English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Two Escherichia coli isolates were recovered from the blood of two cancer patients and were demonstrated to produce high levels of the AmpC beta-lactamase with isoelectric points of &gt;9.0. The hypertranscription of ampC RNA was observed by Northern blot hybridization in both isolates. One isolate (isolate EC44) had a point mutation (G--&gt;A at position -28) and insertion of thymidine between positions -20 and -19 of the ampC promoter gene (GenBank accession no. AE000487). The single nucleotide insertion of T between positions -19 and -20 created an optimal distance (17 bp) in the Pribnow box for ampC hyperproduction. The other isolate (isolate EC38) had two point mutations (G--&gt;A at position -28 and C--&gt;T at position +58) and a 2-base (GT) insertion between positions -14 and -15. Although the insertion of GT between positions -14 and -15 may create a new promoter next to the original promoter, cloning of the ampC region with truncated nucleotides of the original -35 region of EC38 failed to verify the hypothesis that a new promoter would be created by such a nucleotide insertion. Instead, multiple start sites for ampC transcription at -1, +1, +2, and +3 were observed in an S1 nuclease protection assay. These results suggest that the RNA polymerase is flexible in the selection of a start site in ampC hypertranscription. In conclusion, nucleotide insertions between the -35 and -10 ampC promoter sequences was the mechanism for the hyperproduction of AmpC beta-lactamase and resistance to oxyimino-cephalosporins. The failure of the two patients to respond to treatment with oxyimino-cephalosporins highlights the important role of such a resistance mechanism in the clinical setting.

antimicrobial agents and chemotherapy

High-Level Expression of AmpC β-Lactamase Due to Insertion of Nucleotides between −10 and −35 Promoter Sequences in <i>Escherichia coli</i> Clinical Isolates: Cases Not Responsive to Extended-Spectrum-Cephalosporin Treatment

High-Level Expression of AmpC β-Lactamase Due to Insertion of Nucleotides between −10 and −35 Promoter Sequences in Escherichia coli Clinical Isolates: Cases Not Responsive to Extended-Spectrum-Cephalosporin Treatment