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Molecular and biochemical characterization of a novel class A beta-lactamase (HER-1) from Escherichia hermannii.

ABSTRACT: Escherichia hermannii showed a low level of resistance to amoxicillin and ticarcillin, reversed by clavulanate, and a moderate susceptibility to piperacillin but was susceptible to all cephalosporins. A bla gene was cloned and encoded a typical class A beta-lactamase (HER-1, pI 7.5), which shares 45, 44, 41, and 40% amino acid identity with other beta-lactamases, AER-1 from Aeromonas hydrophila, MAL-1/Cko-1 from Citrobacter koseri, and TEM-1 and LEN-1, respectively. No ampR gene was detected. Only penicillins were efficiently hydrolyzed, and no hydrolysis was observed for cefuroxime and broad-spectrum cephalosporins. Sequencing of the bla gene in 12 other strains showed 98 to 100% identity with bla(HER-1).

SUBMITTER: Beauchef-Havard A

PROVIDER: S-EPMC166072 | biostudies-literature | 2003 Aug

REPOSITORIES: biostudies-literature

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Molecular and biochemical characterization of a novel class A beta-lactamase (HER-1) from Escherichia hermannii.

Beauchef-Havard Anne A Arlet Guillaume G Gautier Valerie V Labia Roger R Grimont Patrick P Philippon Alain A

Antimicrobial agents and chemotherapy 20030801 8

Escherichia hermannii showed a low level of resistance to amoxicillin and ticarcillin, reversed by clavulanate, and a moderate susceptibility to piperacillin but was susceptible to all cephalosporins. A bla gene was cloned and encoded a typical class A beta-lactamase (HER-1, pI 7.5), which shares 45, 44, 41, and 40% amino acid identity with other beta-lactamases, AER-1 from Aeromonas hydrophila, MAL-1/Cko-1 from Citrobacter koseri, and TEM-1 and LEN-1, respectively. No ampR gene was detected. On ...[more]

PMID: 12878539

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Project description:A clinical isolate, Escherichia coli MG-1, isolated from a 4-month-old Vietnamese orphan child, produced a beta-lactamase conferring resistance to extended-spectrum cephalosporins and aztreonam. In a disk diffusion test, a typical synergistic effect between ceftazidime or aztreonam and clavulanic acid was observed along with an unusual synergy between cefoxitin and cefuroxime. The gene for VEB-1 (Vietnamese extended-spectrum beta-lactamase) was cloned and expressed in E. coli JM109. The recombinant plasmid pRLT1 produced a beta-lactamase with a pI of 5.35 and conferred high-level resistance to extended-spectrum (or oxyimino) cephalosporins and to aztreonam. Vmax values for extended-spectrum cephalosporins were uncommonly high, while the affinity of the enzyme for ceftazidime and aztreonam was relatively low. blaVEB-1 showed significant homology at the DNA level with only blaPER-1 and blaPER-2. Analysis of the deduced protein sequence showed that VEB-1 is a class A penicillinase having very low levels of homology with any other known beta-lactamases. The highest percentage of amino acid identity was 38% with PER-1 or PER-2, two uncommon class A extended-spectrum enzymes. Exploration of the genetic environment of blaVEB-1 revealed the presence of gene cassette features, i.e., (i) a 59-base element associated with blaVEB-1; (ii) a second 59-base element just upstream of blaVEB-1, likely belonging to the aacA1-orfG gene cassette; (iii) two core sites (GTTRRRY) on both sides of blaVEB-1; and (iv) a second antibiotic resistance gene 3' of blaVEB-1, aadB. blaVEB-1 may therefore be the first class A extended-spectrum beta-lactamase that is part of a gene cassette, which itself is likely to be located on a class 1 integron, as sulfamide resistance may indicate. Furthermore, blaVEB-1 is encoded on a large (> 100-kb) transferable plasmid found in a Klebsiella pneumoniae MG-2 isolated at the same time from the same patient, indicating a horizontal gene transfer.

Dataset Information

Molecular and biochemical characterization of a novel class A beta-lactamase (HER-1) from Escherichia hermannii.

Publications

Molecular and biochemical characterization of a novel class A beta-lactamase (HER-1) from Escherichia hermannii.

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