Development of strain-specific PCR reactions for the detection of the probiotic Escherichia coli strain Nissle 1917 in fecal samples

PCR was used to establish a specific detection system for the non-pathogenic Escherichia coli strain Nissle 1917 (DSM6601), which is used as a probiotic drug against intestinal disorders and diseases. Five PCR assays have been developed which are based on the chromosomally encoded major fimbrial subunit genes fimA (type 1 fimbriae) and focA (F1C fimbriae), and the two small cryptic plasmids pMUT1 and pMUT2. The assays were validated by testing a collection of 354 different pathogenic and non-pathogenic E. coli strains from various origins, including E. coli K-12, fecal and environmental as well as pathogenic extraintestinal and intestinal E. coli strains. The most specific results were obtained with primers based on DNA sequences from plasmid pMUT2. The plasmid-based PCR assays described can be used to detect E. coli strain Nissle 1917 in feces from patients without prior cultivation. (C) 2002 Editions scientifiques et medicales Elsevier SAS. All rights reserved.