en Anti-microbial agents, resistance and treatment protocols Anti-microbial agents, resistance and treatment protocols Original article Original article <strong>Introduction</strong>: Extended-Spectrum &beta;-Lactamases (ESBLs) hydrolyze broad-spectrum cephalosporin, monobactam, and penicillin. This study investigated ESBL-producing <em>Escherichia coli</em> and <em>Klebsiella pneumoniae </em>bacteria in the Gaza strip and explored their susceptibility to various antimicrobials to provide a reference for physicians in managing the hospital infection.<strong> Methods: </strong>Ninety-six isolates, comprising 69 <em>E. coli </em>and 27<em> K. pneumoniae</em> were obtained from urine, wound, blood, and ear discharge samples from April-June 2013 in Gaza hospitals. The ESBL-producing isolates were screened using the double-disc diffusion test. Antibiotics susceptibility test was determined by the disc diffusion method on Mueller-Hinton agar, and PCR identified &beta;-lactamases genes.<strong> Results:</strong> Our results revealed high rates of ESBL-producing <em>K. pneumoniae </em>(59.3%) and <em>E. coli </em>(39.1%) among isolates. About 65.1% of ESBL-producing isolates were susceptible to imipenem while exhibited 100% resistance to cefotaxime and ampicillin and 74.4% to sulfamethoxazole/trimethoprim.&nbsp;Except for imipenem, higher antibiotic resistance rates were observed among ESBL producers than non-ESBL producers. This study showed that the antimicrobial resistance and ESBLs were higher in <em>K. pneumoniae </em>isolates than <em>E. coli</em> isolates<em>,</em> and most <em>K. pneumoniae </em>isolates harbored simultaneously two or three &beta;-lactamases-encoding genes.<strong> Conclusion: </strong>High ESBL-producing rates among <em>K. pneumoniae</em> and <em>E. coli </em>isolates and higher resistance rates to antibiotics among ESBL compared to non-ESBL producing isolates necessitate antimicrobial resistance surveillance and molecular characterization of ESBLs-producing bacteria to achieve a specific treatment. Beta-lactamase genes, ESBL isolates, Antibiotics resistance, Carbapenem, E. coli, K. pneumonia 133 141 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-342-1&slc_lang=en&sid=1 Ghassan Tayh ghassan.tayh@fst.utm.tn 0000-0002-7180-6787 Yes Laboratoire des Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Université de Tunis El Manar, 2092 Tunis, Tunisie Nahed Al Laham n.lahamm@alazhar.edu.ps 0000-0002-7019-7975 No Department of Laboratory Medicine, Faculty of Applied Medical Sciences, AlAzhar University-Gaza, Palestine Imene Fhoula fhoulaimene@gmail.com 0000-0001-6416-685X No Laboratoire des Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Université de Tunis El Manar, 2092 Tunis, Tunisie Nahed Abedelateef nalateef@gmail.com 0000-0003-4158-982X No Biological Science, Al-Aqsa University –Gaza, P. O. Box 4051, Gaza strip, Palestine. Mohamed El-Laham ml19822@gmail.com 0000-0003-1494-7943 No Biological Science, Medical Technology, Israa University – Gaza, Gaza strip, Palestine. Abed Elkader Elottol aelottol@gmail.com 0000-0001-5281-6405 No Medical Science Department, University College of Science and Technology - Gaza, Khan Yunis, Gaza Strip, Palestine.. Karim Ben Slama karim.benslama@issbat.utm.tn 0000-0001-5745-3930 No Laboratoire des Microorganismes et Biomolécules Actives, Faculté des Sciences de Tunis, Université Tunis-El Manar, 2092 Tunis & Tunisie. Institut Supérieur des Sciences Biologiques Appliquées de Tunis.