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Enhanced virulence of the Escherichia coli O157:H7 spinach-associated outbreak strain in two animal models is associated with higher levels of Stx2 production after induction with ciprofloxacin.
Infect Immun. 2014 Dec; 82(12):4968-77.II

Abstract

Shiga toxin (Stx)-producing Escherichia coli (STEC) causes hemorrhagic colitis and the hemolytic-uremic syndrome (HUS). STEC strains may produce Stx1a and/or Stx2a or variants of either toxin. A 2006 spinach-associated outbreak of STEC O157:H7 resulted in higher hospitalization and HUS rates than previous STEC outbreaks. The spinach isolate, strain K3995, contains both stx2a and stx2c. We hypothesized that the enhanced virulence of K3995 reflects the combination of stx2 alleles (carried on lysogenic phages) and/or the amount of Stx2 made by that strain. We compared the virulence of K3995 to those of other O157:H7 isolates and an isogenic Stx2 mutant in rabbits and mice. We also measured the relative levels of Stx2 produced from those strains with or without induction of the stx-carrying phage. Some rabbits infected with K3995 exhibited intestinal pathology and succumbed to infection, while none of those infected with O157:H7 strain 2812 (Stx1a(+) Stx2a(+)) died or showed pathological signs. Rabbits infected with the isogenic Stx2a mutant K3995 stx2a::cat were not colonized as well as those infected with K3995 and exhibited no signs of disease. In the streptomycin-treated mouse model, more animals infected with K3995 died than did those infected with O157:H7 strain 86-24 (Stx2a(+)). Additionally, K3995 produced higher levels of total Stx2 and toxin phage DNA in cultures after phage induction than did 86-24. Our results demonstrate the greater virulence of K3995 compared to other O157:H7 strains in rabbits and mice. We conclude that this enhanced virulence is linked to higher levels of Stx2 expression as a consequence of increased phage induction.

Authors+Show Affiliations

Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.Program of Comparative Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA Departments of Pathology, Epidemiology, and Preventive Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.Program of Comparative Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA.Program of Comparative Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA Departments of Pathology, Epidemiology, and Preventive Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA Department of Medicine (Infectious Diseases), University of Maryland, School of Medicine, Baltimore, Maryland, USA.Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA alison.obrien@usuhs.edu.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

25225244

Citation

Zangari, T, et al. "Enhanced Virulence of the Escherichia Coli O157:H7 Spinach-associated Outbreak Strain in Two Animal Models Is Associated With Higher Levels of Stx2 Production After Induction With Ciprofloxacin." Infection and Immunity, vol. 82, no. 12, 2014, pp. 4968-77.
Zangari T, Melton-Celsa AR, Panda A, et al. Enhanced virulence of the Escherichia coli O157:H7 spinach-associated outbreak strain in two animal models is associated with higher levels of Stx2 production after induction with ciprofloxacin. Infect Immun. 2014;82(12):4968-77.
Zangari, T., Melton-Celsa, A. R., Panda, A., Smith, M. A., Tatarov, I., De Tolla, L., & O'Brien, A. D. (2014). Enhanced virulence of the Escherichia coli O157:H7 spinach-associated outbreak strain in two animal models is associated with higher levels of Stx2 production after induction with ciprofloxacin. Infection and Immunity, 82(12), 4968-77. https://doi.org/10.1128/IAI.02361-14
Zangari T, et al. Enhanced Virulence of the Escherichia Coli O157:H7 Spinach-associated Outbreak Strain in Two Animal Models Is Associated With Higher Levels of Stx2 Production After Induction With Ciprofloxacin. Infect Immun. 2014;82(12):4968-77. PubMed PMID: 25225244.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Enhanced virulence of the Escherichia coli O157:H7 spinach-associated outbreak strain in two animal models is associated with higher levels of Stx2 production after induction with ciprofloxacin. AU - Zangari,T, AU - Melton-Celsa,A R, AU - Panda,A, AU - Smith,M A, AU - Tatarov,I, AU - De Tolla,L, AU - O'Brien,A D, Y1 - 2014/09/15/ PY - 2014/9/17/entrez PY - 2014/9/17/pubmed PY - 2015/1/13/medline SP - 4968 EP - 77 JF - Infection and immunity JO - Infect Immun VL - 82 IS - 12 N2 - Shiga toxin (Stx)-producing Escherichia coli (STEC) causes hemorrhagic colitis and the hemolytic-uremic syndrome (HUS). STEC strains may produce Stx1a and/or Stx2a or variants of either toxin. A 2006 spinach-associated outbreak of STEC O157:H7 resulted in higher hospitalization and HUS rates than previous STEC outbreaks. The spinach isolate, strain K3995, contains both stx2a and stx2c. We hypothesized that the enhanced virulence of K3995 reflects the combination of stx2 alleles (carried on lysogenic phages) and/or the amount of Stx2 made by that strain. We compared the virulence of K3995 to those of other O157:H7 isolates and an isogenic Stx2 mutant in rabbits and mice. We also measured the relative levels of Stx2 produced from those strains with or without induction of the stx-carrying phage. Some rabbits infected with K3995 exhibited intestinal pathology and succumbed to infection, while none of those infected with O157:H7 strain 2812 (Stx1a(+) Stx2a(+)) died or showed pathological signs. Rabbits infected with the isogenic Stx2a mutant K3995 stx2a::cat were not colonized as well as those infected with K3995 and exhibited no signs of disease. In the streptomycin-treated mouse model, more animals infected with K3995 died than did those infected with O157:H7 strain 86-24 (Stx2a(+)). Additionally, K3995 produced higher levels of total Stx2 and toxin phage DNA in cultures after phage induction than did 86-24. Our results demonstrate the greater virulence of K3995 compared to other O157:H7 strains in rabbits and mice. We conclude that this enhanced virulence is linked to higher levels of Stx2 expression as a consequence of increased phage induction. SN - 1098-5522 UR - https://www.unboundmedicine.com/medline/citation/25225244/Enhanced_virulence_of_the_Escherichia_coli_O157:H7_spinach_associated_outbreak_strain_in_two_animal_models_is_associated_with_higher_levels_of_Stx2_production_after_induction_with_ciprofloxacin_ L2 - http://iai.asm.org/cgi/pmidlookup?view=long&pmid=25225244 DB - PRIME DP - Unbound Medicine ER -