Human Infections with Non-O157 STEC, Switzerland | CDC EID

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Volume 17, Number 2–February 2011
Research
Human Infections with Non-O157 Shiga Toxin–producing Escherichia coli, Switzerland, 2000–2009
Ursula Käppeli, Herbert Hächler, Nicole Giezendanner, Lothar Beutin, and Roger Stephan
Author affiliations: University of Zurich, Zurich, Switzerland (U. Käppeli, H. Hächler, N. Giezendanner, R. Stephan); and Federal Institute for Risk Assessment, Berlin, Germany (L. Beutin)
Suggested citation for this article

Abstract
We characterized 97 non-O157 Shiga toxin (stx)–producing Escherichia coli strains isolated from human patients during 2000–2009 from the national reference laboratory in Switzerland. These strains belonged to 40 O:H serotypes; 4 serotypes (O26:H11/H–, O103:H2, O121:H19, and O145:H28/H–) accounted for 46.4% of the strains. Nonbloody diarrhea was reported by 23.2% of the patients, bloody diarrhea by 56.8%. Hemolytic uremic syndrome developed in 40.0% of patients; serotype O26:H11/H– was most often associated with this syndrome. Forty-five (46.4%) strains carried stx2 genes only, 36 strains (37.1%) carried stx1, and 16 (16.5%) strains carried stx1 and stx2. Genes encoding enterohemolysin and intimin were detected in 75.3% and 70.1% of the strains, respectively. Resistance to >1 antimicrobial agent was present in 25 isolates. High genetic diversity within strains indicates that non-O157 stx–producing E. coli infections in Switzerland most often occurred as single cases.
Shiga toxin (stx)–producing Escherichia coli (STEC) is among the most common causes of food-borne diseases (1). This organism is responsible for several human gastrointestinal illnesses, including nonbloody or bloody diarrhea. Especially in children, these diseases may be affected by neurologic and renal complications, including hemolytic uremic syndrome (HUS). Most outbreaks and sporadic cases of bloody diarrhea and HUS have been attributed to strains of STEC serotype O157:H7. However, in Europe and recently in the United States, the role of non-O157 STEC strains (e.g., O26:H11/H–, O91:H21/H–, O103:H2, O111:H–, O113:H21, O121:H19, O128:H2/H–, and O145:H28/H–) as causes of HUS, bloody diarrhea, and other gastrointestinal illnesses is being increasingly recognized (1).

The common feature and main virulence factor of STEC is production of stx1 or stx2 proteins. Human virulent STEC strains often may also contain other virulence factors such as intimin (eae), a protein essential for the intimate attachment and the formation of attaching and effacing lesions on gastrointestinal epithelial cells, and E. coli hemolysin (ehxA) (2).

Little data are available for clinical non-O157 STEC infections in humans, including those in Switzerland, a country with a small but disproportionately high population of travelers. Therefore, we characterized all non-O157 STEC strains collected by the Swiss National Centre for Enteropathogenic Bacteria (Zurich, Switzerland) during 2000–2009, characterized these strains according to clinical and anamnestic data, and compared these results with data from other countries in Europe and the United States.

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Human Infections with Non-O157 STEC, Switzerland | CDC EID



Suggested Citation for this Article
Käppeli U, Hächler H, Giezendanner N, Beutin L, Stephan R. Human infections with non-O157 Shiga toxin–producing Escherichia coli, Switzerland, 2000–2009. Emerg Infect Dis [serial on the Internet]. 2011 Feb [date cited].
http://www.cdc.gov/EID/content/17/2/180.htm


DOI: 10.3201/eid1702.100909


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Roger Stephan, Institute for Food Safety and Hygiene, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 272, CH-8057 Zurich, Switzerland; email: stephanr@fsafety.uzh.ch