Shiga toxin 2 overexpression in Escherichia coli O157:H7 strains associated with severe human disease

• DOI: 10.1016/j.micpath.2011.07.009
• Publication Date: 2011-08-16T19:16:54Z
• Authors: Mahesh Neupane; Galeb S. Abu-Ali; Avishek Mitra; David W. Lacher; Shannon D. Manning; James T. Riordan
• Keywords: 0301 basic medicine; Kidney Disease; Immunology; Gene Expression; Escherichia coli O157; Microbiology; Polymorphism, Single Nucleotide; Shiga Toxin 2; Disease Outbreaks; Vaccine Related; 03 medical and health sciences; Rare Diseases; Spinacia oleracea; Factors relating to the physical environment; Genetics; Cluster Analysis; Humans; Polymorphism; Aetiology; Escherichia coli Infections; Virulence; Single Nucleotide; United States; 3. Good health; Molecular Typing; Emerging Infectious Diseases; Infectious Diseases; Medical Microbiology; Hemolytic-Uremic Syndrome; Immunization; Digestive Diseases; Infection; Biotechnology

Variation in disease severity among Escherichia coli O157:H7 infections may result from differential expression of Shiga toxin 2 (Stx2). Eleven strains belonging to four prominent phylogenetic clades, including clade 8 strains representative of the 2006 U.S. spinach outbreak, were examined for stx2 expression by real-time PCR and western blot analysis. Clade 8 strains were shown to overexpress stx2 basally, and following induction with ciprofloxacin when compared to strains from clades 1-3. Differences in stx2 expression generally correlated with Stx2 protein levels. Single-nucleotide polymorphisms identified in regions upstream of stx2AB in clade 8 strains were largely absent in non-clade 8 strains. This study concludes that stx2 overexpression is common to strains from clade 8 associated with hemolytic uremic syndrome, and describes SNPs which may affect stx2 expression and which could be useful in the genetic differentiation of highly-virulent strains.