Novel ambler class A carbapenem-hydrolyzing beta-lactamase from a Pseudomonas fluorescens isolate from the Seine River, Paris, France

Abstract

A Pseudomonas fluorescens isolate (PF-1) resistant to carbapenems was recovered during an environmental survey performed with water from the Seine River (Paris). It expressed a novel Ambler class A carbapenemase, BIC-1, sharing 68 and 59% amino acid identities with beta-lactamases SFC-1 from Serratia fonticola and the plasmid-encoded KPC-2, respectively. beta-Lactamase BIC-1 hydrolyzed penicillins, carbapenems, and cephalosporins except ceftazidime and monobactams. The bla(BIC-1) gene was chromosomally located and was also identified in two other P. fluorescens strains isolated from the Seine River 3 months later.

FIG. 1.

Amino acid sequence comparison of BIC-1 with those of SFC-1 from S. fonticola (5) and KPC-2 from K. oxytoca (27). Full stops indicate the gaps that were inserted to optimize the alignment, and dashes indicate residues identical to those of BIC-1. The numbering is according to the method described by Ambler et al. (1). The conserved domains of class A β-lactamases are underlined (6). The residues suggested to play a critical role in carbapenemase activity are marked by asterisks (13, 15). The arrow indicates the cleavage site for the leader peptide of BIC-1.

FIG. 2.

Dendrogram obtained for 13 representative class A β-lactamases by neighbor-joining analysis. The alignment used for the tree calculation was performed with the ClustalX program. Branch lengths are drawn to scale and are proportional to the number of amino acid changes. The distance along the vertical axis has no significance. Numbers in parentheses indicate percentages of amino acid identity with the β-lactamase BIC-1. The β-lactamases (GenBank accession numbers indicated) are CARB-2 (Q0370), TEM-1 (AAG47772), SHV-1 (AAD18054), VEB-1 (AAK14293), PER-1 (CAF18433), CTX-M-1 (CAJ01342), KPC-2 (AAO53443), SFC-1 (AAR06587), SME-1 (CAA82281), NMC-A (CAA79967), GES-1 (AAL82589), and BEL-1 (AAZ04368).