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R Canton

Publications and source records attributed to R Canton.

7 recordsLinked to original sources
PubMed1995

New extended-spectrum TEM-type beta-lactamase from Salmonella enterica subsp. enterica isolated in a nosocomial outbreak.

A new extended-spectrum beta-lactamase was detected in a lactose-positive Salmonella enterica subsp. enterica strain that caused a nosocomial outbreak involving eight patients in a pediatric cardiology unit. This strain showed high levels of resistance to ceftazidime and aztreonam and relatively low levels of resistance to cefotaxime and ceftriaxone. Resistance was associated with a conjugative plasmid of 59 kb, which encoded a new beta-lactamase with an isoelectric point of 5.9 that strongly hydrolyzed ceftazidime and to a much lesser extent hydrolyzed cefotaxime. The enzyme activity was inhibited by clavulanate. The corresponding bla gene was cloned and sequenced. The deduced amino acid sequence showed three significant amino acid replacements with respect to the TEM-1 sequence: Arg-164-->His, Glu-240-->Lys, and Thr-265-->Met. This combination is unique among extended-spectrum beta-lactamases and served to characterize the new enzyme, TEM-27.

Amino Acid Sequence↗
PubMed1993

Characterization of a new TEM-type beta-lactamase resistant to clavulanate, sulbactam, and tazobactam in a clinical isolate of Escherichia coli.

A clinical Escherichia coli strain highly resistant to the combinations of amoxicillin-clavulanate, ampicillin-sulbactam, and piperacillin-tazobactam was isolated from a patient with a community-acquired urinary tract infection who was previously treated with amoxicillin-clavulanate. These resistances were carried by a 45-kb conjugative plasmid encoding for a single beta-lactamase with a pI of 5.4. Cloning and sequencing of the new beta-lactamase, IRT-3, revealed identity with the blaT1 gene encoding the TEM-1 beta-lactamase except for a replacement of the methionine residue at position 67 by isoleucine and of the methionine residue at position 180 by threonine. Both mutations were segregated by the construction of hybrid genes, and only the mutation at methionine at position 67 was related to resistance to the suicide inhibitors. The inhibitory effects of clavulanate, sulbactam, and tazobactam on the TEM-1 enzyme were substantially decreased in comparison with those on IRT-3, as indicated by the 50% inhibitory concentrations.

Clavulanic Acid↗
PubMed1991

The incidence and beta-lactam resistance of Proteus vulgaris in hospital infections: the last decade.

During the period of 1980-1990, 581 Proteus vulgaris strains were obtained in a general hospital. They were considered as the significant isolate in 0.6% of soft tissue infections, 0.6% of urinary tract infections and in 0.2% of bacteremic episodes. Sixty-three percent of the 393 tested strains showed resistance to ampicillin, cefazolin and cefamandole or cefuroxime. About 7% were susceptible to all beta-lactam drugs, and showed a very low beta-lactamase activity and 5% of the strains showed a phenotype of resistance including ampicillin, carbenicillin-ticarcillin, cefazolin and cefamandole or cefuroxime, and presented increased chromosomal beta-lactamase activity. Cefotaxime-resistance was detected in 2% of the isolates which appeared in the period 1987-1990.

Ampicillin Resistance↗