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Listeria Monocytogenes

Listeriosis is caused by Listeria monocytogenes, a gram-positive bacillus common in the environment and acquired by humans primarily through consumption of contaminated food. Infection causes a spectrum of illness, ranging from febrile gastroenteritis to invasive disease, including sepsis and meningoencephalitis. Invasive listeriosis occurs predominantly in older adults and persons with impaired immune systems. Listeriosis in pregnant women is typically a mild "flu-like" illness, but can result in fetal loss, premature labor, or neonatal infection. Listeriosis is treated with antibiotics.

Exposure to Listeria is common, but the risk of invasive disease is low. Most experts agree that no testing or treatment is indicated for an asymptomatic person who ate a food product that was recalled because of L. monocytogenes contamination. These patients should be instructed to return for medical care if symptoms develop within 2 months of eating the recalled produce. In patients with suspected disease, blood samples should be drawn for culture.

An exposed person with elevated risk of invasive listeriosis who develops fever (>100.6° F, >38.1° C) and signs and symptoms consistent with listeriosis, should be tested and treated for presumptive listeriosis. Diagnostic testing includes blood cultures and other tests, such as culture of cerebrospinal fluid, depending on the clinical presentation. Preferred treatment is a 14 to 21 day course of IV ampicillin or gentamicin. Antibiotic therapy can be discontinued when blood cultures become negative and symptoms resolve.

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