Silver nanoparticles potential as an adjuvant in antimicrobial therapies against multidrug resistant bacteria

Maryam Abbasi shaye,1,* Mohammad reza sharifmoghadam,2

1. Department of Biology, Faculty of Science, Ferdowsi University of Mashhad
2. Department of Biology, Faculty of Science, Ferdowsi University of Mashhad



The emergence and rapid spread of multidrug-resistant (mdr) isolates of pathogenic bacteria causing nosocomial infections is a worldwide nightmare which is mainly due to increasing and indiscriminate use of antibiotics. therefore, searching for effective antibiotic substitutes or novel factors as adjuvants for combination therapy is of great importance. silver is a safe inorganic antibacterial agent, which is capable of killing many pathogenic microorgainsms. silver nanoparticles(agnps) in particular have drawn special attention because they were found to be effective even against mdr organisms. the aim of this study was to investigate antimicrobial capacity of biosynthesized agnps alone and in combination with conventional antibiotics against pathogenic bacteria.


Determination of minimum inhibitory concentration(mic) of agnps and tested antibiotics, ampicillin, ceftriaxone and ciprofloxacin, and also synergy tests were carried out for mdr isolates of acinetobacter baumannii, escherichia coli and klebsiella pneumoniae using a standard twofold broth microdilution method. fractional inhibitory concentration(fic) index was also determined for each combination test.


Fic results showed synergistic effects of agnps and ampicillin against k.pneumoniae and a. baumannii. it also showed a synergistic effect of agnps and ceftriaxone against e. coli. additive effects of agnps and the antibiotics were observed in other combinations.


In conclusion, this study presented evidence of the antibacterial effects of agnps and their potential as an effective agent for combination therapy against different pathogens.


Silver nanoparticles, antibiotic resistance, a.baumannii, e. coli, k.pneumoniae