CTX-M-type extended-spectrum beta-lactamase that hydrolyzes ceftazidime through a single amino acid substitution in the omega loop
| Autor: | Laurent Poirel, Isabelle Le Thomas, Amal Karim, Patrice Nordmann, Edouard Bingen, Thierry Naas |
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| Rok vydání: | 2001 |
| Předmět: |
DNA
Bacterial Cefotaxime Klebsiella pneumoniae Molecular Sequence Data Ceftazidime Microbial Sensitivity Tests Biology medicine.disease_cause beta-Lactamases Microbiology Mechanisms of Resistance medicine Pharmacology (medical) Amino Acid Sequence Escherichia coli Peptide sequence Antibacterial agent Pharmacology Reverse Transcriptase Polymerase Chain Reaction Omega loop Genetic transfer biology.organism_classification Recombinant Proteins Cephalosporins Kinetics Infectious Diseases Amino Acid Substitution Hybridization Genetic medicine.drug Plasmids |
| Zdroj: | Antimicrobial agents and chemotherapy. 45(12) |
| ISSN: | 0066-4804 |
| Popis: | Escherichia coli ILT-1, Klebsiella pneumoniae ILT-2, and K. pneumoniae ILT-3 were isolated in May 1999 in Paris, France, from a rectal swab of a hospitalized 5-month-old girl. These isolates had a clavulanic acid-inhibited substrate profile that included expanded-spectrum cephalosporins. The MICs of cefotaxime were higher for E. coli ILT-1 and K. pneumoniae ILT-2 than for K. pneumoniae ILT-3, while the opposite was found for the MICs of ceftazidime. Genetic and biochemical analyses revealed that E. coli ILT-1 and K. pneumoniae ILT-2 produced the CTX-M-18 β-lactamase, while K. pneumoniae ILT-3 produced the CTX-M-19 β-lactamase. The amino acid sequence of the CTX-M-18 β-lactamase differed from that of the CTX-M-9 β-lactamase by an Ala-to-Val change at position 231, while CTX-M-19 possessed an additional Pro-to-Ser change at position 167 in the omega loop of Ambler class A enzymes. The latter amino acid substitution may explain the CTX-M-19-mediated hydrolysis of ceftazidime, which has not been reported for other CTX-M-type enzymes. The bla CTX-M-18 and bla CTX-M-19 genes were located on transferable plasmids that varied in size (ca. 60 and 50 kb, respectively) but that showed similar restriction patterns. |
| Databáze: | OpenAIRE |
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