Babies born to mothers who become infected with listeria at the end of pregnancy are usually born prematurely and tend to have respiratory failure with pneumonia.

Listeria infection is acquired by the intake of contaminated food. It is a bacterium resistant to low temperatures.

In a pregnant woman, once the contaminated food is ingested, the listeria is absorbed into the digestive system and reaches the placenta, one of her favorite tissues.

What are the symptoms of listeria infection?

However, in the case of pregnant women it is serious, as it can cause consequences on the fetus.
The symptoms of this infection are nonspecific, being able to appear discomfort and fever as if it were a flu. However, in some cases, a picture of gastrointestinal symptoms such as nausea and abdominal pain is previously presented.

Under normal conditions, it is an unspecific picture with no more importance. However, in the case of pregnant women it is serious because of the consequences it can have for the baby.

If the infection is acquired in the first or second trimester of pregnancy, in many cases an abortion or intrauterine fetal death usually occurs.

Of the 80% of cases in which it occurs in the third trimester, in a third part it is totally asymptomatic for the mother and the baby. So, in two thirds there is an infection of the amniotic fluid and premature delivery, with a baby mortality of about 20%.

How is the baby spread?

Babies born to mothers who become infected with listeria at the end of pregnancy can be infected in two ways:

* Through the blood: it is the most frequent form and appears on the second or third day of life. They are usually babies born in premature births and who have respiratory failure with pneumonia.

* By contagion in the birth canal: in these cases it appears on the seventh day of life. Often, babies have meningitis.

Diagnosis of listeria infection in pregnancy

Sometimes, it is very difficult to diagnose, since symptoms are very common in many diseases. The diagnosis is made by isolating the bacteria in the pregnant woman, the placenta or the newborn.

In the first and second trimester of pregnancy you can give flu-like symptoms, with fever and gastrointestinal symptoms. However, in the third trimester it usually presents as a picture of fever, uterine pain and contractions.


Given the suspicion of listeria in the pregnant woman, it is essential to start antibiotic treatment as soon as possible. Often, intravenous ampicillin is chosen.

The treatment of choice is intravenous ampicillin in doses of 1g/8h for at least 10 days . Subsequently, continue orally until completing 3 weeks of treatment. In addition, an intravenous aminoglycoside is administered in doses of 3mg / kg in a single daily injection for 5 days.

Proper application of antibiotic treatment significantly improves the prognosis and can prevent neonatal infection. If a listeria infection is suspected in a pregnant woman, antibiotic treatment should be started before having the results of the cultures so as not to waste time.

How can listeria infection be prevented?

Prophylaxis must take into account all links in the pollution chain. The most important preventive measure is information to pregnant women about the risk of infection related to food and hygienic measures.

Above all, you should be very careful with food and keep in mind that listeria is resistant to freezing. However, this bacterium is destroyed above 50°.

Here are some recommendations to prevent listeria infection:

* Cook all foods of animal origin above 50º and take pasteurized dairy.

* Wash foods that are eaten raw well. You should also wash your hands, kitchen utensils and kitchen surfaces after handling raw food.

* Clean the refrigerator often and do not combine raw and cooked food.

* Do not keep charcuterie products for a long time after opening.

* Foods not recommended in pregnancy

* The foods most at risk of being infected by listeria and, therefore, are not recommended for pregnant women are:

* Soft cheeses that are not pasteurized, brie or camembert type.

* Unpasteurized milk

* Frankfurter sausages if they do not heat well above 50ºC.

* Raw fish and seafood.

* Purchased salads ready to eat.

* Before consuming them it is recommended to wash them well.


The importance of listeriosis derives from the serious consequences that a late diagnosis can have on the evolution of pregnancy. So it is important to keep it in mind before any febrile process with no apparent focus during pregnancy.

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