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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #164500
Title: LONG POLAR FIMBRIAE CONTRIBUTE TO COLONIZATION BY ESCHERICHIA COLI O157:H7 IN VIVO

Author
item JORDAN, DIANNA - IOWA STATE UNIVERSITY
item CORNICK, NANCY - IOWA STATE UNIVERSITY
item TORRES, ALFREDO - UNIVERSITY OF MARYLAND
item Nystrom, Evelyn
item KAPER, JAMES - UNIVERSITY OF MARYLAND
item MOON, HARLEY - IOWA STATE UNIVERSITY

Submitted to: Infection and Immunity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/12/2004
Publication Date: 10/20/2004
Citation: Jordan, D.M., Cornick, N., Torres, A.G., Dean-Nystrom, E.A., Kaper, J.B., Moon, H.W. 2004. Long polar fimbriae contribute to colonization by Escherichia coli O157:H7 in vivo. Infection and Immunity. 72(10):6168-6171.

Interpretive Summary: Escherichia coli O157:H7 and other enterohemorrhagic E. coli (EHEC) are foodborne pathogens that cause severe diarrhea and sometimes kidney failure and death in humans. Ruminants are an important source of EHEC O157:H7 that cause infections in humans. Pigs are also susceptible to EHEC infections and neonatal pigs are used as models for studies the mechanisms of EHEC O157:H7 infection and disease. The objective of this study was to determine if bacterial adhesins called long polar fimbriae (LP fimbriae) help EHEC O157:H7 bacteria to stick to the intestinal surface and establish infections. We infected sheep and pigs with one of two isogenic LP fimbriae-negative mutants EHEC O157:H7 or with LP fimbriae-positive EHEC O157:H7 in sheep and pigs and evaluated the number of EHEC bacteria in their feces at 3 to 60 days after inoculation. We also compared the intestinal lesions that these strains caused in neonatal pigs. We showed that LP fimbriae helped EHEC colonize and damage the intestines of sheep and pig. However, the absence of LP fimbriae did not prevent EHEC infections or disease. These results suggest that LP fimbriae are only one of the multiple factors involved in EHEC infections. LP fimbriae do not appear to be a suitable target for EHEC interventions.

Technical Abstract: Long polar fimbriae, encoded by the lpf operon, enhance the severity of murine typhoid caused by Salmonella enterica serovar Typhimurium. There are two loci (lpfA1 and lpfA2) in the Escherichia coli O157:H7 genome bearing homology to lpf genes in S. Typhimurium. In this study, the contribution of long polar fimbriae to intestinal colonization by E. coli O157:H7 was evaluated in sheep, conventional pigs and gnotobiotic piglets. Two isogenic mutants of E. coli O157:H7 strain 86-24, a single lpfA1 mutant strain, CVD468, and a lpfA1 lpfA2 double mutant strain, AGT201, were evaluated. Three groups of sheep were inoculated with either the parent strain of E. coli O157:H7 or one of its two isogenic mutant strains. One group of conventional pigs was dually inoculated with both the parent and the double mutant strains. Feces from the sheep and pigs were sampled over eight weeks for fecal shedding of the inoculum strains. The parent E. coli O157:H7 was recovered in significantly higher numbers than the AGT210 strain from the sheep and pigs only early (less than or equal to 2 weeks PI) in the two month study. Tissues from the gnotobiotic pigs infected with AGT210 had a significant reduction in attachment and effacement lesions when compared to the parent strain and the single mutant strain infected tissues. These studies are consistent with the hypothesis that long polar fimbriae contribute to the colonization and persistence by E. coli O157:H7 in swine and sheep.