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Prevalence, virulence profiles, and clinical significance of Shiga toxin-negative variants of enterohemorrhagic Escherichia coli O157 infection in humans.
Clin Infect Dis. 2007 Jul 01; 45(1):39-45.CI

Abstract

BACKGROUND

Escherichia coli O157, of the H7 clone, exists in humans and in the environment as Shiga toxin (Stx)-positive and Stx-negative variants. Stx production by infecting organisms is considered to be a critical requirement for the development of hemolytic uremic syndrome (HUS), which occurs in approximately 15% of E. coli O157-infected patients. It is unknown if loss of the stx gene during the early stage of an enterohemorrhagic E. coli infection prevents HUS, or if absence of the stx gene from E. coli O157 reduces or ablates virulence.

METHODS

We determined the frequency of stx-positive and stx-negative E. coli O157 isolates in stool samples obtained from patients who experienced sporadic cases of diarrhea or HUS, as well as the frequency in samples obtained during outbreaks, and investigated the clinical course of the disease.

RESULTS

Among E. coli O157 isolates obtained from samples related to sporadic cases of diarrhea, stx-negative strains accounted for 4%. The proportion of stx-negative strains was significantly higher among sorbitol-fermenting, nonmotile E. coli O157 isolates (12.7%) than among non-sorbitol-fermenting E. coli O157:H7 or nonmotile isolates (0.8%; P<.001). stx-Negative sorbitol-fermenting E. coli O157 isolates were also observed in samples related to 3 HUS outbreaks and 1 outbreak of diarrhea caused by sorbitol-fermenting, nonmotile enterohemorrhagic E. coli O157; additionally, they were the only pathogens that were isolated in 2 other outbreaks of diarrhea without HUS.

CONCLUSIONS

Strains of stx-negative E. coli O157 isolated from stool samples of patients are either inherently stx-negative strains that cause mostly uncomplicated diarrhea, or strains that descended from enterohemorrhagic E. coli O157 by the loss of the stx gene during infection; the latter strains may still cause severe disease.

Authors+Show Affiliations

National Consulting Laboratory on Hemolytic Uremic Syndrome, Institute for Hygiene, University of Münster, Münster, Germany.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

17554698

Citation

Friedrich, Alexander W., et al. "Prevalence, Virulence Profiles, and Clinical Significance of Shiga Toxin-negative Variants of Enterohemorrhagic Escherichia Coli O157 Infection in Humans." Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America, vol. 45, no. 1, 2007, pp. 39-45.
Friedrich AW, Zhang W, Bielaszewska M, et al. Prevalence, virulence profiles, and clinical significance of Shiga toxin-negative variants of enterohemorrhagic Escherichia coli O157 infection in humans. Clin Infect Dis. 2007;45(1):39-45.
Friedrich, A. W., Zhang, W., Bielaszewska, M., Mellmann, A., Köck, R., Fruth, A., Tschäpe, H., & Karch, H. (2007). Prevalence, virulence profiles, and clinical significance of Shiga toxin-negative variants of enterohemorrhagic Escherichia coli O157 infection in humans. Clinical Infectious Diseases : an Official Publication of the Infectious Diseases Society of America, 45(1), 39-45.
Friedrich AW, et al. Prevalence, Virulence Profiles, and Clinical Significance of Shiga Toxin-negative Variants of Enterohemorrhagic Escherichia Coli O157 Infection in Humans. Clin Infect Dis. 2007 Jul 1;45(1):39-45. PubMed PMID: 17554698.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Prevalence, virulence profiles, and clinical significance of Shiga toxin-negative variants of enterohemorrhagic Escherichia coli O157 infection in humans. AU - Friedrich,Alexander W, AU - Zhang,Wenlan, AU - Bielaszewska,Martina, AU - Mellmann,Alexander, AU - Köck,Robin, AU - Fruth,Angelika, AU - Tschäpe,Helmut, AU - Karch,Helge, Y1 - 2007/05/21/ PY - 2006/12/22/received PY - 2007/03/06/accepted PY - 2007/6/8/pubmed PY - 2007/7/20/medline PY - 2007/6/8/entrez SP - 39 EP - 45 JF - Clinical infectious diseases : an official publication of the Infectious Diseases Society of America JO - Clin Infect Dis VL - 45 IS - 1 N2 - BACKGROUND: Escherichia coli O157, of the H7 clone, exists in humans and in the environment as Shiga toxin (Stx)-positive and Stx-negative variants. Stx production by infecting organisms is considered to be a critical requirement for the development of hemolytic uremic syndrome (HUS), which occurs in approximately 15% of E. coli O157-infected patients. It is unknown if loss of the stx gene during the early stage of an enterohemorrhagic E. coli infection prevents HUS, or if absence of the stx gene from E. coli O157 reduces or ablates virulence. METHODS: We determined the frequency of stx-positive and stx-negative E. coli O157 isolates in stool samples obtained from patients who experienced sporadic cases of diarrhea or HUS, as well as the frequency in samples obtained during outbreaks, and investigated the clinical course of the disease. RESULTS: Among E. coli O157 isolates obtained from samples related to sporadic cases of diarrhea, stx-negative strains accounted for 4%. The proportion of stx-negative strains was significantly higher among sorbitol-fermenting, nonmotile E. coli O157 isolates (12.7%) than among non-sorbitol-fermenting E. coli O157:H7 or nonmotile isolates (0.8%; P<.001). stx-Negative sorbitol-fermenting E. coli O157 isolates were also observed in samples related to 3 HUS outbreaks and 1 outbreak of diarrhea caused by sorbitol-fermenting, nonmotile enterohemorrhagic E. coli O157; additionally, they were the only pathogens that were isolated in 2 other outbreaks of diarrhea without HUS. CONCLUSIONS: Strains of stx-negative E. coli O157 isolated from stool samples of patients are either inherently stx-negative strains that cause mostly uncomplicated diarrhea, or strains that descended from enterohemorrhagic E. coli O157 by the loss of the stx gene during infection; the latter strains may still cause severe disease. SN - 1537-6591 UR - https://www.unboundmedicine.com/medline/citation/17554698/Prevalence_virulence_profiles_and_clinical_significance_of_Shiga_toxin_negative_variants_of_enterohemorrhagic_Escherichia_coli_O157_infection_in_humans_ L2 - https://academic.oup.com/cid/article-lookup/doi/10.1086/518573 DB - PRIME DP - Unbound Medicine ER -