en میکروب شناسی Microbiology مقالات اصلی Original Article <div style="text-align: justify;"><strong><em>Background:</em></strong> Klebsiella pneumoniae (K. pneumoniae) is an opportunistic microorganism and one of the&nbsp;most important causes of urinary tract infection. This study aimed to evaluate the frequency of K.&nbsp;pneumoniae producing broad-spectrum beta-lactamase in urinary tract infection and to determine the pattern&nbsp;of drug resistance.<br> <br> <strong><em>Methods:</em></strong> This study was performed on 50 samples of K. pneumoniae isolated from patients with&nbsp;urinary tract infection referred to the Medical Diagnostic Laboratory in Hashtgerd city. The isolates&nbsp;were first evaluated for antibiotic susceptibility by disk diffusion method according to the method&nbsp;proposed by the Clinical and Laboratory Standards Institute (CLSI). Then phenotypic detection of&nbsp;ESBLS was carried out by the DDST method. The frequency of gene blaTEM and blaCTX-M was&nbsp;determined by PCR.<br> <br> <strong><em>Results:</em></strong> The highest resistance was observed to ampicillin (94%) and the highest sensitivity was observed&nbsp;to gentamicin (84%). 22 isolates (44%) were positive for ESBLs production. Of the 50 isolates studied,&nbsp;34% had blaCTX-M and 28% had blaTEM and 11 (22%) had both genes simultaneously. Also, more than&nbsp;77% of positive ESBLs isolates had the blaCTX-M gene and approximately 63.64% of positive ESBLs&nbsp;isolates had the blaTEM gene.<br> <br> <strong><em>Conclusions: </em></strong>Given the high prevalence of antibiotic-resistant and ESBL-producing isolates, early&nbsp;identification of these resistant isolates and their follow-up is essential to prevent further outbreaks.&nbsp;It is also important to use appropriate therapeutic strategies and proper and rational administration of<br> antibiotics by physicians.</div> Antibiotic Resistance, ESBLs, K. pneumoniae, Urinary Tract Infection. 412 419 http://rbmb.net/browse.php?a_code=A-10-689-1&slc_lang=en&sid=1 Shirin Sarshar 100319475328460012539 100319475328460012539 No Master of Sciences (M.Sc.) Microbiology, Department of Microbiology, Faculty of Sciences, Karaj Branch, Islamic Azad University, Karaj, Iran. Reza Mirnejad 100319475328460012540 100319475328460012540 No Professor of Medical Bacteriology, Molecular Biology Research Center, Systems biology and poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran. Ebrahim Babapour e.babapour@kiau.ac.ir. 100319475328460012541 100319475328460012541 Yes Assistant Professor of Microbiology, Department of Microbiology, Karaj Branch, Islamic Azad University, Karaj, Iran.