Submitted to: Infection and Immunity
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/7/2004
Publication Date: 2/20/2005
Citation: Jordan, D.M., Sperandio, V., Kaper, J.B., Nystrom, E.A., Moon, H.W. 2005. Colonization of gnotobiotic piglets by a luxS mutant strain of Escherichia coli O157:H7. Infection and Immunity. 73(2):1214-1216. 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 important sources of EHEC O157:H7 that cause infections in humans. Neonatal pigs are used as models for studies the mechanisms of EHEC O157:H7 infection and disease. Some enteric bacterial pathogens use a bacterial cell-to-cell signaling mechanism called quorum sensing for recognition of the host environment. In E. coli O157:H7, the LuxS enzyme contributes to the production of a signaling compound called autoinducer-3, which is involved in the quorum sensing regulation of some enterohemorrhagic E. coli virulence genes. The objective of this study was to determine if mutations in the luxS gene impair the ability of E. coli O157:H7 to colonize gnotobiotic piglets. Gnotobiotic piglets were inoculated with E. coli O157:H7, its luxS- derivative, or nonpathogenic E. coli and evaluated for clinical signs and intestinal colonization, based on attaching and effacing intestinal lesions. There were no differences in the clinical signs or types of lesions in the two groups of E. coli O157:H7-inoculated pigs. The pigs inoculated with the luxS mutant had less frequent A/E lesions in the spiral colon compared pigs inoculated with the parent strain, but there were no differences in the frequency of lesions in the cecum or ileum. These results suggest that quorum sensing is only one of the many factors EHEC use to colonize the intestinal tract. Other bacterial and host factors which can compensate for the loss of the quorum sensing signal in the luxS mutant must be considered when evaluating the role that quorum sensing plays in EHEC colonization.
Technical Abstract: Gnotobiotic piglets inoculated with E. coli O157:H7, its luxS- derivative, or nonpathogenic E. coli were evaluated for attaching and effacing lesions. Although no differences in clinical symptoms were seen between the parent and the luxS mutant, the luxS-mutant-inoculated pigs had reduced frequency of attaching and effacing lesions in the spiral colon when compared with parent-strain-inoculated pigs.