Tehran University Medical Journal

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Background: Antimicrobial resistance is a growing problem in many bacterial pathogens and is of particular concern for hospital-acquired nosocomial infections. Klebsiella pneumonia is an important cause of nosocomial infections has rapidly become the most common extended spectrum beta-lactamases (ESBLs) producing organism. ESBL are defined as the enzymes capable of hydrolyzing oxyimino-cephalosporins. The aim of this study was to compare phenotypic detection of ESBL using two phenotypically method among the clinical isolates of Klebsiella pneumoniae. Methods: In this cross-sectional study a total of 144 isolates from clinical samples Urine, sputum, wound, blood, throat and body fluids isolated and identified as K. pneumoniae in a teaching hospitals in Shiraz within a six months period from December 2012 to May 2013. Antibacterial susceptibility test performed to 14 antibiotics by the disk diffusion method according to CLSI guideline and then isolates that were resistant to at least one of the beta-lactam antibiotics evaluated for the production of beta-lactamase enzymes by using E-test ESBL and combined disk method. Results: Totally 38 (26.3%) isolates produced ESBLs. All ESBL producing isolates were susceptible to imipenem and meropenem and resistant to aztreonam. The highest antibiotic resistance was observed for amoxicilin (100%) and the lowest antibiotic resistance was observed for meropenem (9.7%). The number of 38 (100%) isolates were identified as ESBL producer by using E-test ESBL ceftazidime. It was while using the combined disks ceftazidime/clavulanic acid, cefotaxime/clavulanic acid and cefpodoxime/clavulanic acid, respectively 35 (92.1%), 34 (89.4%) and 31 (81.5%) of isolates identified as beta-lactamase producing isolates. Conclusion: Considering the high prevalence of bacteria producing ESBL, screening for infections caused by ESBL-producing isolates may be lead to the most effective antibiotics therapies.