Meropenem resistant Klebsiella pneumoniae and Escherichia coli isolates were analyzed. A total of 18 non-duplicate meropenem resistant K. pneumoniae and one E. coli isolates from hospitalized patients were analyzed by polymerase chain reaction (PCR) and DNA sequencing to detect the OXA-48, IMP, VIM, and SPM-1 genes. Susceptibilities to antimicrobials were determined using an agar dilution method and E-test; beta-lactamase production was detected by double disk synergy test [Imipenem, imipenem/ethylenediaminetetraacetic acid (EDTA)] (DDST), E-test MBL and E-test ESBL. Homology of the isolates was determined by randomly amplified polymorphic DNA typing (RAPD). Minimum inhibitory concentrations (MICs) of imipenem and meropenem were 2 to 8 and 4 to > 512 mg/L for K. pneumoniae; 2 and 32 mg/L for E. coli, respectively. The isolates were resistant to all beta-lactams. The DDST was positive only for the E. coli. PCR and sequencing identified bla(IMP-1) in the E. coli strain and bla(OXA-48) in all K. pneumoniae isolates. RAPD-PCR indicated that spread of OXA-48 producing K. pneumoniae in the pediatric intensive care unit (ICU) from June, 2007 to December, 2007 was clonal. This is the first report of IMP-1-producing E. coli in Turkey, while OXA-48 carbapenemases in K. pneumoniae have been reported recently from our country. Carbapenem resistance may spread among Enterobacteriaceae via the transferable enzyme OXA-48, as well as metallo-beta-lactamases.