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One hundred and eighty six shigella strains were isolated in Seoul area during a period from 1972 to 1979 and they were classified by means of biochemical and serological test. These strains originated from patients who had clinically been diagnosed as bacillary dysentery and other gastrointestinal complaints. Sensitivities to 12 kinds of antimicrobial agents were carried out by means of agar plate,dilution technique in Mueller-Hinton agar. A control plate free of drug was inoculated with each culture tested. Readings were made after 24 hours at 37°C and were determined by the criteria of complete inhibition of growth of test organism. A strain was regarded as resistant if its growth was inhibited in the presence of 100mcg/ml of tetracycline (Tc), chloramphenicol (Cp) , streptomycin (Sm) , sulfa-nilamide (Sa), and ampicillin (Ap), 25mcg/ml of kanamycin (Km), cephaloridine (Cep), furazolidone(Fz), nitrofurantoin(Nf), and nalidixic acid(Na) and 6.25mcg ,/ml of gentamycin(Gm). Of total strains, 138 belong to Shigella(Sh) flexneri, 2 to Sh.boydii, and 46 to Sh. sonnei. The susceptibilities of organisms to 12 drugs - examined were found to be the highest to Na and the lowest to Ap and to Sa. In other hand the susceptibilities to Tc,Cp,Sm, and Sa in Sh. flexneri strains were shown to be higher than in Sh. sonnei strains. Fz and Nf, however, the susceptibilities of Sh.sonnei strains were higher than that of Sh.flexneri strains. Shigella species showed a more significant resistance to Tc(52. 1 5,1,), Cp(58. 1 %), Sm(41. 3), and Sa(46. 1 %) and showed a resistance to Nf (36.9 % ), Gm (22. 2 % ), Ap (20. 6%), Cep (15.9%), Na(2.1%), Fz(1.4%), Km(0.7%), Fm (0.7%) in order. It was also found that there is a marked difference between Sh. flexneri and Sh. sonnei to Sm, Sa, Ap and Cep. The multiple resistant strians of TcCpSm and TcCp pattern were the most predominant and shown remarkable difference in the frequency of these resistance among Sh. flexneri and Sh. sonnei strains. The strains which shown to be resistant to Tc Cp Sm Ap or Cep were also resistant to Nf, Gm, and Cep.
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