Aminoglycoside-modifying enzymes in high-level streptomycin and gentamicinresistant Enterococcus spp. in Spain

Aminoglycoside resistance was evaluated in 690 enterococcus strains isolate d from different clinical sources originating from patients at the Universi ty Clinic Hospital of Zaragoza (Spain). The enterococci obtained from clini cally significant samples (blood, urine, or exudates) showed more high-leve l resistance to gentamicin and streptomycin (65 and 42%, respectively) than those isolated from faecal samples (49 and 23%, respectively). Aminoglycos ide-modifying enzymes (AME) from 119 of these high-level gentamicin and str eptomycin resistant enterococcus strains were studied. The most frequent AM Es found were APH(3') and AAC(6')-APH(2 "). More than one enzyme was detect ed in 71% of the strains (four different enzymes in 5% of the strains). Thr ee Enterococcus faecalis strains had ANT(4')(4 ") enzymatic activity. Diffe rent enzymatic expressions of the bifunctional enzyme AAC(6')-APH(2 ") were demonstrated in strains in which the complete aac(6')-aph(2 ") gene was de tected by PCR and hybridization: (i) AAC(6') + APH(2 ") activity; (ii) AAC( 6') only; (iii) APH(2 ") only; and (iv) no activity of AAC(6') or APH(2 "). (C) 2000 Elsevier Science B.V. and International Society of Chemotherapy. All rights reserved.