Gert van der Hoek
In Memoriam - Editor, Senior Moderator
First Reported Case of New Delhi Metallo (NDM) Carbapenem-Positive Gene in Escherichia coli from Companion Animals in the United States
Tuesday, Sep 11, 2012
Abstract: Background: Carbapenems are used to treat serious infectious caused by gram-negative bacteria. Resistance to carbapenems is mediated by the production of Class A, D, and B metallo-β-lactamase enzymes (MBLs). This study characterized the prevalence of genes producing New Delhi metallo (NDM)-β-lactamases in Escherichia coli isolates from companion animals in the United States.
Methods: Antimicrobial susceptibility was determined for canine and feline clinical E. coli isolates collected from veterinary laboratories throughout the US between 2008 and 2009. Isolates (n=100) which exhibited reduced susceptibility to ceftazidine or cefotaxime (MIC≥16 µg/ml) or meropenem (MIC≥1 µg/ml) were analyzed. The presence of genes encoding for carbapenemases (blaKPC, blaNDM, blaAIM, blaGIM, blaSIM, blaDIM, blaIMP, blaVIM, blaSPM and blaOXA-48) were investigated by PCR. PCR amplicons were sequenced and BLASTed to confirm the gene identity. Plasmid analysis by S1 nuclease-PFGE, Southern hybridization, and conjugation experiments were performed on all NDM-positive isolates.
Results: PCR and sequencing identified the presence of blaNDM gene in six E. coli isolates. Other carbapenemases encoding genes were not detected. The meropenem MIC values for NDM producing isolates ranged from 0.5 to 16 µg/ml. NDM-positive isolates (n=6) were also resistant to doxycycline (n=2), enrofloxacin (n=2), trimethoprim/sulfamethoxazole (n=1) or gentamicin (n=2). An isolate successfully conjugated with a recipient strain, E. coli J53 AZr, with ampicillin selection, and the resulting transconjugant that exhibited resistance to meropenem (MIC 4 µg/ml). PCR and DNA sequencing confirmed the presence of blaNDM gene in the transconjugant. The transconjugant also exhibited resistance to cefazolin, cefotaxime, cefpodoxime, ceftiofur, ceftriaxone, cephalothin, and cefoxitin. NDM encoding gene (blaNDM) was detected by Southern hybridization in plasmid DNA (30 kb to 150 kb) from the NDM-positive isolates.
Conclusions: This work highlights the first reported case of NDM carbapenemases-positive gene in E. coli from companion animals in the United States.
OASIS
Thanks to Maryn McKenna
More details and usefull comment in Maryn McKenna's blog.
Tuesday, Sep 11, 2012
Abstract: Background: Carbapenems are used to treat serious infectious caused by gram-negative bacteria. Resistance to carbapenems is mediated by the production of Class A, D, and B metallo-β-lactamase enzymes (MBLs). This study characterized the prevalence of genes producing New Delhi metallo (NDM)-β-lactamases in Escherichia coli isolates from companion animals in the United States.
Methods: Antimicrobial susceptibility was determined for canine and feline clinical E. coli isolates collected from veterinary laboratories throughout the US between 2008 and 2009. Isolates (n=100) which exhibited reduced susceptibility to ceftazidine or cefotaxime (MIC≥16 µg/ml) or meropenem (MIC≥1 µg/ml) were analyzed. The presence of genes encoding for carbapenemases (blaKPC, blaNDM, blaAIM, blaGIM, blaSIM, blaDIM, blaIMP, blaVIM, blaSPM and blaOXA-48) were investigated by PCR. PCR amplicons were sequenced and BLASTed to confirm the gene identity. Plasmid analysis by S1 nuclease-PFGE, Southern hybridization, and conjugation experiments were performed on all NDM-positive isolates.
Results: PCR and sequencing identified the presence of blaNDM gene in six E. coli isolates. Other carbapenemases encoding genes were not detected. The meropenem MIC values for NDM producing isolates ranged from 0.5 to 16 µg/ml. NDM-positive isolates (n=6) were also resistant to doxycycline (n=2), enrofloxacin (n=2), trimethoprim/sulfamethoxazole (n=1) or gentamicin (n=2). An isolate successfully conjugated with a recipient strain, E. coli J53 AZr, with ampicillin selection, and the resulting transconjugant that exhibited resistance to meropenem (MIC 4 µg/ml). PCR and DNA sequencing confirmed the presence of blaNDM gene in the transconjugant. The transconjugant also exhibited resistance to cefazolin, cefotaxime, cefpodoxime, ceftiofur, ceftriaxone, cephalothin, and cefoxitin. NDM encoding gene (blaNDM) was detected by Southern hybridization in plasmid DNA (30 kb to 150 kb) from the NDM-positive isolates.
Conclusions: This work highlights the first reported case of NDM carbapenemases-positive gene in E. coli from companion animals in the United States.
OASIS
Thanks to Maryn McKenna
More details and usefull comment in Maryn McKenna's blog.