STEC
Shigatoxin-producing Escherichia coli
Profile
Bacteria of the species Escherichia (E.) coli are part of the normal intestinal flora in humans and animals. If they acquire the ability to produce a specific toxin, shiga toxin, they are called shiga toxin-producing E. coli (STEC) after this toxin. STEC are sensitive to heat but survive in frozen foods and in acidic environments. The terms verotoxin-forming E. coli (VTEC) and enterohemorrhagic E. coli (EHEC) are used as synonyms for STEC. These pathogenic types can also cause fatal diseases.
Infection route
Transmission of the bacteria occurs mainly through the consumption of contaminated food, such as raw beef mince, Mettwurst, salami, raw milk, but also plant foods cultivated on fields fertilized with cattle manure and consumed raw, as well as industrially produced sprouts. Of importance are transmissions after contact with ruminants (petting zoos), if no appropriate cleaning of the hands (hand washing with soap) is carried out afterwards, as well as human-to-human chains of infection, which is to be observed especially in community facilities (kindergartens, old people's homes, etc.). It is assumed that 50-100 STEC germs are sufficient to cause the disease in healthy people.
Symptomatology
The disease usually begins with watery diarrhea, which often becomes bloody after a few days and may be accompanied by severe nausea, vomiting and abdominal pain. The disease is predominantly self-limiting and lasts on average eight to ten days. In about 5-10% of cases, especially in young children, a characteristic secondary disease, the life-threatening hemolytic uremic syndrome (HUS), may develop days after the onset of diarrhea. The toxin binds to special receptors on the cell walls and damages blood capillaries; this can lead to kidney failure (lack of urine formation), anemia, reduced platelet count, skin hemorrhages and neurological changes.
Animals: calf diarrhea may occasionally be (co-)caused by STEC. STEC can also sporadically cause diarrhea in lambs, goats, dogs, and cats. In pigs, a subtype of STEC causes the so-called edema disease.
Prevention
Since ruminants and wild ruminants are considered to be the reservoir of these bacteria, strict adherence to hygiene regulations, e.g. washing hands after animal contact, is of great importance. Persons who have contracted STEC infections must not be employed in the commercial production, handling or marketing of foodstuffs until a decision by the health authority indicates that they are no longer likely to spread the disease. This also applies mutatis mutandis to employees in kitchens of restaurants, canteens, hospitals, infant and children's homes and in communal catering areas.
Human
In 2025, the rise in reported STEC cases continued: 984 cases were recorded in the EMS, corresponding to 10.7 cases per 100,000 population. The number of reported HUS cases stood at 12, remaining similar to previous years (EMS data as at 3 March 2025). Each year, molecular typing enables the identification of several clusters of human cases; however, confirmed foodborne outbreaks remain rare despite extensive investigations. In most cases, the source of infection remains unknown.
Isolates from 559 patients were typed. The seven most common serotypes currently account for around half of all typed isolates; previously, there were four serotypes.
Food-borne outbreaks of illness
In 2025, a foodborne outbreak caused by STEC was reported in Austria, affecting two people.
Food
In 2025, a total of 1,165 food samples were tested for STEC: 773 samples of animal origin, 390 samples of non-animal origin and 2 samples of food for special dietary purposes. A total of 22 samples tested positive. Most of the positive results were found in fresh meat and cereal/flour products; the highest detection rate was once again observed in game.
No STEC was detected in processed foods (n=28). All 146 samples of fruit, vegetables, seeds, juices, spices, etc. were negative. Of 149 samples from the categories of baked goods and cereals and flours, five were positive. No STEC was detected in 13 raw milk samples and 118 cheese samples; one sample was positive among dairy products other than cheese (including butter, n=88). Of 175 samples of fresh meat, nine were positive; no STEC was detected in fresh beef (n=68). The highest prevalence was found in game, with 8 out of 64 samples (12.5 per cent).
The serotype distribution showed no clustering of any particular type. The most frequently identified type was STEC O27:H30, found six times in roe deer/red deer meat; all other types were detected only once or twice.
Human Medicine
Based on their antigen structure, E. coli, and thus also STEC, can be classified into different serogroups (O-like surface antigens "without puff"). The most important STEC serogroup worldwide is O157. Other frequently isolated serogroups are O26, O91, O103, O111, and O145. More and more serogroups could be identified in association with human STEC diseases.
In addition, there are two types of shigatoxins, Stx1 and Stx2. The shiga toxin (stx) genes can be further subdivided into subtypes (stx1a to stx1c and stx2a to stx2i). Severe disease, especially bloody diarrhea and complications such as HUS, are mainly caused by stx2-positive STEC strains.
Diagnostics
Diagnosis is made after clinical suspicion at the National Reference Center for Escherichia coli, including verotoxin-producing E. coli , by detection of a verotoxin gene or cultural culturing of the germs, by detection of verotoxin in stool, or (for HUS only) by detection of specific antibodies in blood:
- Detection of enteroinvasive E. coli (EIEC), enteropathogenic E . coli (EPEC), enterotoxic E. coli (ETEC), enteroaggregative E. coli (EAggEC), and STEC in human stool specimens.
- Isolation and cultural detection of STEC from human stool, food, and environmental samples using selective nutrient media, immunomagnetic separation, slide agglutination, and PCR
- Confirmation and typing of submitted isolates using biochemical and molecular biology methods
- Serotyping
- Fine typing of STEC: typing of shigatoxin genes (PCR), subtyping of shigatoxin genes and typing of other virulence genes (whole genome sequencing)
- Identification of epidemiological correlations of different isolates using whole genome sequencing data
- Detection of specific antibodies in HUS in human serum
- Keeping a master collection of all human, veterinary, feed and food isolates
- Clarification of sources of infection and transmission routes in the context of outbreak investigations
- Consultation on questions of diagnostics, compulsory reporting, epidemiology, food safety, prevention and preventive measures.
Veterinary Medicine
STEC strains that express F18ab fimbriae as specific virulence factors in addition to Stx2e (shiga toxin 2e) appear as pathogens of edema disease (colienterotoxemia).
After weaning of piglets, excessive STEC multiplication in the small intestine may be favored by profound changes in the physiological conditions of the intestine. Stx2e leads to swelling in the tissues (edema) due to vascular damage, typically in the head area especially on the eyelids and on the bridge of the nose and also in the nervous tissue, which can also lead to central nervous phenomena (disturbance in the coordination of muscle movements, paralysis). Treatment of clinically ill animals is often no longer successful. Great importance is attached to metaphylaxis, in the course of which all animals of the affected group are treated non-specifically (e.g. feed deprivation, abundant water supply, possibly oral or parenteral chemotherapy). For prevention, herd-specific vaccines can be administered.
Contact
Institut für veterinärmedizinische Untersuchungen Mödling
- vetmed.moedling@ages.at
- +43 50 555 38112
-
Robert Koch-Gasse 17
2340 Mödling
Last updated: 06.08.2026
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