The effect of clove extract on the minimum inhibitory concentration of ciprofloxacin in fluoroquinolone resistant clinical isolates of Staphylococcus aureus

Multidrug resistant strains of Staphylococcus aureus cause serious problems worldwide. We have characterized the quinolone resistant mechanisms in clinical isolates of S. aureus and tested their susceptibilities to other classes of antibiotics. Results of this study showed high level of resistance to quinolone in the selected isolates and suggested that resistance is due to mutations in gyrA and parC genes in addition to efflux mechanism. The selected strains were not only resistant to quinolones but also found resistant to a number of other antibiotics. This study also shed some light on the possibility of using Clove as an efflux pump inhibitor. The minimum inhibitory concentration of ciprofloxacin against multidrug resistant isolates was reduced from 256 to 64 µg/ml when used in combination with Clove extract. This result indicated that Clove is a potential efflux pump inhibitor. In addition, the effect of different efflux pump inhibitors on the resistance of these isolates was determined.   Key words: Staphylococcus aureus, fluoroquinolone antibiotics, ciprofloxacin, efflux pump inhibitor, clove. .