Listeriosis

Definition
Listeriosis is a disease caused by infection with the organism Listeria monocytogenes.

Causes, incidence, and risk factors
Listeria monocytogenes is common in wild animals, domesticated animals, and in soil and water. L. monocytogenes causes disease in many animals and is a common cause of miscarriage and stillbirth in domestic animals. L. monocytogenes also occurs as a food-borne contaminant that can cause disease.

In humans, L. monocytogenes most often causes a generalized blood infection (septicemia) or meningitis (inflammation of the covering of the brain). The fetus, newborn, and pregnant women are particularly susceptible to L. monocytogenes. Immunocompromised individuals, such as those being treated for cancer, those with organ transplants, and those with AIDS are at increased risk.

Infection of a pregnant woman early in pregnancy generally leads to miscarriage. The organism may be transmitted across the placenta. Infections in late pregnancy may lead to stillbirth or death of the infant within a few hours of birth. About half of infants infected at or near term will die.

In infants, listeriosis may become evident in the first few days of life with loss of appetite, lethargy, jaundice, vomiting, respiratory distress, and shock. Infants usually have pneumonia. A skin rash may be present. The death rate is very high.

Late-appearing infection in the infant (symptoms appear at age 5 days or older) and infection in children is often seen as meningitis. There are no special clinical signs to differentiate listerial meningitis from other types of meningitis.

In adults, the disease may take many forms depending on what organ or organ systems are infected. It may occur as meningitis, pneumonia, septicemia, and endocarditis or in milder form as abscesses, skin lesion, and conjunctivitis.

Symptoms
Maternal infection while pregnant leading to:

     
  • stillbirth  
  • fulminant illness in the newborn causing death within a few hours of birth

In the newborn:

     
  • loss of appetite  
  • lethargy  
  • jaundice  
  • vomiting  
  • skin rash  
  • increased pressure inside the skull (due to meningitis) may cause the skull’s “sutures” to become separated

Signs and tests

     
  • brown-stained amniotic fluid  
  • skin rash  
  • respiratory distress  
  • shock

Tests:

     
  • cultures of amniotic fluid  
  • cultures of the blood  
  • cultures of the urine (clean catch)  
  • CSF culture

Treatment
Treatment is aimed at eliminating the infection with antibiotics. Antibiotics prescribed may include:

     
  • Intravenous ampicillin combined with gentamicin  
  • Trimethoprim-sulfamethoxazole is used as an alternative therapy

Expectations (prognosis)
Infection of the fetus with L. monocytogenes results in a poor outcome with approximately a 50% death rate. The late infant onset form also has a high death rate. Healthy older children and adults have a lower death rate.

Complications

In addition to severe disease, stillbirth, and death as described above, infants who survive listeriosis may suffer long-term neurological damage and delayed development.

Calling your health care provider
Call your health care provider if signs or symptoms of Listeriosis develop in you or your child.

Prevention

Pregnant women should avoid contact with wild and domestic animals. Listeria is well controlled in American food products, but food-associated outbreaks have occured.

Pregnant women should avoid consumption of soft cheeses, deli meats, and cold salads from salad bars. Foreign food products such as nonpasteurized soft cheeses have also been implicated in outbreaks of listeriosis. Food should always be adequately cooked.

Johns Hopkins patient information

Last revised: December 3, 2012
by Martin A. Harms, M.D.

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