Ribotyping to determine the host origin of Escherichia coli isolates in different water samples

One problem in evaluating water quality is obtaining fecal coliforms in a w ater sample but not knowing the host origin of these bacteria. One solution to this problem may be to isolate the bacteria and observe their ribosomal DNA fingerprints (ribotyping). This may allow isolates to be associated wi th a particular host. We obtained 35 isolates of Escherichia coli, a fecal coliform, from cow manure in a pasture, and compared these isolates to 40 i solates of E. coli from a stream draining that pasture and 44 isolates from a geographically separated wooded stream remote from domesticated animals and human habitation. The isolates were ribotyped with a Qualicon RiboPrint er(TM) with the restriction enzyme EcoRI. Among the 119 isolates, the RiboP rinter(TM) system identified eight different ribotypes. The wooded stream a nd the cow manure each contained six ribotypes, while the pasture stream co ntained all eight. In the wooded stream, 29 of the 44 isolates (66%) were R ibotypes #6 and #8, while in the cow manure, 19 isolates (54%) were Ribotyp e #4. Our results suggest that either a limited variation in ribotypes of E . coli exists among the two streams and the cow manure, or a more discrimin atory ribotyping system is needed.