Types and Sanitary Significance of Fecal Streptococci Isolated from Feces, Sewage, and Water

Abstract

Over 5,000 strains of fecal streptococci were isolated by membrane filter techniques from fresh and salt waters, sewage and feces of man and various animals. These were classified by physical and biochemical tests to determine the kind, distribution of species and biotypes present. The IMViC types of coli-forms in the same samples were also determined. The same species and biotypes of enterococci isolated from feces were also isolated from sewage and the various polluted waters. Streptococcus faecalis was found to be mainly of human origin while other biotypes were largely distributed in the feces of lower animals and in man. Raffinose fermentation was characteristic of animal strains, especially bovine, but not of human. From 92 to 100% of the strains of coliforms isolated from human and various animal feces were Escherichia coli types. In sewage and contaminated water, the E. coli types dropped to about 50% of the total coiiforms isolated. Known numbers of selected enterococci were placed in sterilzed dialyzing bags and immersed in fresh and salt water streams to determine the per cent survival after one to 7 or more days. Numbers decreased by 25 to 75% in 24 hrs; only a small number remained viable after 7 days. Storage of water samples in the laboratory at 8[degree]C showed little change in numbers of both fecal streptococci and coiiforms for periods up to 2 days. There was a definite decrease in numbers of these organisms in samples stored at 260C after a one-day storage period. Membrane filter tests for fecal streptococci are more practical, efficient and accurate than coliform tests for evaluating the sanitary quality of almost all types of waters.