Aminoglycoside resistance genes aph(2")-Ib and aac(6')-Im detected together in strains of both Escherichia coli and Enterococcus faecium.
Escherichia coli SCH92111602 expresses an aminoglycoside resistance profile similar to that conferred by the aac(6')-Ie-aph(2")-Ia gene found in gram-positive cocci and was found to contain the aminoglycoside resistance genes aph(2")-Ib and aac(6')-Im (only 44 nucleotides apart). aph(2")-Ib had been reported previously in Enterococcus faecium SF11770. aac(6')-Im had not been detected previously in enterococci and was found to be present also 44 nucleotides downstream from aph(2")-Ib in E. faecium SF11770. aph(2")-Ib and aac(6')-Im are separate open reading frames, each with its own putative ribosome binding site, whereas aac(6')-Ie-aph(2")-Ia appears to be a fusion of two genes with just one start and one stop codon. The deduced AAC(6')-Im protein exhibits 56% identity and 80% similarity to the AAC(6')-Ie domain of the bifunctional enzyme AAC(6')-APH(2"). Our results document the existence of a member of the aph(2") family of genes in gram-negative bacteria and provide evidence suggesting the horizontal transfer of aph(2")-Ib and aac(6')-Im as a unit between gram-positive and gram-negative bacteria.
Chow
J W
JW
Research and Medical Service, John D. Dingell VA Medical Center, 4646 John R, Detroit, MI 48201-2097, USA. JChow@wayne.edu
Kak
V
V
You
I
I
Kao
S J
SJ
Petrin
J
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Clewell
D B
DB
Lerner
S A
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Miller
G H
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Shaw
K J
KJ
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins; D004351:Drug Resistance / Q000235:genetics; D016984:Enterococcus faecium / Q000187:drug effects / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D008826:Microbial Sensitivity Tests; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics*
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); C439343:aac(6')-Im protein, Enterococcus faecium; C415966:aph(2')-Ib protein, Enterococcus faecium