en Original article Original article <p> <strong><i> Pseudomonas aeruginosa </i></strong><strong>is among the most important pathogens in the nosocomial infections. A genetic mobile element, the integron, is one of the major agents involved in dissemination of multi-drug resistance among gram negative bacteria. During a descriptive study from October 2009 to August 2010, some 130 <i>P. aeruginosa</i> clinical isolates were collected from different wards of three hospitals in Tehran. The Minimal inhibitory concentration (MIC) of 4 antibiotics conventionally used in clinical settings against the isolates was determined by E-test method. Also, the existence of integron classes and metallo-β-lactamases (<i>bla</i>_VIM-1,<i> bla</i>_IMP-1, and <i>bl</i>a_VIM-2) were investigated by PCR assay. Out of 130 isolates, 74 (56.9%) carried class 1 integron. None of the isolates harbored integrons class 2 and 3. Also, the <i>bla</i>_VIM-1gene was detected in 10 (13.3%) high level ceftazidime and imipenem- resistant isolates that carried class 1 integrons. The <i>bla</i>_IMP-1and<i> bl</i>a_VIM-2 genes were not detected in any isolates. In the present study, the antibiotic resistance rates in class 1 integron-positive isolates of <i>P. aeruginosa</i> were significantly higher than those lacking this integron , e.g., 82.6% resistance versus 17.3% sensitivity to ceftazidime. Also, 13.3% of ceftazidime and imipenem resistant isolates was metallo-β-lactamase producer. This indicates that all metallo-β-lactamase genes are correlated with class 1 integrons. These results imply that the <i>bla</i>_VIM-1 gene has been presumably dispersed into <i>P. aeruginosa</i> isolates with the help of class 1 integron element. </strong></p> β-lactam, Integron, Antibiotic resistance, Metallo-β-lactamase, Pseudomonas aeruginosa 46 51 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-25-13&slc_lang=en&sid=1 Somayeh Azami No Department of Microbiology, Faculty of Sciences, Alzahra University, Tehran, Iran Ahya Abdi Ali Yes Department of Microbiology, Faculty of Sciences, Alzahra University, Tehran, Iran Ezzat Asgarani No Department of Microbiology, Faculty of Sciences, Alzahra University, Tehran, Iran