Dept. of Immunology (면역학); Dept. of Microbiology (미생물학)
Microdilution; 0.3% yeast extract
School of Medicine
대한미생물학회 The Korean Society For Microblology, Vol.23(2) : 195-205, 1988
Microdilution broth system has been increasingly applied for quantitative antimicrobial susceptibility in recent years, and known as a convenient, inexpensive, and reliable method. This study was carried out to evaluate the applicability of microdilution susceptibility test on strains of staphylococci, Escherichia coli’ Shigella，Klebsiella, Serraiia and Pseudomonas aeruginosa, etc. isolated from various pathological specimens, and the results were evaluated in correlation with the reference agar dilution method by the agreement of minimal inhibitory concentrations(MICs) obtained by two melthods.
Mueller-Hinton broth with 0.3% dextrose and 0.004% phenol red(MHDP) was used to test the susceptibility of E. coli, Shigella, Klebsiella, and Serratia, etc. Oxidation-Fermentation basal medium was filtered out the agar and added with dextrose(l%) for P. aeruginosa, and MHDP with yeast extract(0.3%) was used for staphylococci.
Comparing the results obtained by microdilution broth system and agar dilution method, the agreement of MICs of both methods were highly satisfactory. The agreement of MICs of drugs tested were more than 90% in staphylococci except penicillin(70.7%) and ampicillin (78.3%)；in E. coli except streptomycin(Sm, 85.1%), sulfisomidine(Su, 78.9%), and cefaman-dole(77.7%)；in Shigella except Sm(87.1%), trimethoprim(87.1%), and nalidixic acid(83.9%) ； in Klebsiella except tetracycline(87.5%), Su(62.5%)，and kanamycin(87.5%). The results of all drugs tested in P. aeruginosa showed more than 90% of agreement, but Serratia, Proteus, Ciirobacter，and Enterobacter, agreement of 7 among 16 drugs were over 90% and 8 drugs Over 8196. MICs of staphylococci against methicillin(Mt) were found to be in agreement with the reference agar dilution method in 96.2% of strains.
Therefore, the microdilution broth system was fairly satisfactory for antimicrobial susceptibility test, and it is reasonable to suggest that the addition of 0.3% yeast extract in the MHDP will be a suitable media to test the susceptibility of staphylococci to Mt.