What is the incubation period for Listeria monocytogenes?

The incubation period is usually one to two weeks but can vary between a few days and up to 90 days.

What is the infectious pathway for Listeria?

The main route of transmission is oral, through ingestion of contaminated food. Other routes include mother-to-fetus transmission via the placenta or at birth. The infectious dose is unknown.

What is a presumptive positive for Listeria?

Laboratories generally give results as “presumptive positive” or “positive”. Under normal circumstance, presumptive positive means that listeria has been detected on a given sample. This does not indicate if it is living or dead. This test usually takes 24-48 hours (using rapid detection methods not cultural).

What is the temperature growth range for Listeria monocytogenes?

between -1.5 and 45°C
In food these include temperature, pH, water activity, salt and the presence of preservatives (refer to Table 1). The temperature range for growth of L. monocytogenes is between -1.5 and 45°C, with the optimal temperature being 30–37°C.

How soon can you test for Listeria?

These symptoms can begin days to weeks after eating contaminated food. A blood test can confirm whether you have been infected with listeriosis. If you have eaten contaminated food and do not have symptoms, some experts feel no special testing or treatment is needed.

How long does it take Listeria to grow in culture?

Listeria grow within 24 hours routinely. CSF cultures in those with meningitis are almost always positive, unless the patient received antimicrobials prior to obtaining the specimen. Blood cultures are often positive in patients with meningitis or brain abscess (>75%).

How long does Listeria take to grow culture?

Unlike most bacteria, Listeria grow well at refrigerator temperature (4-10°C) and, by so-called cold enrichment, can be separated from other contaminating bacteria by long incubation in this temperature range. Listeria grow within 24 hours routinely.

How do you test to see if you have listeria?

A blood test is often the most effective way to determine whether you have a listeria infection. In some cases, samples of urine or spinal fluid will be tested as well.

How long does Listeria live at room temperature?

Many foods that are left sitting out for a few hours at room temperatures — especially meats, cut fruit, and dairy foods — are risky. “At room temperature, listeria will double every 20 minutes,” Buchanan says.

Do pregnancy-associated cases of listeriosis have a longer incubation period?

A much longer incubation period was observed for pregnancy-associated cases than for cases with other clinical forms. This information has implications for the investigation of food borne listeriosis outbreaks as the incubation period is used to determine the time period for which a food history is collected.

Is Listeria monocytogenes a public concern?

Although the number of cases of listeriosis is low, the high rate of death associated with the infection makes it a public concern. Unlike the other common foodborne diseases, Listeria monocytogenes survive and multiply at low temperature usually found in refrigerators.

What is the history of Listeria infection?

After going through several name changes since the bacteria were first described in 1911, the name was officially changed to Listeria monocytogenes in 1940 to honor Joseph Lister, the British surgeon who discovered that sterilizing surgical instruments before operations reduced the risk of infections.

Does Listeria go away on its own?

The illness is usually mild and goes away on its own. The diarrhea can last up to 5 days. The elderly and people with weakened immune systems have a higher risk of getting a more severe form of listeriosis, including: Inflammation of the membranes surrounding the brain and spinal cord (meningitis); and