Six high-level aminoglycoside and third generated cephalosporin of cefotaxime resistance Klebsiella pneumoniae, Klebsiella oxytoca, and Escherichia coli isolated from clinical specimens in the same Japanese hospital since 2001. These 6 strains were resistant to all 4,6-disubstituted deoxystreptamine including albekacin. The results of multiplex PCR for 16S rRNA methylase and bla_, bla_, bla_ specific PCR reaction show that these strains harbor 16S rRNA methylase of rmtB and β-lactamase resistance gene of bla_ group in the same large plasmid. Sequence analysis of bla_ group PCR products shows this β-lactamase is bla_. rmtB-harbored plasmids are classified the IncA/C by PCR and restriction pattern by EcoRI show only one or two band differences. Moreover, southern hybridization of EcoRI digested rmtB harbored plasmid by rmtB probe show the same hybridization pattern of 4.8 kbp bands. PFGE fingerprinting analysis of four K. pneumoniae revealed two fingerprinting patterns. These facts suggested that rmtB-positive starains not only spread horizontal transfer of rmtB-harbored plasmid but also clonal spread of the same strain
