Aminoglycoside Antibiotic-Inactivating Enzymes in Actinomycetes Similar to Those Present in Clinical Isolates of Antibiotic-Resistant Bacteria

Various species of Streptomyces possess aminoglycoside-modifying enzymes. Streptomyces kanamyceticus contains an enzyme that acetylates the 6‧-amino group of kanamycin A and B, gentamicin C_1a, and neomycin. Streptomyces spectabilis produces an enzyme that acetylates the 2‧-amino group of the hexose ring of gentamicin C_1a. These enzymes catalyze reactions identical to those catalyzed by enzymes found in gram-negative bacteria containing R(antibiotic resistance)-factors. The discovery of these enzymes suggests the possibility of an evolutionary relationship between the aminoglycosideinactivating enzymes (produced by resistance determinants) in bacteria containing R-factors and similar enzymes found in the actinomycetes.