Frequency of Resistance to Aminog lycoside Antibiotics in Staphy lococcus aureus Isolated from Tertiary Hospitals / 감염

ABSTRACT

BACKGROUND: Staphylococcus aureus is one of the most important pathogens, causing severe morbidity and fatal infections. To date rapid evolution of antibiotic resistance in S. aureus, including recent emergence of vancomycin-resistant S. aureus (VRSA), has been a serious concern and an obstacle to the effective treatment. The purpose of this study is to update the resistance patterns against aminoglycoside antibiotics which play an important role in the therapy of serious staphylococcal infections. METHODS: Clinical isolates were collected from 8 university-affiliated hospitals during the period of June 1999 to January 2001. Susceptibility tests against 9 antibiotics were performed by disk diffusion method. Minimum inhibitory concentrations (MICs) of arbekacin against non-susceptible strains were determined by microbroth dilution method RESULTS: Among total 682 isolates exclusive of consecutive ones from the same patients, 199 (29%) were from pus, 152 (22%) from respiratory specimens, 137 (20%) from blood, 38 (6%) from urine. Of 682 isolates, 588 (87%) isolates were resistant to at least one of the aminoglycosides tested. Overall prevalence of MRSA was 64% (439/682), and resistance rates of MRSA were summarized as follows; kanamycin (KM) 98%, tobramycin (TOB) 98%, gentamicin (GM) 95%, amikacin (AMK) 90%, neomycin (NEO) 63%, streptomycin (SM) 31%, netilmicin (NET) 18%, arbekacin (ABK) 13%. MRSA isolates were resistant to multiple aminoglycosides, and 88% of them were resistant to all four aminoglycosides of KM, TOB, GM, and AMK. MICs of ABK against 58 non-susceptible strains ranged from 2 to 128 microgram/mL. CONCLUSION: More than 90% of MRSA isolates were resistant against kanamycin, tobramycin, gentamicin, and amikacin. Moreover, most of MRSA isolates were multi-drug resistant to all these four aminoglycosides. Resistance rates against arbekacin and netilmicin were less than 20%. Arbekacin was the most susceptible antibiotic of the aminoglycosides tested.