Characterisation of KLUA-9, a β-lactamase from extended-spectrum cephalosporin-susceptible Kluyvera ascorbata , and genetic organisation of blaKLUA-9

Abstract This study characterised the genetic environment of the chromosomally encoded blaKLUA-9 gene from a clinical Kluyvera ascorbata isolate and performed a kinetic characterisation of KLUA-9. Purified KLUA-9 showed the highest catalytic efficacies towards benzylpenicillin, ampicillin, piperacil...

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Published in:International journal of antimicrobial agents 2007-03, Vol.29 (3), p.332-337
Main Authors: Rodríguez, María Margarita, Power, Pablo, Bauvois, Cédric, Di Conza, José, Ayala, Juan A, Galleni, Moreno, Gutkind, Gabriel
Format: Article
Language:English
Subjects:
Antibiotics. Antiinfectious agents. Antiparasitic agents
Biological and medical sciences
Escherichia coli
Infectious Disease
Kluyvera
Medical sciences
Pharmacology. Drug treatments
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Summary:Abstract This study characterised the genetic environment of the chromosomally encoded blaKLUA-9 gene from a clinical Kluyvera ascorbata isolate and performed a kinetic characterisation of KLUA-9. Purified KLUA-9 showed the highest catalytic efficacies towards benzylpenicillin, ampicillin, piperacillin, first-generation cephalosporins, cefuroxime and cefoperazone; like other ‘cefotaximases’, it showed a much higher rate of hydrolysis of cefotaxime than ceftazidime, whilst dicloxacillin, cefoxitin and imipenem behaved as poor substrates. A 9 kb insert from K. ascorbata was cloned ( Escherichia coli KK68C1) and sequenced. blaKLUA-9 and its 266 bp upstream flanking region (almost identical to the integron-associated blaCTX-M-2 ) are preceded by an aspat variant, a ypdABC -like operon and two open reading frames with unknown functions. Unlike IS CR1 -associated blaCTX-M-2 genes, we failed to detect the putative orf513 recombination sites. Instead, we were able to localise the 5 bp target sites for insertion of IS Ecp1B , suggesting that this element could be responsible for future (or still undetected) mobilisation of blaKLUA-9 to more efficiently transferred elements.
ISSN:0924-8579
1872-7913
DOI:10.1016/j.ijantimicag.2006.09.015