Listeria

Front 1

What is the gram stain, oxygen requirements, and shape of Listeria?

Back 1

Small gram-positive coccobacilli that are facultative anaerobes

Front 2

What condition is Listeria able to withstand that most microbes aren't?

Back 2

Listeria likes cold temperatures (it is able to grow in the refrigerator)

Front 3

What is the major virulence factor for Listeria and what does it allow the organism to do?

Back 3

Listeriolysin allows the bacrterium to lyse the phagosomal membrane to escape the phagesome within macrophages and enter the cytoplasm where it can reproduce

Front 4

Where is Listeria found within the body?

Back 4

It is found within macrophages

Front 5

Describe the activity of the ActA protein secreted by Listeria

Back 5

ActA protein causes the polymerization of actin filaments which bind to the bacterium and allow for intracellular movement; the bacterium can spread from cell-to-cell without going into the extracellular environment

Front 6

Describe the habitat of Listeria

Back 6

It is found in soil, water, sewage, feces of domist animals and as normal flora or disease

Front 7

How is Listeria generally transmitted?

Back 7

It is transmitted as a food-borne illness via ingestion of food that is contaminated with the organism; it can also be transmitted transplacentally from mother to fetus

Front 8

What is the major epidemiological factor concerning Listeria infection?

Back 8

It is associated with processed food such as milk, hot dogs, lunch meat, and vegetables

Front 9

What are the most important factors on which the degree of Listeria infection depends?

Back 9

The amount of bacteria ingested (dose), the age of the person and the immune status

Front 10

Describe the steps of Listeria infection

Back 10

Ingestion of bacteria in food, replication in intestinal epithelium and invasion into the submucosa, replication in macrophages, bloodstream invasion and spread to meninges (in immunocompromised), possible transplacental spread in pregnant women

Front 11

What are the symptoms of a Listeria infection?

Back 11

The symptoms depend on the health status of the patient and can be asymptomatic or flu-like with nausea and vomiting

Front 12

Describe Listeria infection in health adults

Back 12

It is usually asymptomatic or mild flu-like diarrheal illness

Front 13

Describe listeria gastroenteritis and whom it affects

Back 13

Listeria gastroenteritis is found in healthy adults after eating a large dose of Listeria and shows intestinal manifestations such as nausea, vomiting, fever

Front 14

Describe Listeria infection in the immunocompromised, elderly, or neonates

Back 14

This is a severe invasive disease with a 2-3 week incubation period that occurs after eating a small dose of Listeria; bloodstream invasion occurs with septicemia and spread to the meninges (high mortality)

Front 15

How is a diagnosis of Listeria made?

Back 15

Monocytosis of the CSF with gram stain and culture of the blood or CSF

Front 16

Describe Listeria infection in pregnant women

Back 16

Pregnant women have a 20 times higher risk of infection; bloodstream invasion occurs with no systemic maternal symptoms, but transplacental spread to the fetus occurs

Front 17

What are the effects of Listeria infection on a pregnancy and fetus?

Back 17

Listeria can cause 1st trimester abortions, stillbirth, or premature delivery

Front 18

Describe Listeria infection in neonates acquiring the disease transplacentally

Back 18

The onset of septicemia, pneumonia, and meningitis is usually less than two days postpartum and shows high mortality

Front 19

When do Neonates usually get Listeria infection?

Back 19

Early onset occurs in neonates with transplacental acquisition, while late onset (1-2 weeks) occurs when acquired at or soon after birth