Role of Shiga-like toxin I in bacterial enteritis: comparison between isogenic Escherichia coli strains induced in rabbits.
OBJECTIVE
Enteroadherent Escherichia coli that produce Shiga-like toxins are important causes of human disease, including enterohemorrhagic E. coli-induced colitis (EHEC). The role of Shiga-like toxins in these illnesses is unclear. The aim of this study was to establish an animal model for human EHEC and to determine the role of Shiga-like toxin I (SLT-I) in this model.


METHODS
E. coli strain RDEC-1 is an enteroadherent rabbit diarrheal pathogen. An isogenic variant of RDEC-1 (termed RDEC-H19A) producing high levels of SLT-I was obtained by infecting RDEC-1 with an SLT-I-converting bacteriophage. The effects of in vivo enteric infection produced in rabbits by RDEC-H19A were compared with those in uninfected and RDEC-1-infected animals.


RESULTS
SLT-I-producing RDEC-H19A induced a severe, noninvasive, enteroadherent infection in rabbits. Clinically, infection with RDEC-H19A was more severe than infection with RDEC-1 and caused more serious histological lesions including vascular changes, edema, and more severe inflammation. Interleukin 1 and platelet-activating factor appear to be important inflammatory mediators to this infection.


CONCLUSIONS
The illness induced by RDEC-H19A in rabbits resembled enterohemorrhagic E. coli-induced colitis of humans. SLT-I is an important virulence factor in the pathogenesis of EHEC.
Sjogren
R
R
Division of Medicine, Walter Reed Army Institute of Research, Washington, D.C.
Neill
R
R
Rachmilewitz
D
D
Fritz
D
D
Newland
J
J
Sharpnack
D
D
Colleton
C
C
Fondacaro
J
J
Gemski
P
P
Boedeker
E
E
D000818:Animals; D001427:Bacterial Toxins / Q000633:toxicity*; D004751:Enteritis / Q000209:etiology; D004760:Enterocolitis / Q000209:etiology* / Q000473:pathology; D004768:Enterotoxins / Q000633:toxicity*; D004926:Escherichia coli / Q000472:pathogenicity*; D006367:HeLa Cells; D006801:Humans; D007375:Interleukin-1 / Q000502:physiology; D008297:Male; D010972:Platelet Activating Factor / Q000502:physiology; D011817:Rabbits; D022622:Shiga Toxin 1
D001427:Bacterial Toxins; D004768:Enterotoxins; D007375:Interleukin-1; D010972:Platelet Activating Factor; D022622:Shiga Toxin 1