Distribution of group D streptococci in rivers and streams

A study was undertaken to determine sources of bacteriological contamination of rivers as well as the ecology of faecal streptococci in natural and contaminated waters. Media used to characterize and speciate group D streptococci were also evaluated using isolates from the water and sediment. Due to the low concentrations of faecal coliforms (FC) and faecal streptococci (FS) in river water samples, the FC/FS ratio was shown to be of little value in determining sources of contamination. High concentrations of FC and FS from sediment samples gave more credible FC/FS ratios. The actual distribution of group D streptococcal species in rivers and streams was also shown. High concentrations of all division II species (S. faecium, S. faecium var. casseliflavus, and S. faecium var. durans) were found in the water and sediment samples, with S. faecium var. durans comprising 50% of the total number of isolates. Low concentrations of division I group D streptococci (S. faecalis and varieties) were found, while only one isolation of division III group D streptococci (S. bovis and S. equinus) was made.