facultative intracellular anaerobe
replicate at cold temperatures (eg, refrigeration) and invade the intestinal mucosa once ingested, causing gastroenteritis (eg, fever, vomiting, diarrhea).
| Pathogenesis | • Food-borne transmission( eg, deli meats). • Bacterial invasion of intestinal epithelial cells • Transplacental passage to fetus | | --- | --- | | Clinical features | • Febrile gastroenteritis (Nausea, watery diarrhea) in immunocompetent host • Invasive disease (eg, sepsis, meningitis) in neonates, pregnant women, elderly, immunocompromised | | Laboratory findings | • Gram-positive rods on culture (eg, stool, blood, CSF) | | Treatment | • Supportive care for gastroenteritis in normal host • Parenteral antibiotics for invasive disease |
Maternal infection with Listeria monocytogenes typically presents with a febrile gastroenteritis. Vertical transmission usually causes sepsis in the neonatal period due to exposure during delivery, but transplacental transmission can occur, typically causing disseminated abscesses.
fetal infection generally results in spontaneous abortion or preterm delivery of a fetus with multiple abscesses and granulomas (ie, granulomatous infantiseptica). Ultrasound findings typically include dilated loops of bowel and ascites.
Most infections in healthy patients are self-limited; however, pregnant women (who are relatively immunosuppressed) are at increased risk of invasive disease (eg, bacteremia) and fetal infection via transplacental transmission. Infection acquired in early pregnancy (eg, first and second trimesters) typically results in granulomatosis infantiseptica (ie, disseminated abscesses/granulomas) and possible intrauterine fetal demise. Infection in the third trimester may be less severe and present as fetal distress, preterm delivery, or early-onset neonatal sepsis. Therefore, pregnant patients are advised to avoid foods commonly contaminated with L monocytogenes such as raw meats and vegetables, unpasteurized dairy products, and processed (eg, deli) meats. In addition, proper handwashing after handling soil or decaying vegetation (eg, gardening) is recommended.
Consumption of unpasteurized milk products is a risk factor for listeriosis, which typically manifests with self-limiting gastroenteritis in healthy adults. In pregnant women, however, listeriosis can cause complications (e.g., fever, chorioamnionitis, PPROM) and result in preterm birth or spontaneous abortion. Transmission from an infected mother to the fetus can either occur transplacentally or via direct contact with infected vaginal secretions and/or blood during delivery. This patient likely has early-onset neonatal listeriosis (granulomatosis infantiseptica), manifesting with severe systemic infection and disseminated organ involvement (i.e., of the liver and lungs). Signs of meningitis (e.g., fever, seizures, hypotonia, abnormal cerebral ultrasound) may develop as early as seen here, especially in preterm neonates, or have a delayed onset in the 3 weeks after birth, typically in full-term neonates with perinatal infection. Both mother and newborn should be treated with IV ampicillin and gentamicin.
(Choice E) Staphylococcus aureus is a rare cause of intrauterine fetal demise and gastrointestinal symptoms. Patients typically have gastroenteritis dominated by nausea and vomiting (rather than diarrhea), making this diagnosis less likely.