An evaluation of the antimicrobial synergy of Garlic (Allium sativum) and Utazi (Gongronema latifolium) on Escherichia coli and Staphylococcus aureus

As part of the on-going search for potent and resistance-free antimicrobial medicinal plants, the antimicrobial and synergistic effects of the plants, Allium sativum (E1) and Gongronema latifolium (E2) on Escherichia coli and Staphylococcus aureus were investigated. The sensitivities of E. coli and S. aureus to E1 and E2 and the minimum inhibitory concentrations of the plant extracts, individually and in combination with themselves, and with ciprofloxacin (CPX) and ampicillin (AMP), were tested using standard procedures. E1 and E2 individually showed appreciable antimicrobial effect (zones of inhibition > 16mm). The combination of E1 and E2 against the test organisms was not effective due to antagonism between E1 and E2. E1 or E2 when combined with CPX, completely suppressed the effect of CPX against E. coli, and rather produced additive effect on S. aureus similar to the combination of E2 and AMP against S. aureus, although CPX alone was more effective than either E1 or E2, unlike AMP. Synergism was observed in the combination of E1 and AMP against S. aureus. It is concluded that synergism associated with the combination of medicinal plants is doubtful. However, the synergistic or additive effect between garlic and conventional drugs to some strains of bacteria which are resistant to some conventional drugs, gives hope of fighting drug resistance.