Characterization of class 1 integrons from Pseudomonas aeruginosa that contain the bla(VIM-2) carbapenem-hydrolyzing beta-lactamase gene and of two novel aminoglycoside resistance gene cassettes
L. Poirel et al., Characterization of class 1 integrons from Pseudomonas aeruginosa that contain the bla(VIM-2) carbapenem-hydrolyzing beta-lactamase gene and of two novel aminoglycoside resistance gene cassettes, ANTIM AG CH, 45(2), 2001, pp. 546-552
Two clonally unrelated Pseudomonas aeruginosa clinical strains, RON-1 and R
ON-2, were isolated in 1997 and 1998 from patients hospitalized in a suburb
of Paris, France. Both isolates expressed the class B carbapenem-hydrolyzi
ng beta -lactamase VIM-2 previously identified in Marseilles in the French
Riviera. In both isolates, the bla(VIM-2) cassette was part of a class 1 in
tegron that also encoded aminoglycoside-modifying enzymes. In one case, two
novel aminoglycoside resistance gene cassettes, aacA29a and aacA29b, were
located at the 5' and 3' end of the bla(VIM-2) gene cassette, respectively.
The aacA29a and aacA29b gene cassettes were fused upstream with a 101-bp p
art of the 5' end of the qacE cassette. The deduced amino acid sequence AAC
(6')-29a protein shared 96% identity with AAC(6')-29b but only 34% identity
with the aacA7-encoded,WC(6')-II, the closest relative of the AAC(6')-I fa
mily enzymes. These aminoglycoside acetyltransferases had amino acid sequen
ces much shorter (131 amino acids) than the other AAC(6')-I enzymes (144 to
153 amino acids). They conferred resistance to amikacin, isepamicin, kanam
ycin, and tobramycin but not to gentamicin, netilmicin, and sisomicin.