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> This study is aimed to compare phenotypic test methods and determine antibiotic susceptibility pattern of AmpC beta-lactamase producing uropathogenic <em>Escherichia coli </em>and <em>Klebsiella pneumoniae</em> in clinical isolates. <strong>Method: </strong><em>E. coli </em>and <em>K. pneumoniae </em>were identified by standard microbiological procedures. Screening of AmpC beta-lactamase production was done by using cefoxitin disc (30 &micro;g) showing inhibition zone diameter of <18 mm. Then, screen-positive isolates were subjected to Disc Approximation Test (DAT) and three dimensional extract test (3-DET) methods. Antibiotic susceptibility testing was performed by Kirby Bauer Disc diffusion technique. <strong>Results:</strong> A total of 120 Gram Negative Rods (GNRs) were included in the study. Amongst them cefoxitin resistant isolates were 68.33% (n=82/120). In these 82 isolates, <em>E. coli</em> were n=57 (69.51%) and <em>K. pneumoniae</em> were n=25 (30.48%). DAT identified 52.43% of AmpC beta-lactamase producing isolates, sensitivity of DAT was found to be 88% with 92% specificity, Positive Predictive Value of 92.68%, Negative Predictive Value of 87.80%, and Diagnostic Accuracy of 90.24%. Antibiotic susceptibility testing by Kirby Bauer Disc diffusion technique showed that carbapenems (meropenem) and tigecycline were of higher therapeutic effects against these resistant pathogens. <strong>Conclusion: </strong>Introducing simple tests like DAT in the laboratories can control the spread of AmpC beta-lactamase harboring organisms. Carbapenems (meropenem) and tigecycline are of suitable therapeutic effect against these resistant pathogens.</p> Extended spectrum beta-lactamase, Disc approximation test, Three dimensional extract test 143 146 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-67-1&slc_lang=en&sid=1 Nadia Saad docnadiasaad@gmail.com Yes National University of Science and Technology, Islamabad Tehmina Munir tehmunir_doc@yahoo.com No National University of Science and Technology, Islamabad Maliha Ansari maliha.atif1@gmail.com No National University of Science and Technology, Islamabad Mehreen Gilani mehreen.umar@hotmail.com No National University of Science and Technology, Islamabad Mahwish Latif latif_mahwish@hotmail.com No National University of Science and Technology, Islamabad Amira Haroon amiraharoon12@gmail.com No National University of Science and Technology, Islamabad