The significance of numbers of coliform bacteria as an indicator of enteric pathogens

Abstract To ascertain whether there is any level of total and fecal coliform densities below which the probability of isolating salmonellae, a pathogenic bacteria, would be negligible, a comparison of coliform data with salmonellae data gathered in stream surveys throughout the United States has been made. Since one of the premises for using coliform as an indicator organism is that it is presumably indicative of the probable presence of pathogenic organisms, any relationship between numbers of coliform and isolation of pathogens would be valuable in determining permissible bacteriological water quality standards. A comparison of Salmonella typhimurium and fecal coliform survival time conducted under laboratory conditions is also presented. A summary of data shows little apparent correlation between levels of total or fecal coliform and the isolation of Salmonella. Some observations are made as to why this may be so, and the implications of using only coliform densities to describe bacteriological acceptability for recreational and fishing uses are discussed.