en 34012526 <p style="text-align:justify"><span style="font-size:11pt"><span style="font-size:9.5pt">Background:</span><span style="font-size:10.0pt"> <em>Pseudomonas aeruginosa (P. aeruginosa)</em> is an opportunistic pathogen causing a wide range of human infections. The organism is resistant to a wide range of antibiotics. The purpose of this study was to investigate the effect of AgNPs on pyocyanin pigment production of <em>P. aeruginosa</em> bacteria isolated from clinical specimens.</span></span></p> <p style="text-align:justify"><span style="font-size:11pt"><span style="font-size:9.5pt">Methods:</span><span style="font-size:10.0pt"> In this study, 15 clinical isolates of <em>P. aeruginosa</em> were collected from different specimens of hospitalized patients. <em>P. aeruginosa</em> was detected by biochemical and molecular (detection of pbo1 gene by colony PCR method) methods and the MIC and MBC of AgNPs were determined by agar dilution method. Inhibition of <em>P. aeruginosa</em> pyocyanin production at AgNPs concentrations of 0, 0.3, 0.5, 1 and 1.5 <em>mg/ml</em> of was studied with OD of 520 <em>nm</em>.</span></span></p> <p style="text-align:justify"><span style="font-size:11pt"><span style="font-size:9.5pt">Results:</span><span style="font-size:10.0pt"> The mean MIC and MBC of AgNPs were 1.229 and 1.687 <em>mg/ml</em>, respectively. Pyocyanin production was investigated for all isolates at different concentrations of nanoparticles, and their comparison showed that with increasing nanoparticle concentration, pyocyanin production significantly decreased (p&lt;0.05).</span></span></p> <p style="text-align:justify"><span style="font-size:9.5pt">Conclusion:</span> <span style="font-size:10.0pt">According to the results of this study, AgNPs had an inhibitory effect on <em>P. aeruginosa</em> and its pigment production and with increasing nanoparticles concentration, pigment production decreased; therefore, it seems that the nanoparticles can be used to treat and prevent diseases caused by <em>P. aeruginosa</em>.</span></p> Nanoparticles, Polymerase chain reaction , Pseudomonas aeruginosa, Pyocyanin 98 103 https://www.ajmb.org/En/Article.aspx?id=40457 https://www.ajmb.org/PDF/En/FullText/40457.pdf MahboobehNajafiDepartment of Biology, Faculty of Science, Damghan Branch, Islamic Azad University, Damghan, Iran61735MahboobehNakhaei MoghaddamDepartment of Biology, Faculty of Science, Mashhad Branch, Islamic Azad University, Mashhad, Iran61736EhsanYousefi61737