Listeria infection, also referred to as listeriosis, is a relatively rare bacterial infection that results from Listeria monocytogenes, a type of gram-positive motile bacterium. Listeria infection commonly affects newborn infants, elderly patients, and individuals with immuno deficiencies.

In cases of CNS infection, the L. monocytogenes can usually be cultured from the blood. No reliable stool or serological tests are known to date. Treatment for bacteremia often lasts for 2 weeks. Meningitis must be treated for 3 weeks, while 6 weeks is the minimum for brain abscess. The antibiotic of choice is usually ampicillin. Gentamicin may also be added for its synergistic effects.

There are 4 clinical syndromes identified with listeria infection. The first is infection during pregnancy. In such cases, listeria can spread asymptomatically in the uterus and the vagina. The mother usually becomes symptomatic only in the last trimester of her pregnancy. Fever, headaches, arthralgias, and myalgias are common symptoms. Complications in the form of stillbirth, abortion, or preterm labor may occur. Neonatal infection, which comes in two forms, is another syndrome of listeriosis. The first form is early onset sepsis, wherein listeria is acquired in the utero. This often results in premature birth. The other form, late onset meningitis, is acquired through vaginal transmission. The third listeria syndrome, CNS infection, is characterized by a predilection for the parenchyma of the brain, particularly in the meninges and brain stem. CNS infection may lead to encephalitis, meningitis, cranial nerve palsies, meningoencephalitis and abscesses. Afflicted individuals typically experience changes in mental status, with seizures occurring in roughly a quarter of known cases. The last syndrome, gastroenteritis, is caused by L monocytogenes producing diarrheal disease borne in food. This is usually noninvasive and has a median incubation period of 24-48 hours. Diarrhea can last between 1-3 days. Afflicted patients often experience muscle aches, fever, gastrointestinal nausea or diarrhea, stiff neck, headache, loss of balance, confusion, or convulsions.

Listeria infection is caused by acquiring listeria monocytogenes, which are abundant in the environment. Listeria monocytogenes are often ingested through food products that are contaminated. Main sources of this bacterium are dairy products, raw meat, seafood, and vegetables.

listeriainfection