GENTAMICIN RESISTANCE IN STAPHYLOCOCCUS AUREUS ISOLATED IN JAPAN

PART 3: MECHANISMS OF GENTAMICIN RESISTANCE IN STAPHYLOCOCCUS AUREUS

Abstract

Two transductant strains, MS 353 (pTU 053) and MS 353 (pTU 068), derived from Staphylococcus aureus resistant to gentamicin and other aminoglycosides have been examined for antibiotic modifying enzymes. From the analysis of substrate profiles and inactivated products of sisomicin and amikacin, it was found that MS 353 (pTU 053) strain is containing three enzymes mediating aminoglycoside resistance, 6'-N-acetyltransferase, 3'-phosphotransferase and 2''-phosphotransferase. Also, two enzymes mediating gentamicin resistance, 6'-N-acetyltransferase and 2'-phosphotransferase, were contained in an extract from MS 353 (pTU 068) strain. The optimal pH of acetyltransferase and phosphotransferase activities for sisomicin was near pH 6. 5. The enzymatic phosphorylation of sisomicin by a partially purified enzyme solution from MS 353 (pTU 053) strain occured at a higher rate than that of amikacin.