Haemolytic and uremic syndrome

The haemolytic and uremic syndrome is a medical affection potentially serious assigning mainly the children and characterized by the appearance of a malfunction of the kidney and a destruction of red globules (Hématie S) and plates.

More rarely, other problems can occur during this Syndrome. They are important digestive attacks (perforation colic, rectal Prolapsus, acute intestinal Invagination), of Pancréatite, Myocardite and neurological disorders .

The multiple attack of all these bodies is related so that this disease touches the whole of the small vessels of the organization by a Toxine produced by a bacterium. (It is the thrombotic Microangiopathie.)

Another syndrome of it is close is found rather in the adult, the Purpura thrombotic thrombocytopenic. In this case, the diarrhea is classically not present.

Causes

The haemolytic and uremic syndrome is generally dependant on named bacteria Shigatoxines Escherichia coli (or STEC, i.e. E. coli producing Vérotoxines), it often acts of the sub-type Escherichia coli O157: H7 . This bacterium is related with the other Escherichia coli which exists naturally in our digestive tract and do not cause in general a disease except the infantile gastro-enteritises (GEI) and sometimes of the urinary infections.

Other bacteria can more rarely be responsible for this disease like shigelles and the Pneumocoque S. Finally a SHU can be caused by Médicament S.

First phase: an attack of the digestive tract

The bacterium in question is introduced by the patient, it multiplies in the digestive tract, generally to the level of the Côlon and adheres to the cells which paper the digestive tract. The bacteria invade the mucous membrane and start a reaction of the defense system of the organization responsible for the symptoms. Thus 3 days after the contamination there is simple a Diarrhée which becomes then bloody. It is noticed that the temperature sometimes high at the beginning, disappears then. There is a “hemorrhagic Colite”. The diarrhea is present in 90% of the cases.

The bacteria produce then a toxin in great quantity and, by complex mechanisms, transfer it in blood. This toxin is conveyed by blood by a type of white globules which one calls polynuclear the neutrophiles. They disperse toxin in the organization which will attack the cells of the walls of the vessels (called endothéliales). At this point in time the symptoms generalized of the disease occur.

In fact the stage of the hemorrhagic colitis is probably related to the action of toxin on the vessels of the digestive tract than has an invasion of the mucous membrane. One speaks besides about entéro-hemorrhagic Escherichia coli in not of entéro-invasive Escherichia coli.

Second phase: a generalized attack

The malfunction of the kidney

The kidney filters the blood of the organization to eliminate waste and to control salt and water from them. It is thus very vascularized and reaches precociously. The toxin reaches the cells of the vessels but also the cells renal it even. If the kidney brutally ceases functioning, one speaks about acute Impaired renal function leading to the accumulation of toxins, water and salt, provocant edema S, arterial Hypertension, a acute edema of the lung. The badly filtering kidney, the quantity of urine decreases strongly or completely. One speaks then about oligo - anurie or Anurie.

To evaluate the function of filtration of the kidney one supervises in blood the concentration of two molecules which are waste of the metabolism-the Urée - or muscles it Créatinine. For a certain threshold of concentration, it is necessary to replace what the kidney in dialyzing did the children time that the repair of the small vessels is carried out.

In a small number of case there can be after-effects with a kidney which functions but insufficiently. One speaks about chronic Impaired renal function. It is irreversible. In other cases it can appear years later a more moderate attack of the kidney with an escape of proteins (Protéinurie) and a arterial Hypertension. A monitoring of the children after the cure is necessary.

Reduction in the plates

The destruction of the cells papering the wall of the vessels starts a complex mechanism intended to clog the brêches via the plates. It are bound at the places where the cells of the walls were destroyed. The number of plate in blood falls by as much. If their number becomes too weak, they cannot ensure minimal repairs of small any more or large vessels. Phenomena of bleeding under the skin can occur in the form of Hématome S, of Purpura. It should however be said that in spite of the significant drops of the plates, the Hémorragie S are in fact rather rare in this disease.

