phenotypic identification and antibiotic susceptibility pattern of ampc beta-lactamase producing escherichia coli and klebsiella pneumoniae isolated from urinary tract infections from a tertiary care hospital of rawalpindi, pakistan

introduction: this study is aimed to compare phenotypic test methods and determine antibiotic susceptibility pattern of ampc beta-lactamase producing uropathogenic escherichia coli and klebsiella pneumoniae in clinical isolates. method: e. coli and k. pneumoniae were identified by standard microbiological procedures. screening of ampc beta-lactamase production was done by using cefoxitin disc (30 µg) 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. results: 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, e. coli were n=57 (69.51%) and k. pneumoniae 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. conclusion: 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.