Antibacterial Activity of Metallic Nanoparticles against Multidrug-Resistant Pathogens Isolated from Environmental Samples: Nanoparticles/Antibiotic Combination Therapy and Cytotoxicity Study

Abstract

Multidrug-resistant organisms have increased the prevalence of infectious diseases and have become the leading source of death globally. The adverse effects associated with conventional antibiotics cannot be underestimated, and as a result, the quest for antibacterial agents has received great attention over the years. Therefore, the current research was designed to synthesize and examine the antibacterial properties of two metallic nanoparticles, silver nanoparticles (AgNPs) and zinc oxide nanoparticles (ZnONPs), as well as their antibiotic combination therapy against multidrug-resistant bacteria. AgNPs and ZnONPs were synthesized by the coprecipitation method and characterized. Thereafter, their antibacterial activity against multidrug-resistant bacteria was investigated using the microdilution technique. Subsequently, the interactions between the synthesized nanoparticles and antibiotics were evaluated by checkerboard assay. Time-kill assays were carried out to assess bacteriostatic or bactericidal effects, and the cytotoxicity study was carried out by MTT assay. The SEM analysis of AgNPs and ZnONPs were spherical with an average size of 21.03 and 43.37 nm, respectively. FTIR analysis showed the characteristics of the metal−oxygen vibrational band for both materials around 450 cm −1 , which indicated the successful synthesis of these antibacterial agents. The EDX characterization revealed Zn and O with 77.89% and 18.24% abundance in ZnONPs and Ag with 95.65% abundance in AgNPs. UV−vis absorption spectra of AgNPs was obtained around 400 nm. ZnONPs showed a moderate antibacterial effect against Enterococcus species with a MIC range of 2.5−5 mg/mL, while AgNPs demonstrated a strong antibacterial effect against the tested bacterial strains with a MIC range of 0.078−0.039 mg/mL. The ZnONPs were found to be cytotoxic against Vero cell lines at the tested concentrations, whereas AgNPs had no cytotoxic effect at lower concentrations. Their combination activities showed synergetic and additive effects. These findings revealed that these synthesized materials could serve as alternate antibacterial agents against multidrug-resistant Acinetobacter baumanni and Enterococcus species.

Synthesis and Antimicrobial Applications of ZnO Nanostructures: A Review

“…79,152,157,210−217 One of the recent research trends involves coupling ZnO NSs with other materials in order to develop hybrid systems. 205 In this regard, low-density polyethylene films, commonly used in food packaging products, were modified with ZnO NSs to develop bioactive coatings, demonstrating a considerable inhibition (>90%) against E. coli and S. aureus. 218,219 In a similar way, cross-linked pectin-based films incorporating ZnO NSs were proposed, aiming to replace the typical polymers used in food packaging industry with more biocompatible and sustainable materials.…”

“…aeruginosa, Salmonella typhimurium, K. pneumoniae, , and many others. − Some recent examples are listed in Figure .…”

“…One of the recent research trends involves coupling ZnO NSs with other materials in order to develop hybrid systems . In this regard, low-density polyethylene films, commonly used in food packaging products, were modified with ZnO NSs to develop bioactive coatings, demonstrating a considerable inhibition (>90%) against E.…”

The Potential of Antibiotics and Nanomaterial Combinations as Therapeutic Strategies in the Management of Multidrug-Resistant Infections: A Review

“…Aabed and Mohammed [ 83 ] demonstrated synergistic effects of AgNPs in combination with bacitracin, ciprofloxacin, tetracycline, and cefixime against P. aeruginosa , E. coli , S. aureus , and Candida albicans . In another study, ZnO NPs combined with Vancomycin, and ampicillin had a synergistic effect against MDR Enterococcus feacium [ 84 ].…”

“…In this respect, Lu et al [ 102 ] affirmed that the antibacterial property and particle size of AgNPs do not correlate directly but inversely. The three distinct types of AgNPs with good antibacterial activity are spherical, rod-shaped, and truncated triangular AgNPs ( Figure 2 ) [ 84 , 103 ]. The properties of these nanoparticles, which influence their activity towards bacterial pathogens, are presented in Table 1 .…”