Outbreak of Shiga toxin-producing E. coli O104 (STEC O104:H4)

Edited by Dr Ihab Suliman

What is Escherichia coli

• Escherichia coli (abbreviated as E. coli) are a large and diverse group of bacteria. Although most strains of E. coli are harmless, others can make you sick. Some kinds of E. coli can cause diarrhea, while others cause urinary tract infections, respiratory illness and pneumonia, and other illnesses.

• A large outbreak of Shiga toxin-producing Escherichia coli O104:H4 (STEC O104:H4) infections ongoing in Germany.

• The responsible strain shares virulence characteristics with enteroaggregative E. coli (EAEC).

• As of May 31, 2011, case counts confirmed by Germany’s Robert Koch Institute include 470 patients with hemolytic uremic syndrome (HUS) – a type of kidney failure that is associated with E. coli or STEC infections – and nine deaths.

Disease background information

• Shiga toxin-producing E. coli (STEC) is a group of pathogenic Escherichia coli strains capable of producing Shiga toxins, with the potential to cause severe enteric and systemic disease in humans.

• The full serotype is usually defined by determining both O and H antigens.

• There are around 200 different E. coli O serotypes producing Shiga toxin, of which over 100 have been associated with human disease.

• Two major Shiga toxin types (Stx1 and Stx2) have been associated with strains causing human disease. While the serotype O157:H7 is considered as clinically the most important, it is estimated that up to 50% of STEC infections are caused by non-O157 serotypes.

• Haemolytic uremic syndrome (HUS) is considered as the most common cause of acute renal failure in European children. Even if the clinical presentation of non-O157 STEC infections may vary, they can be as virulent as O157:H7 infections.

Transmission of STEC infection mainly

occurs through contaminated food or water

• Transmission of STEC infection mainly occurs through contaminated food or water and contact with animals.

• Person-to-person transmission is also possible among close contacts (families, childcare centres, nursing homes, etc).

• A wide variety of food has previously been implicated in outbreaks as suspected sources, including raw (unpasteurised) raw milk and cheese, undercooked beef, a variety of fresh produce (e.g. sprouts, spinach, lettuce), unpasteurised apple cider,

The infective dose is very low.

• The infective dose is very low.

The incubation period ranges from three to eight days.

• The incubation period ranges from three to eight days.

• Many of these illnesses are in persons who report recent travel to Germany, but reside elsewhere.

• In the United States, three suspected cases of STEC O104:H4 infections have been identified in persons recently traveled to Hamburg, Germany.

Investigation of the Outbreak

• At this time, a specific food has not been confirmed as the source of the infections. Travelers to Germany should be aware that the German public health authorities have recommended against eating raw lettuce, tomatoes, or cucumbers, particularly in the northern states of Germany (Hamburg, Bremen, Lower Saxony, and Schleswig Holstein).

Clinical Features/Signs and Symptoms

• Symptoms of STEC infection include severe stomach cramps, diarrhea (which is often bloody), and vomiting. If there is fever, it usually is not very high.

• Most people get better within 5–7 days, but some patients go on to develop HUS—usually about a week after the diarrhea starts. Symptoms of HUS include decreased frequency of urination, feeling very tired, and losing pink color to skin and membranes due to anemia.

What is the best treatment for STEC infection

• Non-specific supportive therapy, including hydration, is important.

• Antibiotics should not be used to treat this infection.

• There is no evidence that treatment with antibiotics is helpful, and taking antibiotics may increase the risk of HUS. Antidiarrheal agents like Imodium® may also increase that risk.

How can STEC infections be prevented

• WASH YOUR HANDS thoroughly after using the bathroom or changing diapers and before preparing or eating food. WASH YOUR HANDS after contact with animals or their environments (at farms, petting zoos, fairs, even your own backyard).

• COOK meats thoroughly. Ground beef and meat that has been needle-tenderized should be cooked to a temperature of at least 160°F/70˚C. It’s best to use a thermometer, as color is not a very reliable indicator of “doneness.”

• AVOID raw milk, unpasteurized dairy products, and unpasteurized juices (like fresh apple cider).

• AVOID swallowing water when swimming or playing in lakes, ponds, streams, swimming pools, and backyard “kiddie” pools.

• PREVENT cross contamination in food preparation areas by thoroughly washing hands, counters, cutting boards, and utensils after they touch raw meat.