Inhibition of antibiotic-resistant Staphylococcus aureus using the combined application of cumin essential oil and norfloxacin

This study was carried out to evaluate the combined anti-staphylococcal effect of cuminessential oil with norfloxacin. The oil was analyzed using GC and GC-MS. Cuminaldehyde was the most abundant (21.27%) constituent. The microdilution broth assaywas applied to determine minimum inhibitory concentrations (MICs). The standardmethicillin sensitive strain of Staphylococcus aureus (MIC = 198 Μg/ml) and themethicillin resistant clinical isolates of Staphylococcus aureus (MIC= 264-396 μg/ml)were the most sensitive and resistant organisms against the essential oil, respectively.The combined application of the essential oil and norfloxacin against methicillinsensitive or resistant Staphylococcus aureus was decreased significantly whencompared to their single application. The fractional inhibitory concentration indices(FICIs) indicated the synergism phenomenon (FICIs = 0.37-0.5) between the essentialoil and norfloxacin against the methicillin resistant isolates. In addition, theantimicrobial interactions against the methicillin sensitive Staphylococcus aureus wereadditive (FICI = 0.62). The results showed that the used antimicrobial combinationcould be considered as an appropriate alternative instead of synthetic antimicrobialagents.