Regulation of overexpressed efflux pump encoding genes by cinnamon oil and trimethoprim to abolish carbapenem-resistant Acinetobacter baumannii clinical strains.

Resistance mechanisms are a shelter for Acinetobacter baumannii to adapt to our environment which causes difficulty for the infections to be treated and WHO declares this organism on the top of pathogens priority for new drug development. The most common mechanism that develops drug resistance is the overexpression of the efflux pump, especially Resistance-nodulation-cell division (RND) family, to almost most antibiotics. The study is designed to detect RND efflux pump genes in A. baumannii, and its correlation to multidrug resistance, in particular, the carbapenems resistance Acinetobacter baumannii (CRAB), and using different inhibitors that restore the antibiotic susceptibility of imipenem. Clinical A. baumannii isolates were recovered from different Egyptian hospitals in Intensive care unit (ICU). The expression of genes in two strains was analyzed using RT-PCR before and after inhibitor treatment. About 100 clinical A. baumannii isolates were recovered and identified and recorded as MDR strains with 75% strains resistant to imipenem. adeB, adeC, adeK, and adeJ were detected in thirty- seven the carbapenems resistance Acinetobacter baumannii (CRAB) strains. Cinnamomum verum oil, Trimethoprim, and Omeprazole was promising inhibitor against 90% of the carbapenems resistance Acinetobacter baumannii (CRAB) strains with a 2-6-fold decrease in imipenem MIC. Downregulation of four genes was associated with the addition of those inhibitors to imipenem for two the carbapenems resistance Acinetobacter baumannii (CRAB) (ACN15 and ACN99) strains, and the effect was confirmed in 24 h killing kinetics. Our investigation points to the carbapenems resistance Acinetobacter baumannii (CRAB) strain's prevalence in Egyptian hospitals with the idea to revive the imipenem activity using natural and chemical drugs as inhibitors that possessed high synergistic activity.