In vitro activity of dactimicin and other aminoglycosides against bacteria producing aminoglycoside-modifying enzymes
Felmingham, D.; Jones, K.
Drugs under Experimental and Clinical Research 15(3): 133-136
1989
ISSN/ISBN: 0378-6501 PMID: 2752913 Document Number: 338734
Dactimicin is a new pseudo-disaccharide aminoglycoside, orginally isolated from cultures of Dactylosporangium matsuzakienzae sp. nov., which is chemically related to astromicin. In this study the in vitro activity of dactimicin has been determined against strains of bacteria producing characterized amino-glycoside-modifying enzymes and has been compared with that of gentamicin, tobramycin, netilmicin and amikacin. Minimum inhibitory concentrations were determined using an agar incorporation technique in Mueller-Hinton agar with an inoculum of approximately 104 cfu. Dactimicin was resistant to inactivation by a number of different acetyltransferases (AAC), produced by species of the Enterobacteriaceae, most of which inactivated gentamicin, tobramycin and netilmicin. The exception was an AAC(3')-I produced by an isolate of Escherichia coli, which inactivated gentamicin and dactimicin but not tobramycin, netilmicin and amikacin. Dactimicin was inactivated by the adenyltransferases (AAD) AAD(2") and AAD(9), produced by Pseudomonas aeruginosa, but not by an AAD(4')(4"), produced by a strain of Staphylococcus aureus, nor by an AAD(2') produced by a strain of E. coli. Dactimicin was inactivated by a combination of a phosphotransferase (APH) APH(2") and an AAC(6') produced by strains of S. aureus. The results suggest that dactimicin may retain useful antibacterial activity against may gentamicin-resistant strains of bacteria belonging to the Enterobacteriaceae and some gentamicin-resistant strains of S. aureus.