Novel Ambler Class A Carbapenem-Hydrolyzing β-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 ␤-lactamases SFC-1 from Serratia fonticola and the plasmid-encoded KPC-2, respectively. ␤-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.Pseudomonas fluorescens is a psychrotrophic bacterium that expresses a chromosomally encoded and inducible Ambler class C ␤-lactamase (10, 15). Carbapenemases (serine-or metallo-␤-lactamases) remain the most common mechanism of resistance to carbapenems in Gram-negative organisms (22,23). To date, most acquired metallo-␤-lactamase (MBL)-encoding genes (bla IMP or bla VIM variants) have been reported from Pseudomonas aeruginosa and very rarely from P. fluorescens (8, 12). Class A carbapenemases are either chromosome encoded or plasmid encoded and remain rarely identified in Gram-negative organisms. Indeed, several class A carbapenemases are chromosomally encoded (NMC-A, SFC-1, SME-1 to -3, IMI-1), with the exception of the emerging KPC ␤-lactamases, which are plasmid encoded (24). The chromosomal location of the bla SFC-1 gene could be the result of a horizontal gene transfer into an environmental Serratia fonticola isolate (5). The bla SME genes from Serratia marcescens are presumed to be chromosomal. Genes encoding NMC-A and IMI ␤-lactamases have been found sporadically, either in clinical or in environmental isolates of Enterobacter cloacae and Enterobacter asburiae from rivers (2). The bla NMC-A gene was found chromosomally located in several clinical isolates. The bla IMI-1 gene was chromosomally located, whereas the bla IMI-2 genes were identified on plasmids. The imiR-imi-2 gene tandem in E. cloacae and E. asburiae appeared to be flanked by transposable elements (2). Class A carbapenemases such as GES-2, GES-5, and KPC-2 have been recently reported from P. aeruginosa (16) but not from other Pseudomonas species.Here, we characterize a novel class A carbapenemase identified from a P. fluorescens environmental isolate. This identification occurred during a survey aimed to study the spread of multidrug-resistant Gram-negative organisms in the environment. MATERIALS AND METHODSBacterial strains and plasmids. P. fluorescens isolate PF-1 was recovered from a water sample from the Seine River in downtown Paris. Water samples (100 ml) were collected in sterile bottles in January 2009 and filtered through nitrocellulose membranes (0.45-m pore size; Millipore), and the filters were resuspended in 1 ml of sterile water. Aliquots (0.1 ml) were plated on MacConkey agar plates supplemented with imipenem (1 g/ml), whereas 10-fold dilutions (0.1 ml) were plated on antibiotic-free MacConkey agar plates for bacterial count...

Characteristics of Extended-Spectrum β-Lactamase- and Carbapenemase-Producing Enterobacteriaceae Isolates from Rivers and Lakes in Switzerland

“…OXA-48 is of particular concern, because it appears to have become the most important type in central Europe. Carbapenemase-producing strains have hitherto been detected in rivers in the United States (38), China (20), France (39), and Portugal (40), indicating that a global environmental dissemination is currently ongoing.…”

Elucidating the role of Trp105 in the KPC‐2 β‐lactamase

“…1,2 However, the recent emergence of class A b-lactamases capable of hydrolyzing carbapenems threatens this class of b-lactam antibiotics. [3][4][5][6] One of these blactamases, KPC-2, is becoming a major healthcare threat in the United States and throughout the world. 5,7,8 KPC-2 manifests a very broad substrate profile including penicillins, extended-spectrum cephalosporins, cephamycins, and carbapenems.…”

A Structure-Based Classification of Class A β-Lactamases, a Broadly Diverse Family of Enzymes

“…4 and 5): 64ERFPLC SSFKGFLAAAVL81, 160FRLDRWELE/DLNT/SAIPGDxRDTST /SP183, and 231VGDKTGT/SCGxYGTANDYAVxWP252. These enzymes have conserved cysteine residues at positions 69 and 238, with the formation of a disulfide bridge that modifies the shape of the active site through changes in the distances between several active-site residues (21). The disulfide bridge is essential for the hydrolysis of carbapenems, penicillins, and cephalosporins.…”