Hamadan University of Medical Sciences Avicenna Journal of Clinical Microbiology and Infection 2383-0298 6 1 2019 02 01 The Prevalence of Virulence Factors in Human and Environmental Isolates of Pseudomonas aeruginosa 9 14 10.34172/ajcmi.2019.03 EN Sayyad Gholami https://orcid.org/0000-0003-1703-7056 Mohammad Tabatabaei https://orcid.org/0000-0002-3743-6583 Journal Article 10.34172/ajcmi.2019.03 2019 01 02 2019 02 06 Background: Pseudomonas aeruginosa as a gram-negative bacterium can be detected all around us, as it is generally distributed in different environments and can act as a probable cause of human diseases especially in immunocompromised patients. This bacterium also is a leading cause of nosocomial infections in burn intensive care units. The aim of this study was to evaluate the presence of some virulence genes in P. aeruginosa isolated from different sources. Methods: Pseudomonas aeruginosa isolates were evaluated for the presence of virulence factors including toxA, phzM, lasB, exoU, exoS genes by polymerase chain reaction (PCR). Results: According to our findings, the prevalence of toxA, phzM, lasB, exoU, and exoS virulence genes in the isolates originated from human sources was 86%, 16%, 94%, 100%, and 78%, respectively. While, the above-mentioned virulence factors were present in 46%, 4%, 68%, 64%, and 62% of environmental samples, respectively. Conclusions: Findings of this study indicated that the presence of virulence genes in human isolates was greater than their presence in environmental isolates. Hence, it seems this difference may have caused infections in humans.