antimicrobial susceptibility testing (AST) using disk diffusion technique
according to the Clinical and Laboratory Standards Institute (CLSI)
instructions
gentamicin (CN, 10 μg), ciprofloxacin (CIP, 5 μg), ceftazidime (CAZ, 30 μg),
levofloxacin (LEV, 5 μg), amoxicillin/clavulanate (AMC, 30 μg), trimethoprim
(TMP, 5 μg), norfloxacin (NOR, 10 μg), cefotaxime (CTX, 30 μg), nitrofurantoin
(F, 300 μg), imipenem (IPM, 10 μg), chloramphenicol (C, 30 μg), tetracycline
(TE, 30 μg), and ceftriaxone (CRO, 30 μg) (Bioanalyse, Turkey). MDR isolates
were determined according to the previous definition (resistance to at least one
member of three antibiotics classes)
pneumoniae ATCC 700603 were used as quality control strains.