Synergistic Antibacterial Activity among Crude Extracts of Allium sativum and Citrus Limon Using Checkerboard Microdilution Method

The present study describes the synergistic antibacterial activity among crude acetone extracts of A. sativum and C. limon on clinical isolates of Staphylococcus aureus and Streptococcus pyogenes. The antibacterial activity was initially determined by the agar well diffusion method followed by determination of Minimum Inhibitory Concentration (MIC) and the synergistic effect among the two extracts using checkerboard Microdilution method. The results showed that the extract of C. limon had the highest antibacterial activity on the isolates with mean inhibition zone diameter ranging from 37.80.34 to 2.81.07 mm followed by the extract of A. sativum with mean inhibition zone diameter ranging from 24.70.8 to 0.00.0 mm. The control antibiotics, Erythromycin (10g) recorded higher antibacterial activity on S. aureus isolate than the extracts with mean inhibition zone diameter of 32.10.86mm while it had a lower antibacterial activity than C. limon extract on S. pyogenes isolate with mean inhibition zone diameter of 22.70.71mm. There was synergistic antibacterial activity among the extracts on S. pyogenes isolate at equal proportions (0.39mg/ml A. sativum and 0.39mg/ml C. limon) and when A. sativum concentration was slightly higher than C. limon in the combination (0.78mg/ml A. sativum and 0.39mg/ml C. limon). While there was no synergistic activity among the extracts on S. aureus isolate but rather an indifferent effect was observed. This study has proven the efficacy of A. sativum and C. limon extracts in inhibiting S. aureus and S. pyogenes pathogenic bacteria of clinical origin and most importantly, it has revealed the synergistic effect of the extracts against S. pyogenes pathogenic bacteria.