Combined antibacterial activity of eucalyptol, γ-terpinene, p-cymol and punicalagin with cefotaxime against methicillin (Oxacillin) resistant Staphylococcus aureus isolate

Resistance to antibiotics is a significant public health issue in preventing infectious diseases. This study was designed to evaluate the antibacterial activity of eucalyptol, γ-terpinene, p-cymol and punicalagin against Methicillin (Oxacillin) resistant strains. The synergistic effect of these compounds with cefotaxime against Staphylococcus aureus was investigated. The lowest MIC value observed was 0.08mg/mL for punicalagin against S. aureus, followed by the MIC values of punicalagin against E. aerogenes, E. coli and K. pneumoniae (0.16 - 0.63mg/mL). The activity of p-cymol against S. aureus is ranked second, as indicated by the MIC value (0.63mg/mL). The results of the combination study showed that the maximum Increase in Folding Area (IFA) was reported when punicalagin was combined with cefoxitin, cefotaxime, oxacillin, and piperacillin. An effective IFA was observed when p-cymol was tested with piperacillin, cefixime, cefotaxime, oxacillin, and cefoxitin. Based on the checkerboard assay, the MIC of cefotaxime decreased from 60 to 7.5μg/mL when combined with punicalagin indicating a significant synergistic effect between cefotaxime and punicalagin against S. aureus. In conclusion, punicalagin improved S. aureus susceptibility to cefotaxime, suggesting that using these two medicines together can reverse beta-lactam resistance in methicillin (oxacillin) resistant S. aureus. Further works are required to generalize this result and then it may be useful for treating diseases caused by methicillin (oxacillin) resistant strains.