Gentamicin-resistant gram-negative bacilli in hospital patients. Part II. In vitro aspects including susceptibility to tobramycin and amikacin.

A study of 259 clinical isolates of gentamicin-resistant Gram-negative bacili (GRNB) has revealed 99,2% crossresistance with tobramycin and 6,9% with amikacin. Resistance to all 3 drugs is transferable in vitro. Simultaneous transfer of resistance to ampicillin, carbenicillin, cephalothin, tetracycline, chloramphenicol, sulphonamides, co-trimoxazole, streptomycin and kanamycin was shown to occur, emphasizing the potential for the selection of aminoglycoside-resistant organisms by the use of many other drugs. All GRNB studied were multiresistant. While amikacin should prove useful for those infections caused by GRNB which require treatment, care should be exercised in its use, to minimize the emergence of large-scale amikacin resistance.