L. aquatica L. booriae L. cornellensis L. costaricensis L. farberi L. fleischmannii L. floridensis L. goaensis L. grandensis L. grayi L. ilorinensis L. immobilis L. innocua L. ivanovii L. marthii L. monocytogenes L. newyorkensis L. riparia L. rocourtiae L. rustica L. seeligeri L. swaminathanii L. thailandensis L. valentina L. weihenstephanensis L. welshimeri Listeria is a genus of bacteria that acts as an intracellular parasite in mammals.

[6] The two main clinical manifestations are sepsis and meningitis, often complicated by encephalitis, a pathology unusual for bacterial infections.

[8][9] They proposed the genus Listerella in honour of surgeon and early antiseptic advocate Joseph Lister, but that name was already in use for a slime mould and a protozoan.

The genus Listeria was classified in the family Corynebacteriaceae through the seventh edition (1957) of Bergey's Manual of Systematic Bacteriology.

16S rRNA cataloging studies demonstrated that L. monocytogenes is a distinct taxon within the Lactobacillus-Bacillus branch of the bacterial phylogeny[10] constructed by Woese.

[14][3] Listeria sensu strictu contains L. monocytogenes alongside nine other closely related species: L. cossartiae,[15] L. farberi, L. immobilis,[15] L. innocua, L. ivanovii,[16] L. marthii,[17] L. seeligeri, L. swaminathanii[18] and L. welshimeri.

Listeria sensu lato contains the remaining 18 species: L. aquatica,[19] L. booriae,[20] L. cornellensis,[19] L. costaricensis,[21] L. fleischmannii,[22] L. floridensis,[19] L. goaensis,[23] L. grandensis,[19] L. grayi, L. ilorinensis,[24] L. newyorkensis,[20] L. portnoyi,[15] L. riparia,[19] L. rocourtiae,[25] L. rustica,[15] L. thailandensis,[26] L. valentina[27] and L.

Hemolytic activity on blood agar has been used as a marker to distinguish L. monocytogenes from other Listeria species, but it is not a definitive criterion.

[citation needed] Listeria monocytogenes is commonly found in soil, stream water, sewage, plants, and food.

For example, meat-processing plants producing ready-to-eat foods, such as hot dogs and deli meats, must follow extensive sanitation policies and procedures to prevent Listeria contamination.

[5] Listeria, however, escapes the phagolysosome by lysing the vacuole's entire membrane with secreted hemolysin,[36] now characterized as the exotoxin listeriolysin O.

[33] Some of the foods most commonly implicated in Listeria contaminations include ready-to-eat salads and seafood, deli meats, soft and semi-soft cheese, and frozen vegetables.

[42][45] The Australian company GMI Food Wholesalers was fined A$236,000 for providing L. monocytogenes-contaminated chicken wraps to the airline Virgin Blue in 2011.

[54] Heating of meats (including beef, pork, poultry, and seafood) to a sufficient internal temperature, typically 74 °C (165 °F), will kill the food-borne pathogen.

Treatment includes intravenous delivery of high-dose antibiotics and hospital in-patient care of (probably) not less than two weeks stay, depending on the extent of the infection.

[56] Ampicillin, penicillin, or amoxicillin are typically administered for invasive listeriosis; gentamicin may be added in cases of patients with compromised immune systems.

[57] In cases of pregnancy, prompt treatment is critical to prevent bacteria from infecting the fetus; antibiotics may be given to pregnant women even in non-invasive listeriosis.

Pfaff and Tillet say that listeriosis can cause long-term consequences—including meningitis, preterm labor, newborn sepsis, stillbirths—when contracted during pregnancy.

Asymptomatic patients who have been exposed to Listeria typically are not treated, but are informed of the signs and symptoms of the disease and advised to return for treatment if any develop.

[56] Some Listeria species are opportunistic pathogens: L. monocytogenes is most prevalent in the elderly, pregnant mothers, and patients infected with HIV.

In oncology, researchers are investigating the use of Listeria as a cancer vaccine, taking advantage of its "ability to induce potent innate and adaptive immunity" by activating gamma delta T cells.

However, it has been observed that certain antimicrobial agents such as bacteriophages and enzymes have made promising progress in the effort to eradicate the Listeria biofilm.