Diversity of Clavulanic Acid-Inhibited Extended-Spectrum β-Lactamases in Aeromonas spp. from the Seine River, Paris, France

Abstract

Environmental Aeromonas sp. isolates resistant to ceftazidime were recovered during an environmental survey performed with water samples from the Seine River, in Paris, France, in November 2009. Selected isolates were identified by sequencing of the 16S rRNA and rpoB genes. PCR and cloning experiments were used to identify broad-spectrum-␤-lactamase-encoding genes and their genetic context. Clavulanic acid-inhibited extended-spectrum-␤-lactamase (ESBL) genes were identified in 71% of the Aeromonas sp. isolates. A variety of ESBL genes were detected, including bla VEB-1a , bla SHV-12 , bla PER-1 , bla PER-6 , bla TLA-2 , and bla GES-7 , suggesting an aquatic reservoir of those ESBL genes. Moreover, the repeated elements and different insertion sequences were identified in association with the bla PER-6 and the bla VEB-1a genes, respectively, indicating a wide diversity of mobilization events, making Aeromonas spp. a vehicle for ESBL dissemination.Bacteria with intrinsic or acquired resistance to antibiotics are commonly found in aquatic environments, where Pseudomonas, Serratia, and Aeromonas are commonly identified (2,17). Recent studies reported that the bla TEM-1 gene was detected in most of the Gram-negative isolates resistant to ampicillin recovered from lakes in Brazil or from wastewater treatment plants in China (24,40). Furthermore, several studies identified extended-spectrum ␤-lactamases (ESBLs) from water samples. For instance, the clinically relevant ESBL PER-1 was identified from Aeromonas media in a Swiss lake (32), and CTX-M-14 and TEM-52 were detected in Escherichia coli recovered from a South Korean river (21). Besides, nonclinically relevant Ambler class A ␤-lactamases TLA-2 and PER-6 were identified from uncultured bacteria (43,12) and Aeromonas allosaccharophila isolates, respectively (15).In addition, other studies reported on the identification of carbapenem-hydrolyzing ␤-lactamases in the environment, such as the Ambler class A ␤-lactamases IMI-2 and BIC-1 from Enterobacter asburiae (1, 5) and Pseudomonas fluorescens (14), respectively; the Ambler class B ␤-lactamase VIM-2 from Pseudomonas pseudoalcaligenes (41); and the class D ␤-lactamase OXA-23 from Acinetobacter baumannii (13).The present study was designed to evaluate the diversity of broad-spectrum ␤-lactam resistance determinants in Aeromonas species in water samples from the Seine River, Paris, France. The working hypothesis was that Aeromonas spp. could be an important reservoir for ESBLs. MATERIALS AND METHODSBacterial strains and plasmids. Three water samples (100 ml) were collected from approximately 0.2 m below the water surface in sterile bottles in November 2009 and filtered through nitrocellulose membranes (pore size, 0.45 m; Millipore), and the filters were resuspended in 3 ml of sterile water. Aliquots (0.1 ml) were plated on MacConkey agar plates supplemented with ceftazidime (2 g/ ml), and 10-fold dilutions were plated (0.1 ml) in parallel on antibiotic-free MacConkey agar plates for bacterial counts. Samples were proces...

Resistance to Broad-Spectrum Antibiotics in Aquatic Systems: Anthropogenic Activities Modulate the Dissemination of bla CTX-M -Like Genes

“…isolates and was found more frequently among isolates from polluted sites. Recently, in several environmental studies, members of the same genera have been identified as ESBL producers, enforcing their relevance and importance for resistance monitoring (14,15,27). We investigated the presence of different ESBL genes and found bla CTX-M genes to be the most prevalent, followed by bla TEM genes.…”

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

“…The number of studies investigating rivers as potential reservoirs of ESBL producers is still very limited (19,20,21,22,23), and data from only one river (Seine River, Paris, France) in central Europe are available (22). Rivers and lakes are considered especially relevant as putative reservoirs of multiresistant bacteria, since they collect surface waters containing materials from different origins, e.g., wastewater plants, water of urban or industrial effluents, agricultural activities, or rain.…”

Scientific Opinion on the public health risks of bacterial strains producing extended-spectrum β-lactamases and/or AmpC β-lactamases in food and food-producing animals

“…Phage-related elements are associated with bla CTX-M genes (Oliver et al, 2005) and Re1-like sequences have been identified in association with bla VEB-like and bla PER genes (Girlich et al, 2011).…”

“…ESBLs (CTX-M, PER) and/or AmpC (CMY-2) enzymes have been detected among potential human and fish pathogens in these settings, such as Salmonella, Aeromonas, Vibrio, and Edwarsiella ictaluri (Doublet et al, 2009;Girlich et al, 2010Girlich et al, , 2011McIntosh et al, 2008;Picao et al, 2008;Welch et al, 2009). …”