Evidence for a chromosomal site specifying amikacin resistance in multiresistant Serratia marcescens.
We studied 21 strains of amikacin-resistant Serratia marcescens from three different U.S. cities, Twenty of the 21 strains contained conjugative R plasmids mediating gentamicin and tobramycin resistance. Amikacin-resistant S. marcescens from two cities predominated in protracted outbreaks. Conversely, the amikacin-resistant Charleston strain (serotype 02/03:nonmotile) was isolated from only four patients during an outbreak of gentamicin- and tobramycin resistant, amikacin-susceptible S. marcescens (serotype O19:O17). Five different representative amikacin-resistant S. marcescens, each containing a single conjugative plasmid, elaborated a nontransferable aminoglycoside (6')-N-acetyltransferase [AAC(6')] with similar substrate profiles in addition to other transferable aminoglycoside-modifying enzymes. One amikacin-resistant S. marcescens cured of its plasmid and another naturally occurring plasmid-free amikacin-resistant S. marcescens elaborated only AAC(6')-1. These data support the concept of a chromosomal locus in S. marcescens for AAC(6')-1 which commonly coexists with plasmid-mediated genes for aminoglycoside-modifying enzymes.
D000123:Acetyltransferases / Q000378:metabolism; D000583:Amikacin / Q000494:pharmacology*; D000617:Aminoglycosides / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002876:Chromosomes, Bacterial; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000032:analysis; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000235:genetics; D007612:Kanamycin / Q000031:analogs & derivatives*; D010957:Plasmids; D012706:Serratia marcescens / Q000187:drug effects* / Q000235:genetics; D013379:Substrate Specificity
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D007612:Kanamycin; D000583:Amikacin; D000123:Acetyltransferases; C019681:aminoglycoside acetyltransferase