Article (Scientific journals)
Aminoglycoside 6 '-N-Acetyltransferase Variants Of The Ib Type With Altered Substrate Profile In Clinical Isolates Of Enterobacter Cloacae And Citrobacter Freundii
Casin, I.; Bordon, F.; Bertin, P. et al.
1998In Antimicrobial Agents and Chemotherapy, 42 (2), p. 209-215
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Abstract :
[en] Three clinical isolates, Enterobacter cloacae EC1562 and EC1563 and Citrobacter freundii CFr564, displayed an aminoglycoside resistance profile evocative of low-level 6'-N acetyltransferase type II [AAC(6')-II] production, which conferred reduced susceptibility to gentamicin but not to amikacin or isepamicin. Aminoglycoside acetyltransferase assays suggested the synthesis in the three strains of an AAC(6') which acetylated amikacin practically as well as it acetylated gentamicin in vitro. Both compounds, however, as well as isepamicin, retained good bactericidal activity against the three strains. The aac genes were borne by conjugative plasmids (pLMM562 and pLMM564 of ca. 100 kb and pLMM563 of ca. 20 kb). By PCR mapping and nucleotide sequence analysis, an aac(6')-Ib gene was found in each strain upstream of an ant(3")-I gene in a sulI-type integron. The size of the AAC(6')-Ib variant encoded by pLMM562 and pLMM564, AAC(6')-Ib7, was deduced to be 184 (or 177) amino acids long, whereas in pLMM563 a 21-bp duplication allowing the recruitment of a start codon resulted in the translation of a variant, AAC(6')-Ib8, of 196 amino acids, in agreement with size estimates obtained by Western blot analysis. Both variants had at position 119 a serine instead of the leucine typical for the AAC(6')-Ib variants conferring resistance to amikacin. By using methods that predict the secondary structure, these two amino acids appear to condition an alpha-helical structure within a putative aminoglycoside binding domain of AAC(6')-Ib variants.
Disciplines :
Biochemistry, biophysics & molecular biology
Author, co-author :
Casin, I.
Bordon, F.
Bertin, P.
Coutrot, A.
Podglajen, I.
Brasseur, Robert ;  Université de Liège - ULiège > Gembloux Agro-Bio Tech
Collatz, E.
Language :
English
Title :
Aminoglycoside 6 '-N-Acetyltransferase Variants Of The Ib Type With Altered Substrate Profile In Clinical Isolates Of Enterobacter Cloacae And Citrobacter Freundii
Publication date :
1998
Journal title :
Antimicrobial Agents and Chemotherapy
ISSN :
0066-4804
eISSN :
1098-6596
Publisher :
American Society for Microbiology, Washington, United States - District of Columbia
Volume :
42
Issue :
2
Pages :
209-215
209-15
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 25 June 2010

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