Genetic linkage of the penicillinase gene, amp , and blrAB, encoding the regulator of beta-lactamase expression in Aeromonas spp

P Niumsup, AM Simm, K Nurmahomed, TR Walsh, PM Bennett, MB Avison

Research output: Contribution to journalArticle (Academic Journal)peer-review

29 Citations (Scopus)

Abstract

Aeromonas hydrophila T429125, a human clinical isolate, possesses three coordinately inducible beta-lactamases encoded by ampH (class D beta-lactamase), cepH (class C beta-lactamase) and imiH (class B beta-lactamase). We report that upstream of ampH there are two genes, blrA and blrB, encoding a putative two-component regulatory system. PCR studies revealed the same blrAB-amp gene arrangement in all Aeromonas spp. isolates tested; namely, Aeromonas veronii bv. sobria, Aeromonas jandaei, Aeromonas mediae, Aeromonas salmonicida and Aeromonas trota. A dominant mutation in the predicted BlrB kinase domain results in beta-lactamase overexpression in A. hydrophila T429125, but in other beta-lactamase-overexpressing mutants blrAB remains intact. Relative to the parent strain, A. hydrophila T429125, beta-lactamase- overexpressing mutants show a clear hierarchy of increased beta-lactamase expression: ImiH > CepH > AmpH. The same hierarchy is seen following beta-lactam challenge of A. hydrophila T429125, and correlates with the number of blr-tag sequences (TTCAC) found upstream of each beta-lactamase gene: ampH (one), cepH (two) and imiH (three).
Translated title of the contributionGenetic linkage of the penicillinase gene, amp , and blrAB, encoding the regulator of beta-lactamase expression in Aeromonas spp
Original languageEnglish
Pages (from-to)1351 - 1358
Number of pages8
JournalJournal of Antimicrobial Chemotherapy
Volume51
Publication statusPublished - Jun 2003

Bibliographical note

Publisher: Oxford University Press

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