Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 14 6 2022 12 06 802 812 Raheleh Karimiravesh Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Ashraf Mohabati Mobarez Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Mehrdad Behmanesh Department of Genetics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran Maryam Nikkhah Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran Amin Talebi Bezmin Abadi Department of Bacteriology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Saber Esmaeilli National Reference Laboratory for Plague, Tularemia and Q fever, Research Centre for Emerging and Reemerging Infectious Diseases, Pasteur Institute of Iran, Akanlu, Kabudar Ahang, Hamadan, Iran AND Department of Epidemiology and Biostatistics, Research Centre for Emerging and Reemerging Infectious Diseases, Pasteur Institute of Iran, Tehran, Iran 2022 09 12 2022 11 17 Background and Objectives: Legionella spp. is a causative agent of Legionnaires' disease that creates public health problems. Isolation of these bacteria from water sources is essential to identify outbreak origins and prevent disease. Diagnostic biosensors for water quality control to protect consumers from water-borne infections can predict many outbreaks. Gold nanoparticles conjugated probes are a new generation of diagnostic tools. In this study, an optical nano biosensor was designed and characterized to detect Legionella pneumophila in water samples rapidly. Materials and Methods: Thiolated probes designed for the mip gene were attached to gold nanoparticles and then water samples containing Legionella pneumophila were examined. Results: The limit of detection for PCR and biosensor was 104 and 103 copy numbers/µl, respectively. Biosensor sensitivity and PCR were reported to be 90% (18 out of 20) and 85% (17 out of 20), respectively. Specificity 100% has been reported for both methods. Conclusion: According to the obtained results, this method has the potential to diagnose L. pneumophila with high sensitivity and specificity. This system can be employed as a practical tool for rapid, accurate, high-sensitivity, and acceptable detection of Legionella pneumophila in contaminated water, which is cost-effective in terms of cost and time. https://ijm.tums.ac.ir/index.php/ijm/article/view/3903 https://ijm.tums.ac.ir/index.php/ijm/article/download/3903/1520