Reduction in the red globules

The cluster of the plates on the wall of the small vessels makes that this one is not smooth any more and the red globules carried in the blood flood to some extent are knocked against these asperities and are destroyed or deformed. They do not have any more their round form and are called Schizocytes. This fall of the red globules being related to their destruction and not on a bleeding or a manufacturing defect of the red globules, one speaks about haemolytic Anémie. This anemia, if it is deep, involves a lack of oxygen for the bodies and requires a blood Transfusion.

Other bodies

As the disease reaches all the small vessels of other bodies can be reached. Thus it can exist neurological signs (Convulsion S, behavioral problems, a Coma, a Aphasie, headaches, etc), signs of attack of the liver, pancreas, heart. In general these attacks are rarer, and appear only in forms described as severe.

Treatment

Currently one can only treat described dysfunctions Ci above:

to control the contribution of the Water and the Rock salt,
Dialysis R,
to transfuse red globules or plates.

The defense system of the organization will destroy the bacteria gradually but will slowly eliminate the toxin which will have had time to make major damage.

Currently it is considered that a treatment Antibiotique is not used for nothing since, when the infection is diagnosed, the toxin is already produced. That is even likely to support the SHU, because by destroying the bacterium one releases even more toxins. The antidiarrhéiques ones are also contra-indicated because they decrease natural elimination by the saddles of the bacterium and toxins.

The antidouleurs “Opiated S” (of which for example: Efferalgan Codeine, Topalgic, Codoliprane, Codenfan) can be also harmful since it slow down the transit and thus the elimination of the bacterium. One should not either use Anti-inflammatoire not stéroïdien (for example: the Aspirine or the Ibuprofène) as antidoulor or cause a drop in the temperature: they can worsen the dysfunction of the kidneys and support the bleedings.

The tests of new treatments did not show a frank effectiveness yet.

How to avoid this medical affection?

to make Well cook the meats. Attention with the bleeding meats, in particular the ground beef. Indeed, if the bacterium is present at the surface of a normal steak, during cooking, the bacterium is destroyed quickly in contact with the hot poële. If the steak is chopped, the bacteria present at surface are then distributed in the whole of steak. To destroy the bacterium in the center, an outward journey and return on the poële will not be enough any more. The steak will have to be cooked a long time so that the temperature in the center is sufficient to destroy the bacterium. The disease with the the United States was called besides “disease of the hamburger”.
to wash Well the hands by handling the meat and in contact with animals of farm or people suffering from the affection.
the food having to be eaten believed must be preserved separately food intended to be cooked, and must be carefully washed.
To pay attention to the products not pasteurized like cheeses with believed milk, the apple juice and the cider.
the kitchen utensils and the schemes of work must be carefully washed.
the Lavage of the hands must be systematic before preparing or consuming the meals.
While avoiding drinking the cup during bathes in water where the bacterium is present.
By avoiding the contact with the infested animals (cows, calves, sheep, goats, deer…) especially for the young children.

Epidemics

In France, the epidemiologic monitoring of this grave disease is based on a network of néphropédiatres. Occurred of a SHU a declaration InVS involves. Occurred several grouped case automatically starts an investigation and an epidemiologic alarm near the Head office of health, DDASS and the Head office of the food. This disease belongs to the Infectious illness to obligatory declaration but only within the framework of a collective food Toxi-infection.

In October 2005 in the South-west of the France, about fifteen people (whose majority of children) were poisoned (one less notifies each year than 100 cases). The origin is frozen chopped meat, “mark Repère” (label given by the grouping E.Leclerc) Chantegrill® sold in the Leclerc centers, coming from a contamination with Escherichia coli O157: H7. The accused batches, carrying the numbers L231 and L234, came from a slaughter-house of Maine-et-Loire. The Traceability allowed to find the error which has occurred. It is the National Sanitary Surveillance Institute (InVS) which began an epidemiological investigation in front of which has occurred brought closer in time and space to two cases of haemolytic and uremic syndrome. On the whole, 18 people presented a SHU (for 69 poisoned people).

See too

Food poisoning

External bonds

Cases grouped of SHU and bloody diarrheas with E. coli O157 H7, Western South, October 2005, site of the InVS

not of October 30th, 2005
not of October 31st, 2005
final point at the Genetic January 13rd, 2006

and physiopathology of the haemolytic and uremic syndrome (SHU) and of will purpura thrombotic thrombocytopenic (PTT)

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