Abstract
During 5 yr at Walter Reed Army Hospital, the frequency of aminoglycoside resistance among clinical bacterial isolates increased from < 1% in 1976 to 13% of all isolates in later years. This resistance was seen among frequently isolated species of gram-negative bacilli isolated from patients throughout the hospital and from all anatomical sites, including blood. The incidence of gentamicin and amikacin resistance rose with increased administration of these antibiotics; the incidence of tobramycin resistance increased despite its minimal usage. From 1977-1978 and from 1979-1980, there was a decrease in the conjugal transmissibility of resistance to gentamicin and tobramycin. There was no detectable transmissible amikacin resistance. Evidently, high priority must be given to strategies that limit the emergence and dissemination of organisms resistant to these important antibiotics.