The survival of Shigella in sewage. I. An effect of sewage and fecal suspensions on Shigella flexneri.

Leiguarda, Peso, and Kempny (1948) reported that no Shigella were isolated during their river water studies in Argentina, although 67 per cent of the samples showed Salmonella. Gispen and Gan (1950) also reported the frequent isolation of Salmonella from river water in Indonesia, but Shigella were not recovered. During a five-year study of irrigation water in Colorado, the present authors likewise failed to isolate Shigella despite the frequent recovery of Salmonella (Dunlop, Twedt and Wang, 1952). The isolation of Shigella organisms from stool specimens also has not been satisfactory. Kligler, Oleinik, and Czazkes (1943) stated that the primary reason for this failure of isolation of Shigella from cases of dysentery appeared to be the age of the stool. Stools cultured shortly after they were voided gave more positives than when culture was delayed. These authors suggested that the presence of Shigella bacteriophage was probably responsible for the rapid death of dysentery bacteria in stools. As Shigella organisms are associated frequently with man's exereta, the danger of consuming raw fruits and vegetables irrigated with sewage-polluted water is recognized. A study, therefore, has been undertaken to investigate the survival of Shigella in sewage and sewage-contaminated irrigation water, and to explore the methods used for isolation of these organisms.