The in vitro antibacterial activity of nine aminoglycosides and spectinomycin on clinical isolates of common Gram-negative bacteria

Abstract

The antibacterial activity of nine aminoglycosides (streptomycin, neomycin, kana-mycin, amikacin, gentamicin, sissomicin, verdamicin, tobramycin and dibekacin) and spectinomycin was compared. Gentamicin, sissomicin, verdamicin, tobramycin and amikacin were approximately equally effective against Enterobacteriaceae (93 to 96% of 351 strains sensitive) and were more effective than the other agents. Tobramycin was the most effective agent against (94% of 34 strains sensitive) followed by dibekacin and sissomicin (88% sensitive) and amikacin, gentamicin and verdamicin (76 to 79% sensitive). Pseudomonads (other than Ps. aeruginosa) were divided into two groups on the basis of their sensitivity to gentamicin. The gentamicin-sensitive strains were also generally sensitive to sissomicin, verdamicin, tobramycin and amikacin (97 to 100% of 38 strains sensitive) and most were sensitive to all agents except streptomycin and spectinomycin. In contrast the 42 gentamicin-resistant strains were generally resistant to all the agents, although 33% were sensitive to kanamycin and 19 to 21% to neomycin or amikacin. Gentamicin, verdamicin, kanamycin, amikacin and neomycin were most effective against Acinetobacter spp. (100% of 20 strains sensitive). All 17 strains of Haemophilus influenzae were sensitive to all the agents except dibekacin. Spectinomycin, sissomicin and verdamicin were the most effective agents against Neisseria gonorrhoeae (100% of 41 strains sensitive) followed by kanamycin and gentamicin (95 to 97% sensitive).