Recently the bacterium Escherichia coli (E. coli) has been prominently featured in the news due to sickness caused by E. coli water contamination. Bacterial drinking water contamination may have a detrimental effect on the expansion of the livestock industry. Thus techniques which could trace E. coli water contamination to its source are needed. Genetic fingerprinting is one such technique. The polymerase chain reaction (PCR) is used to amplify fragments of the E. coli DNA. These fragments are visualized on a gel in the form of a series of bands much like a bar code. Each bar code is unique to one particular strain of E. coli. However barcodes from E. coli strains all isolated from one species of animal (pigs or chickens or cows) may be more similar to each other than are barcodes from E. coli which came from different kinds of animals. Thus possible contamination could be traced back to its source. With the support of the MLMMI we isolated and identified 91 E. coli strains from pigs, cattle, and chickens living on Manitoban farms and from humans. Each E. coli strain was fingerprinted using rep-PCR. This is a variation of fingerprinting making use of repeating sequences in the DNA of E. coli to start PCR. The fingerprints were converted into a series of 1 and 0; 1 for the presence of a band and 0 for its absence. This allowed comparison of fingerprints using statistical analysis. We found that the fingerprints of the 91 E. coli strains were quite different from each other. No groups of E. coli fingerprints corresponded to a particular animal. It appears that in Manitoba livestock and in the human population there is a wide variety of E. coli genetic types. We have not yet found genetic types of E. coli specific to any variety of livestock animal. E. coli is ubiquitous in the mammalian intestinal tract and may move from animal to animal and species to species. Further investigation with other methods of determining which animal group a specific E. coli isolate came from is underway.