Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8964055 | Diagnostic Microbiology and Infectious Disease | 2018 | 25 Pages |
Abstract
We evaluated the genetic environment of blaGES-16 found in 2 carbapenem-resistant Serratia marcescens clinical isolates recovered from patients hospitalized at a tertiary hospital located in Rio de Janeiro, Brazil. We also compared the kinetics constants for GES-16 and GES-5 against several β-lactams. Both S. marcescens isolates showed identical PFGE pattern and carried the carbapenemase-encoding gene blaGES-16 and the extended-spectrum β-lactamase encoding gene blaOXA-10. The blaGES-16 was inserted at the first position of a defective class 1 integron, composed by a fragmented integrase gene that lacked its attI1 recombination site, followed by dfr22, aac(6â²)-IIc, and aadA1 genes. This integron was located on a 30-kb nonconjugative plasmid. The GES-16 showed 2 amino acid substitutions (Gln38Glu and Gly170Ser) compared to GES-1. Kinetic analysis showed that GES-16 presented hydrolytic activity against all β-lactams tested, except for aztreonam. Imipenem was the carbapenem more efficiently hydrolyzed (highest kcat/Km) by GES-16. The kinetic parameters of GES-16 were similar to those of GES-5. In conclusion, we identified a new GES-type enzyme with carbapenemase activity in S. marcescens. The increasing diversity of such resistance determinants confirms the ongoing evolution of these β-lactamases towards a broader spectrum of activity.
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Authors
Ana Paula Streling, Paula P. Barbosa, Marcelo F. Marcondes, Adriana G. Nicoletti, Renata C. Picão, Elisa C. Pinto, Elizabeth A. Marques, Vitor Oliveira, Ana C. Gales,