[Source: Antimicrobial Agents and Chemotherapy, full text: (LINK). Abstract, edited.]
FIM-1, a new acquired metallo-β-lactamase from a Pseudomonas aeruginosa clinical isolate from Italy

Simona Pollini a, Simona Maradei a, Patrizia Pecile b, Giuseppe Olivo c, Francesco Luzzaro d, Jean-Denis Docquier a and Gian Maria Rossolini a,e,#

Author Affiliations: <SUP>a</SUP>Department of Biotechnologies, Section of Microbiology, University of Siena; <SUP>b</SUP>Microbiology and Virology Unit; <SUP>c</SUP>Cardiac Intensive Care Unit, Careggi University Hospital, Florence, Italy; <SUP>d</SUP>Microbiology and Virology Unit, A. Manzoni Hospital, Lecco, Italy; <SUP>e</SUP>Microbiology and Virology Unit, Santa Maria alle Scotte University Hospital, Siena, Italy


Acquired metallo-β-lactamases (MBLs) are resistance determinants of increasing clinical importance in Gram-negative bacterial pathogens, which confer a broad-spectrum β-lactam resistance including carbapenems. Several such enzymes have been described since the 1990s. In this work a novel acquired MBL, named FIM-1, was identified and characterized. The bla<SUB>FIM-1</SUB> gene was cloned from a multidrug-resistant Pseudomonas aeruginosa clinical isolate (FI-14/157) cultured from a patient with a vascular graft infection in Florence, Italy. The isolate belonged in the sequence type 235 epidemic clonal lineage. The FIM-1 enzyme is a member of subclass B1 and, among acquired MBLs, exhibited the highest similarity (around 40% amino acid identity) with NDM-type enzymes. In P. aeruginosa FI-14/157 the bla<SUB>FIM-1</SUB> gene was apparently inserted into the chromosome and associated with ISCR19-like elements that were likely involved in the capture and mobilization of this MBL gene. Transfer experiments of the bla<SUB>FIM-1</SUB> gene to an Escherichia coli or another P. aeruginosa strain by conjugation or electrotransformation were not successful. The FIM-1 protein was produced in Escherichia coli and purified by two chromatography steps. Analysis of the kinetic parameters, carried out with the purified enzyme, revealed that FIM-1 has a broad substrate specificity, with preference for penicillins (except the 6α-methoxy derivative temocillin) and carbapenems. Aztreonam was not hydrolyzed. Detection of this novel type of acquired MBL in a P. aeruginosa clinical isolate underscores the increasing diversity of such enzymes that can be encountered in the clinical setting.


#Address correspondence to: Gian Maria Rossolini, Department of Biotecnologies, Section of Microbiology, University of Siena, Policlinico Santa Maria alle Scotte, Viale Bracci, I-53100 Siena, Italy. Tel: +39-0577-233455; Fax: +39-0577-233870; e-mail: gianmaria.rossolini@unisi.it

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