Elevated-temperature technique for the isolation of Salmonella from streams

With a modified Moore swab for sampling bacteria, Salmonella organisms were recovered consistently from surface waters when the enrichment broths of SBG-sulfa and tetrathionate and Brilliant Green Agar plates were incubated at 41.5 C. When an equal portion of the same swab sample was incubated at 37.0 C, no salmonellae were detected. By use of the elevated-temperature technique, salmonellae were recovered from stream sites having relatively low total coliform densities of 2,200 per 100 ml and fecal coliform densities of 220 per 100 ml. These pathogens were isolated in water sampled as far as 73 river miles and 4 days time of travel downstream from the source of pollution under an ice cover that averaged 2.5 ft (76.2 cm) in thickness.