Listeria Infection in Pregnancy: A Review of Literature

Listeria monocytogenes, a Gram-positive bacterium, is responsible for human listeriosis. Infection with Listeria has been associated with the consumption of contaminated and/or inadequately cooked food, particularly dairy products, leafy vegetables, fish, and meat. The main clinical manifestations include diarrhea, nausea and vomiting, which are usually followed by fever and flu-like symptoms. Listeriosis affects pregnant women in about one in seven (14%) cases. They are approximately 10 times more likely to catch the disease than the general population. Although Listeria infection during pregnancy is usually uncomplicated for the mother, fetal and neonatal infection can be severe and fatal. Animal studies have shown a dose-response relationship between L. monocytogenes bacterial load and adverse pregnancy outcome, mainly pregnancy loss. Fetal and neonatal infection occurs through the transplacental passage of the bacterium or through exposure in the perinatal period. In pregnant women Listeria infection was associated with fetal loss, preterm birth, neonatal infection or neonatal death. Blood culture is the principal diagnostic tool and the antibiotic of choice for the treatment of listeriosis is penicillin, with high doses injected intravenously for at least 14 days. In case of suspected or confirmed maternal listeriosis, a program of fetal surveillance should be implemented. Common fetal ultrasound findings in listeria infection include non-immune hydrops, intracranial calcifications, and intrauterine fetal demise. Strategies for the prevention of listeriosis, including avoiding unpasteurized dairy products, uncooked food and leftover food, have significantly decreased the number of cases of infection. Prevention in pregnant women can be achieved by sticking to prophylactic measures and strict diet recommendations.