On the Epidemic of Bacillary Dysentery in Tochigi Prefecture from 1951 to 1953, with Special Reference to the Sensitivity of Bacilli to Medicaments

Abstract

The sensitivity tests to sulfathiazol, chloramphenicol, Streptomycin and Terramycin were performed on 1, 444 strains of dysentery bacilli, isolated in Tochigi Prefecture from 1951 to 1953.
Resistent to sulfathiazol were 296 strains, including la, 1b, 2a and 2b, out of 368 strains isolated in 1951. No strain of Shigella sonnei exhibited a significant resistance.
The sensitivity to chloramphenicol was examined on 355 strains isolated in 1951. The growth of bacteria was observed in 7 strains (1.9%) only at a concentration of chloramphenicol below 0.5λ/cc, while 31 strains (8.6%), including 20 strains of Shigella sonnei, were not inhibited by 5.0λ/cc of chloramphenicol. The remaining 317 strains exhibited growth at a chloramphenicol concentration of 1.0λ/cc to 2.5λ/cc. In 1952, 520 strains were isolated, of which 35 strains (6.7%) grew only at a chloramphenicol concentration below 0.5λ/cc, and 96 strains (18%), including 56 strains of Shigella sonnei, were not inhibited even by 5.0λ/cc. The other 389 strains (74.8%) grew at a chloramphenicol concentration of 1.0λ/cc-2.5λ/cc. Out of 569 strains, isolated in 1953, 71 (12.4%) showed growth at a chloramphenicol concentration below 0.78λ/cc, and 78 (13.9%), including 70 strains of Shigella sonnei, were not inhibited by 6.25λ/cc. The other 419 (72, 8%) grew in the range of 1.56λ/cc-3.12λ/cc.
The sensitivity to Streptomycin was examined on 821 strains. The number of strains, of which growth was only permitted at a concentration of Streptomycin up to 12.5λ/cc, was 4 (4.4%) in 1951, 28 (10.4%) in 1952 and 34 (6.1%) in 1953. Streptomycin, even in a concentration from 50λ/cc to 100λ/cc, could not suppress the growth of 27 strains (30%) in 1951, 79 strains (29.4%) in 1952 and 116 strains (20.9%) in 1953. The remaining 623 strains grew at a concentration from 12.5λ/cc to 50λ/cc.
Resistent to Terramycin up to a concentration of 0.78λ/cc were 15 (2.7%) out of 542 strains, isolated in 1953. The growth of other 59 strains (10.8%), including 56 strains of Shigella sonnei, could not be inhibited even by 6.25λ/cc of Terramycin. The other 468 strains grew at a Terramycin concentration from 1.56λ/cc to 3.12λ/cc. Lower sensitivity to Terramycin was confirmed with 197 strains of Shigella belonging to the B-group, and with 17 strains belonging to the D-group, than with standard strains.
The above-mentioned results did not indicate a gradually elevated resistance of isolated dysentery bacilli to chloramphenicol, Streptomycin and Terramycin from 1951 to 1953.