ISSN:
1432-1432
Keywords:
Key words: Amoxicillin-clavulanate resistance —blaTEM—blaIRT— RFLP linkage group — Sequence framework —Convergent evolution
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract. The molecular diversity of inhibitor-resistant TEM (IRT) enzymes was explored using a strategy which involved DNA amplification by polymerase chain reaction (PCR), analysis of restriction fragment length polymorphism (RFLP), and direct nucleotide sequencing. The study of plasmid-borne genes from 27 strains, resistant to amoxicillin and β-lactamase-inhibitor combinations, identified mutations resulting in amino acid change at positions 69, 244, 275, and 276 known to be associated with the IRT phenotype and a mutation at nucleotide position 162 in the promoter region. These mutations were found to lie on two different gene sequences, described here as ``TEM-1B like'' and ``TEM-2 like'' restriction linkage groups. Further analysis, of nucleotide sequences of promoter and coding regions of the β-lactamases, confirmed that a given mutation causing IRT phenotype could be associated with two different gene sequence frameworks and two different causal mutations could lie on identical gene sequence framework. These data argue in favor of convergent phenotypic evolution of IRT enzymes under the selective pressure imposed by the intensive clinical use of β-lactam–β-lactamase inhibitor combinations.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00006121
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