Evaluation of antimicrobial effect ZnO nanoparticles and Clove extract against Pseudomonas aeruginosa isolated from clinical samples

Introduction

The emergence of multidrug-resistant pathogens leads to treatment failure. So, the need for new antibacterial drugs is urgent. We evaluated the antibacterial and antibiofilm effects of zinc oxide (ZnO) nanoparticles (NPs) and clove extract against biofilm-producing Pseudomonas aeruginosa.

Materials and methods

In this descriptive-experimental study, clinical isolates of P. aeruginosa were collected d from different wards of Shahid Beheshti Hospital in Kashan. In this research, the extract of clove was obtained by the Soxhlet extraction method in concentrations of 250 mg/ml to 62.5 mg/ml. ZnO nanoparticles were chemically synthesized at Kashan University of Medical Sciences in 125–250 µg/ml concentrations. We evaluated the antibacterial and antibiofilm effects of ZnO/NPs and clove extract against biofilm-producing Pseudomonas aeruginosa microbroth dilution and crystal violet assays. The combined effect of these compounds was studied using the checkerboard method. The expression of biofilm-related gene (algD) was investigated by real-time PCR.

Findings

The MIC values of the compounds tested for P. aeruginosa were estimated at 312.5, 1250, and 78.12 μg/ml. Also, ZnO/NPs and clove extract and their combination. In this study the result showed that, the combination of Zno/NPs and clove extract resulted in the decrease in MIC/MBC for P. aeruginosa. The FICI classified the combination of combination of Zno/NPs and clove extract as synergistic for P. aeruginosa. According to the results, a combination of ZnO/NPs and clove extract at a concentration of 2MIC strongly inhibited the biofilm formation up to 60 % after 24 h. Moreover, treatment with combination of ZnO/NPs and clove extract led to the downregulation of the AlgD gene expression, a key factor in biofilm formation.

Conclusion

Collectively, the combination of ZnO-NPs and clove extract improved antibacterial properties due to changes in the surface of nanoparticles. In addition, based on the present study, the effective combination Zno/NPs and clove extract could be employed as a natural antibacterial agent against.