CMY-16, a novel acquired AmpC-type β-lactamase of the CMY/LAT lineage in multifocal monophyletic isolates of Proteus mirabilis from northern Italy

Marco M. D'Andrea, Elisabetta Nucleo, Francesco Luzzaro, Tommaso Giani, Roberta Migliavacca, Francesca Vailati, Vesselina Kroumova, Laura Pagani, Gian Maria Rossolini

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Abstract

We report multifocal detection (four different cities in northern Italy) of Proteus mirabilis isolates resistant to both oxyimino- and 7-α-methoxy- cephalosporins and producing a novel acquired AmpC-like β-lactamase. The enzyme, named CMY-16, is a variant of the CMY/LAT lineage, which differs from the closest homologues, CMY-4 and CMY-12, by a single amino acid substitution (A171S or N363S, respectively) and from CMY-2 by two substitutions (A171S and W221R). Expression of the cloned blaCMY-16 gene in Escherichia coli decreased susceptibility to penicillins, cephalosporins, and aztreonam. Tazobactam was more effective than clavulanate at antagonizing the enzyme activity. Genotyping, by random amplification of polymorphic DNA and pulsed-field gel electrophoresis of genomic DNA digested with SfiI, showed that isolates were clonally related to each other, although not identical. The blaCMV-16 gene was not transferable to E. coli by conjugation or transformation. In all isolates, it was chromosomally located and inserted in a conserved genetic environment. PCR mapping experiments revealed that the blaCMY-16 was flanked by ISEcp1 and the blc gene, similar to other genes of this lineage from plasmids of Salmonella enterica, Klebsiella spp., and E. coli. Overall, these results revealed multifocal spreading of a CMY-16-producing P. mirabilis clone in northern Italy. This finding represents the first report of an acquired AmpC-like β-lactamase in Proteus mirabilis from Italy and underscores the emergence of similar resistance determinants in the European setting.

Original languageEnglish
Pages (from-to)618-624
Number of pages7
JournalAntimicrobial Agents and Chemotherapy
Volume50
Issue number2
DOIs
Publication statusPublished - Feb 2006

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ASJC Scopus subject areas

  • Pharmacology (medical)

Cite this

D'Andrea, M. M., Nucleo, E., Luzzaro, F., Giani, T., Migliavacca, R., Vailati, F., Kroumova, V., Pagani, L., & Rossolini, G. M. (2006). CMY-16, a novel acquired AmpC-type β-lactamase of the CMY/LAT lineage in multifocal monophyletic isolates of Proteus mirabilis from northern Italy. Antimicrobial Agents and Chemotherapy, 50(2), 618-624. https://doi.org/10.1128/AAC.50.2.618-624.2006