Abstract

Susceptibility of 128 strains of bacteria isolated from clinical materials at Kyungpook National University Hospital in 1981 were determined by disc diffusion and plate dilution methods. A total of 128 isolates consisting of 49 Staphylococcus aureus, 29 Serratis marcescens and 50 Escherichia coli were tested. 19 strains of S. aureus were isolated from pus, and 20 strains of S. marcescens and 31 strains E, coli were isolated from urine specimens. Susceptible isolates of S. aureus by disc diffusion method and plate dilution method and plate dilution method were 95.9% and 87.8% to amikacin, 98.0% and 87.8% to cephalothin. 51.0% and 42.9% to chloramphenicol, 53.1% and 49.0% to gentamicin, 14.3% and 57.1% to penicillin G, and 20.4% and 20.4% to tetracycline respectively. Susceptible isolates of S. marcescens were 55.2% and 41.4% to amikacin, 37.9% and 27.6% to gentamicin, 31.0% and 13.4% to tobramycin, 3.4% and 0% to ampicillin, 24.1% and 0% to chloramphenicol. To cephalothin and to tetracycline all of the isolates showed resistance by both methods. Susceptible isolates of E. coli were 96.0% and 100% to amikacin, 87.0% and 78.0% to cephalothin 72.0% and 72.0% to tobramycin, 24.0% and 26.0% to ampicillin, 28.0% and 26.0% to chloramphenicol, 18.0% and 8.0% to tetracycline respectively. Comparison of the results of susceptibility by disc diffusion method and plate dilution method showed a tendency of slightly higher rate of susceptibility by the former method. Minimum inhibitory concentration of amikacin was 1～32㎍/㎖ against E. coli, but in other antibiotics remarkable difference was noted in minimum inhibitory concentrations. Some difference was noted in susceptibility of the same species depending on the source of isolation of organisms.