Transposition of the gene encoding a TEM-12 extended-spectrum beta-lactamase

Abstract

An isolate of Klebsiella oxytoca from the blood culture of a child with leukemia was found to produce two beta-lactamases, at least one of which conferred resistance to ceftazidime. Genes encoding both enzymes were located on a single self-transmissible 100-kb plasmid, pOZ201. This plasmid was introduced into Escherichia coli UB5201 (pACYC184), and the gene encoding one beta-lactamase was transposed onto plasmid pACYC184 by exploiting a gene dosage effect. The transposable gene was found to encode a TEM-12 enzyme as determined by nucleotide sequencing. This gene was subsequently transposed onto plasmid pUB307. The transposable element encoding the TEM-12 enzyme has been designated Tn841. Both plasmids pACYC184::Tn841 and pUB307::Tn841 were shown to encode a beta-lactamase with the same isoelectric point and substrate profile as the TEM-12 beta-lactamase. Transposon Tn841, at approximately 7 kb, is larger than TnA (4.8 kb) and transposes at a lower frequency. Although it produced a resolvase which can complement the resolvase of Tn3, its transposase function was not able to complement the transposition of a TnA element which lacked transposase. The occurrence of a gene encoding an extended-spectrum beta-lactamase on a transposable element in a clinically significant bacterium is potentially a cause for concern for the spread of resistance to the extended-spectrum cephalosporins.

Multiply resistant Klebsiella pneumoniae strains from two Chicago hospitals: identification of the extended-spectrum TEM-12 and TEM-10 ceftazidime-hydrolyzing beta-lactamases in a single isolate

“…Recently, TEM-12 and TEM-10 (TEM-23) ,B-lactamases were identified in sequential isolates of E. coli from a single patient; however, the two ,-lactamases were produced only one at a time (33). In another report, TEM-12 was identified in an isolate of K oxytoca which also produced an uncharacterized 3-lactamase with a pI of 5.6 (11). The TEM-12-encoding gene from' this isolate was demonstrated to be harbored on a transposon by means of transposition experiments.…”

Carbapenem-Resistant Strain of Klebsiellaoxytoca Harboring Carbapenem-Hydrolyzingβ-LactamaseKPC-2

“…Since pBR322-catI is a multicopy cloning vector, we hypothesized that it would facilitate the detection of the transposition of bla KPC-2 from the 70-kb plasmid by a gene dosage assay (21). The frequency of bla KPC-2 transposition was 9.7 ϫ 10 Ϫ4 , as indicated by the number of colonies with elevated imipenem MICs (i.e., those growing on 128-g/ml versus 16-g/ml imipenem).…”

“…The gene dosage assays were performed as described by Heritage et al (21). The plasmid pBR322-catI (47) was used for this assay.…”

Insertion Sequence IS Ecp1B Is Involved in Expression and Mobilization of a bla CTX-M β-Lactamase Gene

“…Since several ESBL genes may be transposon or integron borne (23,37,38,40,41), the surrounding sequences of the bla CTX-M-19 gene were explored further to identify a class 1 integron that may contain this gene (22). This has been done using PCR amplification experiments and the natural plasmid pILT-3 carrying the bla CTX-M-19 gene as the template (39).…”