Waterborne infection caused by a carbapenem-resistant Enterobacter asburiae isolate producing the class A carbapenemase IMI-2 in France
Abstract number: P1497
Poirel L., Spicq C., Bernabeu S., Durand P., Nordmann P.
Objectives: Two Enterobacter spp. isolates were recovered from a 2-years-old child hospitalised after a drowning accident that occurred in a private pond in September 2007 in France. Enterobacter spp. MON-1 was isolated from a tracheal aspiration and showed a wild-type phenotype of resistance to b-lactams. Enterobacter spp. MON-2 was from urine and resistant to carbapenems but susceptible to ceftazidime. A peculiar synergy was noticed between clavulanic-acid and imipenem. The aim of the study was to identify the mechanism(s) responsible for carbapenem resistance in isolate MON-2.
Methods: Genomic DNA Enterobacter spp. isolates MON-1 and MON-2 were extracted and used as template for PCR screening of known carbapenemase genes. Plasmids were extracted using the Kieser technique. Mating-out assays were performed using E. coli J53 as recipient strain and a selection with amoxicillin (50 mg/L)- and azide (100 mg/L)-containing media. Random-amplified polymorphism detection (RAPD) techique was used to compare genotypically both isolates. Amplification and sequencing of 16S RNA and blaampC genes were used to identify at the genetic level the Enterobacter species.
Results: Molecular techniques showed that both Enterobacter spp. isolates belonged to the Enterobacter asburiae species. RAPD analysis showed that isolates MON-1 and MON-2 were clonally-related. E. asburiae MON-2 expressed the clavulanic-acid inhibited and carbapenem-hydrolyzing Ambler class A b-lactamase IMI-2. Mating-out assays remained unsuccessful but electroporation of a plasmid extract led to Escherichia coli transformant carrying a 150-kb blaIMI-2-positive plasmid that did not provide any other antibiotic co-resistance marker. Induction experiments and PCR mapping identified a LysR-type blaIMI-R2 regulatory gene upstream of the blaIMI-2 gene.
Conclusion: This study identified a class A carbapenemase of the IMI-type for the first time in Europe, after the identification of IMI-1 and IMI-2 in Enterobacter cloacae isolates in USA and China, respectively. This study further identifies the aquatic reservoir as a source of IMI-like producers.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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