Sensitivity of gram-negative bacteria to six aminoglycoside antibiotics.

An in vitro study of the susceptibility of 201 newly isolated strains of gramnegative bacteria to six aminoglycoside antibiotics (kanamycin, amikacin, gentamicin, tobramycin, sisomicin and netilmicin) was performed by the twofold dilution method in fluid medium. Both the minimal inhibitory concentration and the minimal bacteridical concentration were determined. Overall, tobramycin seemed the most effective of the drugs studied. Netilmicin, the new derivative from sisomicin, compared favourably with the other drugs tested, but may, on theoretical grounds, offer the additional advantage of retained efficacy in the face of developing bacterial resistance. Not unexpectedly, amikacin appeared to be the most promising of the drugs studied in its action against Pseudomonas aeruginosa. Amikacin and netilmicin appeared to be the most effective of this group of antibiotics against Klebsiella species.