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Infection and Immunity, August 2005, p. 4766-4776, Vol. 73, No. 8
0019-9567/05/$08.00+0     doi:10.1128/IAI.73.8.4766-4776.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Pathoadaptive Mutation That Mediates Adherence of Shiga Toxin-Producing Escherichia coli O111

Alfredo G. Torres,1,2* Roberto C. Vazquez-Juarez,3 Christopher B. Tutt,1 and J. Gerardo Garcia-Gallegos1

Department of Microbiology and Immunology,1 Department of Pathology and Sealy Center for Vaccine Development,University of Texas Medical Branch, Galveston, Texas 77555-1070,2 Departamento de Patología Marina, Centro de Investigaciones Biológicas del Noroeste, La Paz 23000, México3

Received 11 February 2005/ Returned for modification 24 March 2005/ Accepted 4 April 2005

The adherence of pathogenic Escherichia coli strains to intestinal epithelium is essential for initiation of infection. The cad operon encodes the lysine decarboxylase (LDC) system responsible for metabolizing lysine, and this operon has been proposed as an antivirulence mechanism in enteroinvasive E. coli and Shigella flexneri and as a factor mediating E. coli O157:H7 adherence. We sought to determine whether the LDC activity was present in a phylogenetically characterized collection of diarrheagenic E. coli (DEC) strains and to establish whether its expression was associated with their adherence to tissue culture cells. LDC activity was found in most of the pathogenic E. coli strains tested and was absent from Shiga toxin-producing E. coli (STEC) O111 strains (DEC pathotype 8). Analysis of the cad region in these O111 strains indicates that the operon has been rearranged and some of the genes are either missing or disrupted. A similar rearrangement was found in an E. coli O111:H8 strain recently isolated from an outbreak in Texas. Complementation of the LDC-negative strains with the cad operon in trans restored the LDC activity and resulted in a reduction in adherence to tissue culture cells. Initial analysis of the protein profiles on the surface of the O111 strains indicates that the LDC activity has an effect on the expression of the adhesin intimin. Cadaverine had a slight effect on LDC-negative strain adhesion but none on intimin expression. Our data suggest that this pathoadaptive mutation is an important mechanism to control functions potentially implicated in the pathogenesis of these organisms.

* Corresponding author. Mailing address: Department of Microbiology and Immunology and Department of Pathology and Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX 77555-1070. Phone: (409) 747-0189. Fax: (409) 747- 6869. E-mail: altorres{at}utmb.edu.

Editor: J. T. Barbieri

Infection and Immunity, August 2005, p. 4766-4776, Vol. 73, No. 8
0019-9567/05/$08.00+0     doi:10.1128/IAI.73.8.4766-4776.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Vazquez-Juarez, R. C., Kuriakose, J. A., Rasko, D. A., Ritchie, J. M., Kendall, M. M., Slater, T. M., Sinha, M., Luxon, B. A., Popov, V. L., Waldor, M. K., Sperandio, V., Torres, A. G. (2008). CadA Negatively Regulates Escherichia coli O157:H7 Adherence and Intestinal Colonization. Infect. Immun. 76: 5072-5081 [Abstract] [Full Text]  


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