Shigella strains associated with infantile diarrhea in the Kaohsiung area.

In 1969 and 1974, 375 Shigella strains were isolated in the Kaohsiung area, and their serotypes and in vitro susceptibility to antimicorbial agents were studied. In 1969, 249 (16.2%) strains were isolated from 1,476 specimens collected from infantile and young children dirrheal cases, whereas 126 strains (11.6%) were isolated from 1,086 specimens in 1969. The isolation rates were higher in May (21.2%), October (20.8%), April (20.6%), August (19.7), November (18.8%) and January (18.5%), than in other months (10.2%-18.0%). Higher incidences of shigellosis appeared in May (22.3%) and April (17.9%) than in the other months during 1974. Shigella sonnei and Shigella flexneri type 2 were most predominant and there was a tendency of increase in number for the former in 1974. From the colicine typing of S. sonnei, it was found that type 8 (40.6%), type 6 (23.4%), and type 12 (17.2%) were the commonly occurring strains associated with the infantile diarrheal disease in the Kaohsiung area. Susceptibility study showed that the resistant rates of S. flexneri to chlroamphenicol (85.5%), streptomycin (81.9%), and tetracycline (61.3%) were much higher than to ampicillin (16.1%), nalidixic acid (14.6%), colistin (4.2%), kanamycin (4.2%), gentamicin (2.8%), cephaloridine (2.4%), and frazolidone (0%). Resistant rates of S. sonnei to 10 antimicrobial agents were as follows: chloramphenicol, 85.9%; tetracycline, 70.2%; streptomycin, 69.9%; nalidixic acid, 16.4%; ampicillin, 13.3%; colistin, 6.3%; kanamycin, 3.9%; gentamicin, 2.5%; cephaloridine, 0%; and frazolidone, 0%.