en Anti-microbial agents, resistance and treatment protocols Anti-microbial agents, resistance and treatment protocols Original article Original article <p dir="ltr"><strong>Introduction:</strong> <em>Stenotrophomonas maltophilia</em> is a nosocomial multi drug resistant opportunistic pathogen which causes infections in vulnerable patients with cancer, cystic fibrosis and indwelling catheters. <strong>Methods:</strong> 45 clinical <em>S. maltophilia</em> isolates were collected from blood samples and identified by biochemical tests. Susceptibility to different antibiotics including co-trimoxazole, levofloxacin, minocycline, ticarcillin/clavulanic acid, chloramphenicol and ceftazidime were determined by disk diffusion and E-test methods. <strong>Results</strong>: All isolates were resistant to ceftazidime and susceptible to co-trimoxazole and&nbsp; 11.1% were resistant to ticarcillin/clavulanic acid. <strong>Conclusion:</strong> Ceftazidime as one of the extended spectrum &beta;-lactams was the least effective antibiotic. Ticarcillin/clavulanic acid is one of the choosen antibiotics for <em>S. maltophilia</em> infections treatment. Here, we report tcarcillin/clavulanic acid resistance in <em>S. maltophilia</em> isolates for the first time in Iran.</p> Stenotrophomonas maltophilia, Antimicrobial susceptibility, Iran 35 37 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-106-1&slc_lang=en&sid=1 Amir Hesam Nemati Hesam.nemati@live.com No Bacteriology department, pasteur Institute of Iran, Tehran, Iran Hamid Solgi No Bacteriology department, pasteur Institute of Iran, Tehran, Iran Farzam Vaziri farzam_vaziri@yahoo.com No Tuberculosis and pulmonary research department, Pasteur institute of Iran, Tehran, Iran Fereshteh Shahcheraghi shahcheraghifereshteh@yahoo.com Yes Bacteriology department, pasteur Institute of Iran, Tehran, Iran