In Vitro Synergism of Silver Nanoparticles with Antibiotics as an Alternative Treatment in Multiresistant Uropathogens

Abstract

The increase in the prevalence of bacterial resistance to antibiotics has become one of the main health problems worldwide, thus threatening the era of antibiotics most frequently used in the treatment of infections. The need to develop new therapeutic strategies against multidrug resistant microorganisms, such as the combination of selected antimicrobials, can be considered as a suitable alternative. The in vitro activities of two groups of conventional antimicrobial agents alone and in combination with silver nanoparticles (AgNPs) were investigated against a set of ten multidrug resistant clinical isolate and two references strains by MIC assays and checkerboard testing, as well as their cytotoxicity, which was evaluated on human fibroblasts by MTT assay at the same concentration of the antimicrobial agents alone and in combination. Interesting results were achieved when the AgNPs and their combinations were characterized by Dynamic Light Scattering (DLS), Zeta Potential, Transmission Electron Microscopy (TEM), UV–visible spectroscopy and Fourier Transforms Infrared (FTIR) spectroscopy. The in vitro activities of ampicillin, in combination with AgNPs, against the 12 microorganisms showed one Synergy, seven Partial Synergy and four Additive effects, while the results with amikacin and AgNPs showed three Synergy, eight Partial Synergy and one Additive effects. The cytotoxic effect at these concentrations presented a statistically significant decrease of their cytotoxicity (p < 0.05). These results indicate that infections caused by multidrug resistant microorganisms could be treated using a synergistic combination of antimicrobial drugs and AgNPs. Further studies are necessary to evaluate the specific mechanisms of action, which could help predict undesirable off-target interactions, suggest ways of regulating a drug’s activity, and identify novel therapeutic agents in this health problem.

Evaluation of antibacterial activity of silver nanoparticles against multidrug-resistant Gram negative bacilli clinical isolates from Zagazig University Hospitals

“…The recorded MICs values of AgNPs in the current study come very close to the values reported previously [18] when AgNPs of an average size of 8.23 nm ± 0.91 nm were tested against MDR uropathogens including E.coli, Klebsiella, P.aeruginosa and Acinetobacter isolates with MIC values of (8, 4, 8 and 16 µg/ml). Higher MIC values of 31.25µg/ml and 62.5µg/ml were reported [19] on using 11-21 nm AgNPs against E.coli and Klebsiella pneumoniae, respectively.…”

“…A previous study [18] strongly supports the obtained results recording a synergistic effect of AgNPs of 8.23 nm size and at concentration of 4-16 µg/ml where a decrease in the MIC of amikacin by 16, 2, 8, 32 folds against E.coli, Klebsiella, P.aeruginosa and Acinetobacter isolates were recorded. These findings locate within our recorded ranges against the same isolates respectively (2-16, 2-16, 2-32 and 8-32).…”

Antimicrobial effects of cinnamon essential oil and cinnamaldehyde combined with EDTA against canine otitis externa pathogens

“…The results indicate synergism when the corresponding FICI ≤ 0·5, addition when 0·5 < FICI ≤ 1, indifference when 1 < FICI ≤ 4 and antagonism when the FICI > 4 (Lopez‐Carrizales et al . ).…”

The Demand for New Antibiotics: Antimicrobial Peptides, Nanoparticles, and Combinatorial Therapies as Future Strategies in Antibacterial Agent Design

“…Among the most studied nanomaterials are silver nanoparticles due to their antimicrobial activity against Gram-positive and Gram-negative bacteria. They can be used in combinatorial treatments with currently used antibiotics for enhanced antimicrobial activity (Shahverdi et al, 2007;Kora and Rastogi, 2013;Naqvi et al, 2013;Singh et al, 2013;Panácek et al, 2016;Lopez-Carrizales et al, 2018;Perveen et al, 2018;Vazquez-Muñoz et al, 2019). Nonetheless, some other MNPs FIGURE 2 | Antimicrobial treatment strategies: (A) disadvantages of using single drugs and (B) advantages of using combinatorial treatments.…”