being developed by microbes to popular antibiotics new sources of antibacterial agents of plant origins are considered. Ethanol extracts of 10 different spices Sesamum indicum (sesame),Papaver somniferum (poppy), Foeniculum vulgare (fennel), Trigonella foenumgraecum(fenugreek), Coriandrum sativum (coriander), Cuminum cyminum (cumin), Piper nigrum (black pepper), Cinnamomum zeylanicum (cinnamon), Syzygium aromaticum (cloves) and Illicium verum (star anise) were tested using the well diffusion method for the antibacterial effect against a gram-positive bacterium Streptococcus pyogenes anda gram-negative bacterium Klebsiella pneumoniae.

 The antibacterial effect of spices was analyzed by measuring the zone of inhibition which indicates the effectiveness of the spices against the bacteria. Positive controls (erythromycin and ciprofloxacin) were used to compare the effect of the spice extracts. Sesame, poppy and fenugreek showed no antibacterial effect against both the bacteria whereas the other spices have antibacterial effects.

The most effective spices in inhibiting the growth of S. pyogenes were cinnamon and cloves which showed a low Minimum Inhibitory Concentration (MIC) of 5% which was 0.045 gmL^-1 and 0.049 gmL^-1 respectively. The growth of K. pneumoniae was effectively inhibited by cinnamon and star anise. The MIC for both of the spices was 40%, with a conc. 0.360 g mL^-1