Chromosomal origin of acetyltransferase AAC(6') specifying amikacin resistance in Serratia marcescens.
Two clinical isolates of Serratia marcescens resistant to aminoglycoside-aminocyclitols and other antibiotics have been examined for aminoglycoside-modifying enzymes. Both strains were amikacin-resistant, and this resistance was mediated by an acetyltransferase AAC(6'). S. marcescens 737 contains a single conjugative plasmid, pUZ 737, of 135 kilobases, which confers resistance to gentamicin and tobramycin by a nucleotidyltransferase, ANT(2"), and to kanamycin, neomycin, butirosin and lividomycin by a phosphotransferase, APH(3'). S. marcescens 1830 does not contain extrachromosomal DNA, and it produced only the above mentioned AAC(6'). The presence of AAC(6') and associated aminoglycoside resistance are not dependent on the presence of a detectable plasmid, not transferred by conjugation, and not cured. Therefore, this enzyme is probably encoded by a chromosomal gene.
Gómez-Lus
R
R
Department of Microbiology, School of Medicine, Zaragoza, Spain.
Rivera
M J
MJ
Bobey
D
D
Martín
C
C
Navarro
M
M
D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism*; D000583:Amikacin / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002876:Chromosomes, Bacterial / Q000201:enzymology*; D004352:Drug Resistance, Microbial / Q000235:genetics; D010957:Plasmids / Q000235:genetics; D012706:Serratia marcescens / Q000187:drug effects / Q000201:enzymology / Q000235:genetics* / Q000648:ultrastructure
D000900:Anti-Bacterial Agents; D000583:Amikacin; D000123:Acetyltransferases; C056532:aminoglycoside N(6')-acetyltransferase