Minimum Inhibitory Concentrations (MICs) of ciprofloxacin were determined by the microdilution method according to Clinical and Laboratory Standards Institute (CLSI) guidelines [12 ]. The susceptibility to other antimicrobial agents was determined using Kirby-Bauer disk diffusion test with antimicrobial agent discs (OXOID, UK) following the CLSI guidelines [13 (link)]. E. coli ATCC 25922 and K. pneumoniae ATCC 10031 were used as means of quality control.
Isolates with reduced susceptibility to third generation cephalosporins were subjected to phenotypic detection of ESBL production by using cefotaxime (CTX) and ceftazidime (CAZ) discs and double-disk synergy (DDS) method as recommended by the Clinical and Laboratory Standards Institute [14 ]. AmpC production was detected using cefoxitin alone and in combination with boronic acid and confirmation was done by three-dimensional disk method. Isolates with reduced susceptibility to cefoxitin were subjected to a modified three-dimensional extract test to confirm AmpC production [15 ].
Isolates with reduced susceptibility to third generation cephalosporins were subjected to phenotypic detection of ESBL production by using cefotaxime (CTX) and ceftazidime (CAZ) discs and double-disk synergy (DDS) method as recommended by the Clinical and Laboratory Standards Institute [14 ]. AmpC production was detected using cefoxitin alone and in combination with boronic acid and confirmation was done by three-dimensional disk method. Isolates with reduced susceptibility to cefoxitin were subjected to a modified three-dimensional extract test to confirm AmpC production [15 ].