The effect of silver nanoparticles on Gram-negative bacilli Resistant to Extended-Spectrum

Background and objectives: Antibiotic resistant to Antimicrobial agents isone of the most important concerns in hospitals, which can lead toincreased costs, treatment fails and mortality rates. The aim of this studywas identification of Gram-negative bacilli resistant to extended-spectrumβ-lactamase Enzymes (ESBLs) and determination of the effect of silvernanoparticles on them.Materials & Methods: Of 276 clinical samples referred to three hospitalsof Isfahan city, 186 gram negative bacilli were studied. To recognizeESBLs production, the bacilli was assessed by disk diffusion method andconfirmed by DDT and Double Disk approximation Test. The ESBLproducing bacteria were subjected to increasing concentrations (12.5, 25,50,100,200,400 and 500 ppm) of silver nanoparticles, prepared in TehranNano Pars Company, and Inhibitory zone diameter was measured.Results: Of 186 isolates, 140 (%75/3) are gram-negative bacilli producingESBLs and 46 (24.7%) of them without this capability. Most of ESBLsbacteria are belonged to urine infections and the most prevalent bacteriumis Klebsiella pneumonia. All samples are sensitive to the nano silversolution with density of 100 ppm. Enterobacter aerogenes (24 mm) andPseudomonas aeruginosa (23mm) have the greatest Inhibitory zonediameter in the presence of 500 ppm of silver nanoparticles.Conclusion: It seems that silver nanoparticles have inhibitory effect on allstudied gram negative bacilli. The inhibitory effect of silver nanoparticlesagainst ESBL producing Gram negative bacteria is dose depended.Keywords: Gram-negative bacilli, ESBLs, silver nanoparticles