BB-K8 is a new semisynthetic aminoglycoside antibiotic that has an extremely broad spectrum of antimicrobial activity which is due, at least in part, to the compound's high degree of resistance to aminoglycoside-inactivating enzymes. The new derivative inhibited 99.7% of 308 clinical isolates of
Enterobacteriaceae, 100% of 97
Staphylococcus aureus strains, and 94.5% of 110
Pseudomonas sp. in
in vitro tests at concentrations achievable in serum following administration of safe doses to humans. Of 23 strains of
Pseudomonas sp. found resistant to gentamicin, 17 were susceptible to BB-K8 indicating an absence of complete cross-resistance between these antibiotics. BB-K8's bactericidal potential, as well as its response to changes in inoculum size and variations in medium constituents, were similar to those of kanamycin and gentamicin. As has been reported for gentamicin, combinations of BB-K8 with carbenicillin give a high incidence of synergistic responses against
Pseudomonas strains. BB-K8 was well absorbed by mice when administered by the intramuscular route and was less toxic than kanamycin. In experimental infections of mice, BB-K8 was as active as kanamycin in infections caused by kanamycinsensitive bacteria. In addition, it was highly efficacious in infections produced by kanamycin- and/or gentamicin-resistant organisms.
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