Detection and characterization of the fimbrial sfp cluster in enterohemorrhagic Escherichia coli O165:H25/NM isolates from humans and cattle.
The sfp cluster, encoding Sfp fimbriae and located in the large plasmid of sorbitol-fermenting (SF) enterohemorrhagic Escherichia coli (EHEC) O157 (pSFO157), has been considered a unique characteristic of this organism. We discovered and then characterized the sfp cluster in EHEC O165:H25/NM (nonmotile) isolates of human and bovine origin. All seven strains investigated harbored a complete sfp cluster (carrying sfpA, sfpH, sfpC, sfpD, sfpJ, sfpF, and sfpG) of 6,838 bp with >99% nucleotide sequence homology to the sfp cluster of SF EHEC O157:NM. The sfp cluster in EHEC O165:H25/NM strains was located in an approximately 80-kb (six strains) or approximately 120-kb (one strain) plasmid which differed in structure, virulence genes, and sfp flanks from pSFO157. All O165:H25/NM strains belonged to the same multilocus sequence type (ST119) and were only distantly phylogenetically related to SF EHEC O157:NM (ST11). The highly conserved sfp cluster in different clonal backgrounds suggests that this segment was acquired independently by EHEC O165:H25 and SF EHEC O157:NM. Its presence in an additional EHEC serotype extends the diagnostic utility of PCR targeting sfpA as an easy and efficient approach to seek EHEC in patients' stools. The reasons for the convergence of pathogenic EHEC strains on a suite of virulence loci remain unknown.
Bielaszewska
Martina
M
Institut für Hygiene, Universität Münster, Robert-Koch-Str. 41, 48149 Münster, Germany. mbiela@uni-muenster.de
Prager
Rita
R
Vandivinit
Liz
L
Müsken
Anne
A
Mellmann
Alexander
A
Holt
Nicholas J
NJ
Tarr
Phillip I
PI
Karch
Helge
H
Zhang
Wenlan
W
D000818:Animals; D015373:Bacterial Typing Techniques; D002417:Cattle; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D054324:Enterohemorrhagic Escherichia coli / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000235:genetics; D010861:Fimbriae, Bacterial / Q000235:genetics*; D023061:Gene Order; D005838:Genotype; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid
D004269:DNA, Bacterial