Plasmid-mediated quinolone resistance mechanisms in extended spectrum beta-lactamase positive and quinolone resistant Escherichia coli and Klebsiella pneumoniae strains isolated from Ege University Hospital were investigated. The presence of qnrA, qnrB, qnrS, aac(6')-lb and qepA genes were detected by PCR and the products were sequenced. Clonal relationship of isolates was determined by REP-PCR and mutations in gyrA and parC genes were investigated in representative strains. aac(6')-lb-cr, qnrB and qnrS genes were detected in both E. coli and K. pneumoniae strains, but qnrA detected only in K. pneumoniae strains. qepA determinant is detected in an E. coli strain first time in Turkey. Mutations were observed in both gyrA and parC genes of all representative nalidixic acid and ciprofloxacin resistant E. coli isolates but no mutation was found in parC genes of E. coli and K. pneumoniae strains that were resistant to only nalidixic acid.