Domain: Bacteria

Family: Listeriaceae

Genus: Listeria

Order: Bacillales

Phylum: Bacillota

Species: L. monocytogenes

Listeria is most likely to sicken pregnant women and their newborns, adults aged 65 or older, and people with weakened immune systems. Other people can be infected with Listeria, but they rarely become seriously ill.

**Pregnant Hispanic women are 24 times more likely than the general population to get Listeria infection.

• Pregnant women are 10 times more likely than other people to get Listeria infection.

• Pregnant Hispanic women are 24 times more likely than other people to get Listeria infection.

• Listeria infection can cause miscarriages, stillbirths, and preterm labor.

• Listeria infection can cause serious illness and even death in newborns.

The bacteria are most likely to sicken people who are pregnant and their newborns, adults aged 65 or older, and people with weakened immune systems. Other people can be infected with Listeria, but they rarely become seriously ill.

Invasive illness

Invasive means bacteria have spread beyond the intestines (gut). Invasive listeriosis happens when Listeria have spread beyond the intestines.

Symptoms of invasive illness usually start within 2 weeks after eating food contaminated with Listeria.

Symptoms of invasive illness

People who are pregnant

Symptoms typically include

• Fever

• Flu-like symptoms, such as muscle aches and fatigue

People who are not pregnant

Symptoms typically include

• Fever

• Flu-like symptoms, such as muscle aches and fatigue

• Headache

• Stiff neck

• Confusion

• Loss of balance

• Seizures

  
  

L. monocytogenes endophthalmitis typically presents with eye pain, elevated intraocular pressure (IOP) and a fibrinous anterior chamber reaction. We present a case of endogenous L. monocytogenes endophthalmitis in a healthy man who recovered 20/20 vision after aggressive treatment with local and systemic antibiotics and anterior chamber washout.

Listeria monocytogenes infects approximately 1,600 people in the U.S. each year, killing roughly 20% of them — making it one of the deadliest pathogens found in food.

Unfortunately for food manufacturers and operations with salad bars and delis, Listeria is a particularly dangerous pathogen. This is because many raw items such as meats, poultry, seafood, and some fruits and vegetables may carry Listeria monocytogenes – a microorganism that not only survives but can also grow at cold temperatures which makes these types of establishments especially vulnerable to contamination.

Improper or infrequent cleaning and sanitizing can allow Listeria monocytogenes to grow to high levels in these settings. The pathogen often hides in cracks and crevices on surfaces and equipment, leading to cross-contamination of ready-to-eat foods.

According to the Food Safety and Inspection Service, here are a few “Best Practices for Controlling Listeria monocytogenes”:

• Develop detailed written sanitization procedures for equipment

• Clean and sanitize utensils and equipment used with ready-to-eat foods frequently

• Ensure proper levels of sanitizer concentration

• Prevent spreading bacteria via contaminated reusable cleaning tools (e.g., rags, sponges, mops)

Other important distinguishing properties of this organism are as follows;

1. It shows tumbling type of motility at 25°C but non-motile at 37°C (called differential motility, which is due to the temperature-dependent flagella expression).

2. Unlike most other harmful bacteria, L. monocytogenes grow slowly on foods stored in a refrigerator (4°C). It is commonly found in stored foods especially aged soft cheeses, packaged meats, milk, and cold salads.

3. Growth improves if the specimen is refrigerated at 4°C and cultured at frequent intervals, this procedure is called cold enrichment.

4. It shows a positive CAMP test when streaked at a right angle to beta-hemolytic Staphylococcus aureus (enhanced arrowhead hemolysis).