LEFLON V, HEYM B, NICOLAS-CHANOINE MH; Interscience Conference on Antimicrobial Agents and Chemotherapy.

Abstr Intersci Conf Antimicrob Agents Chemother Intersci Conf Antimicrob Agents Chemother. 1999 Sep 26-29; 39: 138 (abstract no. 2052).

Ambroise Pare Univ.-Hosp., Boulogne, FRANCE.

Twenty two E. coli isolates which were collected in 8 French hospitals in 1998, were presumed to be producing IRT enzymes on the basis of the inhibition diameters of the following Beta-lactam antibiotics: amoxicillin/clavulanate, ticarcillin, ticarcillin/clavulanate, mecillinam, cephalothin and cefepime. IRT encoding genes were PCR-amplified, and the sequence of structural genes and of the promoter regions were determined. The aminoacid substitutions (aa-sub) observed in these IRT allowed us to identify 18 IRT previously described, IRT1 (n=1), IRT2 (n=3), IRT4 (n=1), IRT6 (n=1), IRT7 (n=1), IRT8 (n=3), IRT10 (n=3) and IRT11 (n=5), and 4 new IRT. The encoding gene of the first new IRT was identical to bla[TEM1b] except two mutations, A407C and C929A leading to the aa-sub Met69Leu and Arg244Ser, respectively. The gene of the second new IRT had a sequence identical to that of bla[TEM36] (IRT7) except the mutation T695C leading to an additionnal aa-sub Trp165Arg. The gene of the third new IRT which was most likely derived from bla[TEM1b] displayed the mutation C929G leading to the aa-sub Arg244Gly. The gene of the fourth IRT was identical to bla[TEM1b] except the mutation A590G resulting in the aa-sub Ser130Gly. In addition to these new IRT, different silent mutations have been found in almost all genes encoding IRT corresponding to previously described IRT. Moreover, C32T and G162T, known to be involved in the creation of a strong promoter, have been found in the genes of our IRT6 and one of our IRT2 (C32T), and in the genes of our two remaining IRT2 (G162T). This systematic study of IRT encoding genes showed, beyond the occurrence of new silent point mutations, the appearance of new IRT enzymes due to new aa-sub or new aa-sub associations.

Publication Types:

• Meeting Abstracts

Keywords:

• Amdinocillin
• Amoxicillin
• Cephalothin
• Clavulanic Acid
• Escherichia coli
• Escherichia coli Infections
• Polymerase Chain Reaction
• Promoter Regions (Genetics)
• Ticarcillin
• beta-Lactamases
• genetics

Other ID:

• GWAIDS0007445

UI: 102244941

From Meeting Abstracts