Development of amikacin resistance in bacterial isolates in Slovakia (1990-1992).

In-vitro susceptibility of 7301 clinical isolates of Gram-negative bacilli, originating from hospitals at and around Bratislava, to amikacin was evaluated during the years 1990-1992. In 1990 amikacin resistance represented 4.1%, in 1991 it increased to 7.3% and in 1992 a slight decline to 6.4% was observed. In Slovakia during the last decade amikacin usage increased by 300%. The predominating mechanism of resistance was production of modifying enzymes, mainly in Enterobacteriaceae. The unique enzyme inactivating amikacin was AAC(6')-I. This enzyme was found in all isolates in combination either with APH(2''), characteristics up to now only for staphylococci, or with AAC(3) enzyme.