Key words: Shigella, Bacterial resistance against entibiotics. Distribution of R factors
dihydrostreptomycin(sm), sulfanilamide(sa), kanamycin(km), paromomycin(prm), fradiomycin(frm), ampicillin(apc), cephaloridine (CER), nalidixic acid(na), colistin methansulfonate(cl), gentamicin(gm), furatridin (FT), furazolidon(fz) Ì14 ò Ü ð p ½ ª, Table I. Isolation frequency of the drug-resistant Shigella strains The results based on surveys of 12,453 strains isolated from 1965 to 1973. Abbreviation of drugs: TC,tetracycline; CM,chloramphenicol; SM,streptomycin; SA,sulfanilamide; KM,kanamycin; PRM,paromomycin; FRM, fradiomycin; APC,ampicillin; CER,cephaloridine; NA, nalidixic acid; CL,colistin methansulfonate; GM, gentamicin; FT,furatridine; FZ,furazolidon.
Table 2. Drug-resistance patterns of Shigella strains Results of survey for resistance to TC, CM, SM and SA are shown in the table. Fig. 1 Isolation frequency of antibiotic-resistant Shigella strains
Table 3. Isolation frequency of R factors from Shigella strains Numerator, number of IR' strains; denominator, number of tested strains. Percentage was not computed the number strains was fewer than when of 10.
Table 4. Isolation of Shigella strains in hetero-r state The gene governing SA resistance was located on nontransferable plasmid(r) and r(sa) was cojugally transferred by the presence of R(TC) plasmid4 Fig. 2 Drug resistance patterns of R factors from Shigella strain Fig. 3 Yearly changes of the serotypes of Shigella strains isolated in Japan No. of R factors 911
Table 5. Isolation frequency of R factors from Shigella strains of various serotype Strains tested are the same as those shown in Table 3, Percentage was not compdted when the number of strains was fewer than 10. Table 6. Isolation frequency of APC-, NA-, and KM-resistant strains with reference to 4-drug resistant type Four drugs; TC, CM, SM and SA.
Table 7. Isolation frequency of APC-, NA-, and KM-resistant strains from Shigella strains in relation to resistance to 4 drugs; TC, CM, SM and SA. Table 8. Isolation frequency of R factors possessing APC-, NA-, KM or CER-resistance No, of strains examined was 12,453. Table 9. Resistance patterns of R factors carrying KM or APC resistance R-factor carrying Resistance patterns No. of R factor isolated APC resistance TC.CM.SK.SA.KM.APC 11 TC.CM.SM.SA.APC 116 TC.SM.SA.APC 1 CM.SM.SA.APC 3 SM.SA.APC 1 CM;SA.APC 1 APC 1 KM resistance TC,CM,SM.SA.APC.KM 11 TC.CM-SM.SA.KM 1 CM.SM,SA,KM 5 SM.SA.KM 2 TC.SM,KM 1 KM 4 Results based on surveys of 13k strains with APC resistance and 23 strains with KM resistance. They were isolated from 1971 to 1973.
therapy, 20: 553, 1972. 21) Farrar, W. E., Jr. & Eidson, M.: J. Infect. Dis., 123: 477-484, 1971. 22) Lebek, G.: Ein Experimenteller Beitrag. Zentralbl. Bakteciol. Parasitenk. Abt. I. Orig., 188: 494-505, 1963. 23) Anderson, E.S. & Datta, N.: Lancei., 1: 407-409, 1965. 8) Mitsuhashi, S., et al.: Jap. J. Exp. Med., 31: 47, 1961; 31: 53, 1961. 26) Kabins, S. A. & Cohen, S.: New Eng. J. 9) Davies, B.D. & Mingioli, E. S.: J. Bacteriol., Med., 275: 248-252, 1966. 60: 17-28, 1950. 27) Davies, J. R., Farrant, W.N. & Tomlinson, A. J. H.: J. Hyg.(Camb.)., 66: 471-477, 1968. 28) Gill, F. A. & Hook, E. W.: J. Amer. Med. Chemotherapy, 17: 1956-1963, 1969. Ass., 198: 1267-1269, 1966. 12) Tanaka, T., Na. gai, Y., Hashimoto, H. & 29) Yoshikawa, M.; Nagashima, S. & Matsushima, Mitsuhashi, S.: Japan. J. Microbiol., 13: S.: Japan. J. Microbiol., 15: 425-187-191, 1969. 436, 1971. 13) Tanaka, T., Tsunoda, M. & Mitsuhashi, S.: 30) Tanaka, T., Ikemura, K., Tsunoda, M., Japan. J. Microbiol., 17: 291-295, 1973. 14) Tanaka, T., Kobayashi, A., Ikemura, K., Hashimoto, H. & Mitsuhashi, S.: Japan. J. Microbiol., 18: 343-347, 1974. 32) Iyobe, S., Hasuda, K., Fuse, A. & Mitsuhashi, S.: Antimicrob. Agents. Chemother., 5: 547-552, 1974. Sasagawa, I. & Mitsuhashi, S.: Antimicrob. Agents. Chemother.( Š e ) 31) Odakura, Y., Tanaka, T. & Mitsuhashi, S.: Japan. J. Microbiol., 15: 367-372, 1971. Drug Resistance and Distribution of R factors among Shigella Strains Tokumitsu TANAKA Department of Microbiology, School of Medicine, Gunma University We collected 12,453 Shigella strains isolated in many municipal hospitals from 1965 to 1973 and surveyed their drug resistance. The results are summarized as follows. 1. Drug resistance patterns of Shigella strains are mainly restricted to resistance to TC, CM, SM and SA, and to the combinations thereof. Isolation frequency of strains resistant to KM, NA and APC is much lower than that of strains resistant to the aforementioned four drugs. 2. Isolation frequency of strains resistant to(tc.cm.sm.sa) was the highest, and followed by
those resistant to SA,(CM.SM.SA), and(sm.sa). The strains with other resistance patterns were isolated rarely at less than 1%. 3. Demonstration frequency of R factors was rather low from the strains with single resistance and much higher from those with multiple resistance. The R factors were demonstrated most frequently from the triply resistant strains at a frequency of 86.7%. 4. Isolation frequency of KM-, NA-, or APC-resistant strains was rather low, but the R factors encoding resistance to KM and APC were demonstrated at high frequencies from the strains resistant to the drugs. The R factors possessing NA resistance were never isolated thus far. 5. Resistance patterns of Shigella strains and of their R factors were quite similar to those in Escherichia coli, and different from those in Salmonella, Proteus, and Pseudomonas aeruginosa.