title: Evidence of plasmid-mediated production of aminoglycoside-modifying enzymes not previously described in Acinetobacter.
abstract: Two blood culture isolates of Acinetobacter calcoaceticus subsp. anitratus (Herellea vaginicola) were recently observed to be unusually resistant to aminoglycosides. Each strain was found to contain aminoglycoside-modifying enzymes which have not been described previously in this species, including 2"-adenylyltransferase, 3"-adenylyltransferase, 3'-phosphotransferase-III, and 3-acetyltransferase. Treatment of one strain (H-S) with novobiocin led to a loss of resistance to multiple antimicrobial agents and a loss of two aminoglycoside-modifying enzymes; agarose gel electrophoresis of lysates of this strain revealed that the loss of resistance markers was associated with the loss of a large-molecular-weight plasmid. Treatment of the second strain (H-D) with novobiocin produced derivative strains with three different resistance patterns. Agarose gel electrophoresis of deoxyribonucleic acid from crude lysates and from cesium chloride-ethidium bromide gradients of this strain showed only a small plasmid (molecular weight, 5 X 10(6)) common to all variants and failed to explain the loss of resistance markers.
mesh_terms: D000150:Acinetobacter / Q000187:drug effects / Q000201:enzymology*; D000617:Aminoglycosides / Q000378:metabolism* / Q000494:pharmacology; D004269:DNA, Bacterial / Q000032:analysis; D004352:Drug Resistance, Microbial; D010957:Plasmids; D013379:Substrate Specificity
chemical_list: D000617:Aminoglycosides; D004269:DNA, Bacterial