Investigation of the antimicrobial effect of some natural products on Egyptian Acinetobacter baumannii isolates

Background: Extremely high mortality rates were associated with A. baumannii infections because of their resistance to first-and second-line drugs. This study aimed to investigate the antimicrobial effect of some natural products against A. baumannii. Fifty A. baumannii isolates were collected from patients at Damanhour Medical National Institute. Methods: Antibiotic resistance of isolates was determined by VITEK 2 system. Biofilm formation was detected using microtiter plate method. MIC and anti-biofilm effect of oils, liqourice and ferric chloride were determined by the broth microdilution method. RND and QS genes were detected by conventional PCR. The effect of liquorice and ferric chloride on the expression of adeB and abaI was detected using real-time PCR. Results: 72% of isolates were MDR and 86% of isolates were biofilm forming. The 4 reagents had anti-bacterial and anti-biofilm effects. 86% and 84% of isolates were positive for abaI and adeB, respectively. Liquorice and ferric chloride caused down regulation of adeB and abaI genes. Conclusion: The 4 reagents had antibacterial and anti-biofilm effects against A. baumannii isolates. Liquorice extract and ferric chloride caused down regulation of QS and efflux pump genes, and liquorice extract had a stronger effect. Therefore, it's recommended to further investigate their antibacterial effect to use them as single natural antibiotics or in combination with traditional antibiotics.