Microbiological characterization of dactimicin: antibacterial activity towards gram-positive and gram-negative...

Dactimicin is the first aminoglycoside antibiotic of Dactylosporangium origin, consisting of a pseudo-disaccharide and an amino acid. It has also a formimidoyl moiety instead of the deoxystreptamine found in other aminoglycosides. The authors considered the antibacterial activity of dactimicin compared with amikacin, gentamicin and the fortimicins against Gram-positive and Gram-negative bacteria. Dactimicin showed remarkable antibacterial activity against all strains tested: in particular the MIC90 values ranged from 2 mg/l for Citrobacter sp. to 32 mg/l for Proteus sp. Methicillin-resistant staphylococci were poorly susceptible to all aminoglycosides tested, while dactimicin showed good activity against the methicillin-susceptible strains. MBCs and killing curves indicated that this drug is rapidly bactericidal against all strains tested.