en Anti-microbial agents, resistance and treatment protocols Anti-microbial agents, resistance and treatment protocols Original article Original article <strong>Introduction:</strong> The data on members of the genera <em>Proteus</em>, <em>Pseudomonas</em>, <em>Enterobacter</em>, <em>Citrobacter,</em> and <em>Staphylococcus</em> as the etiologic agents of urinary tract infections (UTIs) is not much.&nbsp; This study investigated the frequency of various beta-lactamases in urine isolates of <em>Proteus mirabilis</em>, <em>Enterobacter cloacae, </em>and <em>Citrobacter freundii</em> in Gorgan, Golestan province. <strong>Methods:</strong> A total of 632 urine samples were collected from hospitalized patients in a teaching hospital. The samples were cultured on blood agar and Eosin Methylene blue agar and incubated overnight at 37&deg;C. The cultures with a &ge;105 CFU/mL bacterial count were defined as positive for UTI. Bacteria identification was performed using standard biochemical methods and the API20E enteric identification system. The antibiotic resistance pattern was determined by the Kirby-Bauer disk diffusion method, and a phenotypic confirmatory test was used for detecting ESBL, MBL, and AmpC beta-lactamases producers. <strong>Results: </strong>Out of 632 samples, 317 (50.1%) were positive for UTIs, and 27 (8.5%), 21 (6.6%), and 12 (3.7%) were positive for<em> Enterobacter cloacae</em>, <em>Citrobacter freundii,</em> and <em>Proteus mirabilis</em> isolates, respectively. All the isolates were sensitive to piperacillin-tazobactam and colistin. The prevalence of ESBL and AmpC beta-lactamases in <em>P. mirabilis</em> isolates was higher than the other isolates, but No MBL producers were detected. <strong>Conclusions:</strong> In this study, the high frequency of ESBL and AmpC beta-lactamases in <em>P. mirabilis</em> isolates may suggest an increasing trend in resistance to cephalosporins and monobactams, which could have a significant impact on the management and treatment of UTI caused by this organism. Therefore, continuous monitoring is required to control the spread of &beta;-lactamase-producing isolates in different geographical areas.<br> &nbsp; Beta-lactamases, Proteus mirabilis, Enterobacter cloacae, Citrobacter freundii, Prevalence 161 165 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-310-2&slc_lang=en&sid=1 Ameneh Fenderski ftm.fendereski@gmail.com 0000-0002-2178-8365 No Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran Ania Ahani Azari ania_783@yahoo.com 0000-0001-7025-6739 Yes Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran Teena Dadgar dadgar_teena@yahoo.com 0000-0002-0839-0838 No Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran