Translocation of antibiotic resistance determinants including an extended-spectrum ß-lactamase between conjugative plasmids of Klebsiella pneumoniae and Escherichia coli. Antimicrob. Agents Chemother

The extended-spectrum j-lactm CAZ-7, derivod from TEMs, was produced by two different strains of the family Enterobacteriaceae, KkbsiekUapeumoniae and Escherichia coil, isolated from the same patient. Both isolates were resistant to amdkacin. In addition, the K. pne no strain was TEM-1 producing and resistant to gentamicin. An E. colt HB101 transconjugant obtined from K.pneumo, selcted on ci de, showed that CAZ-7 and amikacin resistance were encoded by an 85-kb Inc7 or M plasid, while an E. coli HB101 transconjugant obtaind from E. coil under the same conditins showed that CAZ-7 and reisstnce were encoded by a>150-kb Inc6 or C plamid. Two other E. coUi HB101 tracugats I from K. pneumoniae, selected on gentamicin or chloramphenicol, showed that TEM-1 and gent n tnce could be encoded either by a>150-kb Inc6 or C p_asid or by an 85-kb Inc7 orM pl. It was hypotezed that the genes for P-lactam and aminoglycoside resistances were located on trnsloctable sequences. EcoRI digestion and hybridizations obtained with b1a., aacA4, and IS5I probes demonstrated that the CAZ-7 gene, amikacin resistance gene, and IS5I element were clustered on an-20-kb fament common to 85- and>150-kb plasmids. E. col HB101 transcomjugants from K. pneunoniae and E. coi isolates were used to obtain translocations of CAZ-7 and amikacin resisance and of TEM 1 and gen In between the 85->150-kb plasmids. This study shows a typical example of in vivo ge involving transposable elements which translocate multiresistance genes, including an extended-sp tru- e. Since 1984, members of the family Enterobacteriaceae that produce extended-spectrum,B-lactamases (ESbla) de-rived from TEM (CTX-1/TEM-3, CAZ-1/TEM-5, CAZ-2