Resistance surveillance programs and the incidence of gram-negative bacillary resistance to amikacin from 1967 to 1985

Data relating to amikacin resistance among gram-negative bacilli were obtained by means of a review of published literature and resistance surveillance studies. Data from the first several years of amikacin use are difficult to interpret because the 10-μg disk used for Kirby-Bauer susceptibility testing resulted in apparent greater resistance than the present 30-μg disk. A large United States susceptibility surveillance program that monitors antibiotic use has shown a trend since 1977 of greater susceptibility of Serratia species and greater resistance among Pseudomonas aeruginosa for all the aminoglycosides. Pseudomonas resistance to amikacin has shown the smallest increase of any aminoglycoside. Several hospitals (Strong Memorial Hospital, University of Maryland Cancer Center, and Minneapolis Veterans Administration Medical Center) have reported either no significant change or a decrease in resistance to amikacin when it was the most frequently used aminoglycoside. In a large, 14-center, prospective study, high-level use of amikacin resulted in a significant decrease in resistance to gentamicin and tobramycin (p <0.01) and a marginal increase (p <0.05) in amikacin resistance. Significantly increased amikacin resistance has been reported from two institutions, neither of which used amikacin as the predominant aminoglycoside. Overall, the high-level use of amikacin in large multi-center surveillance programs for as long as five years has not resulted in a significant increase in amikacin resistance rates at any of the individual institutions surveyed.