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Listeriosis in Newborns

By

Brenda L. Tesini

, MD, University of Rochester School of Medicine and Dentistry

Last full review/revision Jul 2020| Content last modified Jul 2020
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Topic Resources

Listeriosis is infection caused by the bacteria Listeria monocytogenes.

  • Listeriosis in newborns can be acquired in the womb or during or after delivery.

  • Symptoms vary but may include listlessness and poor feeding.

  • The diagnosis is confirmed by identifying the bacteria in a sample of blood or other material taken from the newborn and mother.

  • Some newborns die from the infection.

  • Pregnant women should avoid certain foods and properly wash their hands and kitchen equipment after handling uncooked foods.

  • Antibiotics can cure the infection.

The Listeria monocytogenes bacteria resides in the intestine of some people and many animals worldwide. Unlike many other organisms, it survives well at refrigerator temperatures.

Pregnant women can become infected if they eat contaminated food. These foods include unpasteurized dairy products, soft cheeses, raw vegetables, prepared deli meats and salads, refrigerated meat spreads, or smoked seafood. Fetuses become infected if Listeria monocytogenes crosses the placenta (the organ that provides nourishment to the fetus) during pregnancy. Newborns may become infected during or after delivery.

Symptoms

Pregnant women with listeriosis may show no symptoms, or they may have symptoms resembling the flu (for example, chills, fever, and muscle aches).

In fetuses and newborns, symptoms of listeriosis are like those of sepsis (a blood infection) and include listlessness and poor feeding. Symptoms may appear within hours or days of birth (called early onset) or may be delayed up to several weeks (called late onset). Newborns who have symptoms that appear early frequently have a low birth weight, problems at delivery, and symptoms of sepsis soon after birth. Newborns who have symptoms that appear late are usually full-term and initially healthy but then develop meningitis (a brain infection) or sepsis.

Other common complications of listeriosis include miscarriage, premature delivery with intra-amniotic infection, and stillbirth.

Diagnosis

  • Testing of blood and other fluids taken from pregnant women and newborns

In pregnant women who have a fever, samples of blood, material from the cervix, and amniotic fluid may be removed and tested for Listeria monocytogenes.

If a newborn is sick, samples of blood and spinal fluid (obtained with a spinal tap—see figure How a Spinal Tap Is Done) are collected and tested for Listeria monocytogenes. If a newborn is sick and the mother definitely had listeriosis, samples of blood and spinal fluid in addition to fluid from the stomach, meconium (fecal material that is produced in the intestine before birth), and infected tissues are also collected and tested for Listeria monocytogenes.

The samples are sent to a laboratory to grow (culture) the bacteria or to undergo the polymerase chain reaction (PCR) test. The PCR test looks for the genetic material of the bacteria and enables doctors to rapidly identify the bacteria. Identifying the bacteria in a sample confirms the diagnosis.

Prognosis

About 10 to 50% of newborns with listeriosis die. The death rate is higher among newborns who have early-onset listeriosis.

Prevention

Pregnant women should avoid the types of foods that are more likely to be contaminated by Listeria monocytogenes. Foods to avoid include unpasteurized dairy products, soft cheeses, raw vegetables, prepared deli meats and salads, refrigerated meat spreads, and smoked seafood. Proper food handling, in particular separating uncooked meats from other items during preparation, and washing hands, utensils, and cutting boards after handling uncooked foods are critical.

If listeriosis is diagnosed during pregnancy, doctors may treat pregnant women before delivery or at delivery with antibiotics to help prevent transmission, but the usefulness of such treatment is unproved.

Treatment

  • Antibiotics

Newborns are given the antibiotic ampicillin plus another antibiotic from the class of drugs called aminoglycosides. Newborns who also have sepsis require antibiotics and other treatments.

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