Division of Infectious Diseases, Department of Medicine, the University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6021, USA. ebbing@mail.med.upenn.edu
Of 49 long-term care facility residents, 21 (43%) were colonized with 2 or more distinct strains of Escherichia coli. There were no significant risk factors for colonization with multiple strains of E. coli. These results suggest that future efforts to efficiently identify the diversity of colonizing strains will be challenging.