Difference Between Listeria Monocytogenes and Listeria Spp

The key difference between Listeria monocytogenes and Listeria spp is that L. monocytogenes is a foodborne human pathogenic species of the genus Listeria while Listeria spp is a member of the Listeria genus that contains 21 species, including pathogenic L. monocytogenes and non-pathogenic Listeria innocua.

The genus Listeria belongs to the class Bacilli and the order Bacillales. Bacillus and Staphylococcus also belong to the same class and order. This genus was named after Joseph Lister. This genus contains 21 species as of 2021. Some of them are L. monocytogenes, L. innocua, L. ivanovii, L. marthii, L. aquatica, L. booriae, L. cornellensis, L. costaricensis, L. goaensis, L. Seeligeri and L. thailandensis. This genus has both pathogenic and non-pathogenic species. For example, L. monocytogenes is a pathogenic bacterium that causes listeriosis. On the other hand, L. innocua is generally not infectious.

CONTENTS

1. Overview and Key Difference
2. What is Listeria Monocytogenes
3. What is Listeria Spp
4. Similarities Between Listeria Monocytogenes and Listeria Spp
5. Side by Side Comparison – Listeria Monocytogenes vs Listeria Spp in Tabular Form
6. Summary

What is Listeria Monocytogenes?

Listeria Monocytogenes is a foodborne human pathogenic species of genus Listeria, which is gram-positive, rod-shaped, and facultatively anaerobic. They cause an infection called listeriosis. Listeriosis is a bacterial infection that can cause severe illness, including sepsis, meningitis, or encephalitis. Sometimes, it results in lifelong harm and even death. Specifically, the elderly, newborns and immunocompromised are at a greater risk of this infection. L. monocytogenes is identified as a foodborne pathogen. It is responsible for an estimated 1,600 illnesses and 260 deaths in the United States, annually. It grows at lower temperatures as 00C, which increases the potential risk of infection. L. monocytogenes contain virulent factors such as listeriolysin, phospholipases, internalin, and ActA protein. Lisetriolysin and phospholipases help bacteria to escape from the phagocytotic vacuole. The internalin mediates the bacterial adhesion and invasion of epithelial cells in the human. ActA protein increases cell mobility intracellularly.

Figure 01: L. monocytogenes

Listeria selective agar media, DNA probes, or ELISA are used to detect this organism in the pathogenic environment. Penicillin, ampicillin, and trimethoprim-sulfamethoxazole have been shown effective against Listeria infection.

What is Listeria Spp?

Listeria is a genus of are gram-positive, rod-shaped, facultatively anaerobic, intracellular pathogens in mammals. Listeria spp is any member of this genus. This genus contains 21 species, including pathogenic and non-pathogenic bacteria. Listeria species are mainly found in soil, water, vegetation, effluents, and a broad range of food.

The twenty-one species that include this genus are L. monocytogenes, L. newyorkensis, L. riparia, L. rocourtiae, L. seeligeri, L. thailandensis, L. valentina, L. weihenstephanensis, L. welshimeri,L. innocua, L. ivanovii, L. marthii, L. aquatica, L. booriae, L. cornellensis, L. costaricensis, L. goaensis, L. fleischmannii, L. floridensis, L. Grandensis and L. grayi. Certain Listeria spp cause severe listeriosis. Some of them are  L. monocytogenes, L. ivanovii and L. grayi. From 2011 to 2019, these bacteria caused outbreaks in the US, Europe, South Africa and Spain.

Figure 02: Listeria spp

Antibiotics such as ampicillin, penicillin, amoxicillin, erythromycin, trimethoprim-sulfamethoxazole, vancomycin, and fluoroquinolones can be used for treatment. Some species of this genus are non-pathogenic. L. Innocua is an example of non-pathogenic Listeria. The common methods that are used in the laboratories to detect Listeria are culture-based methods, PCR tests and ELISA. Researchers are now experimenting with the possibility of using Listeria as a cancer vaccine. This is because of its ability to induce potent innate and adaptive immunity.

What are the Similarities Between Listeria Monocytogenes and Listeria Spp?

• Both are gram-positive, rod-shaped, facultative anaerobes.
• Both are intracellular.
• They cause human infections.
• Both of them can be identified through selective culture media, PCR or ELISA tests-based methods.

What is the Difference Between Listeria Monocytogenes and Listeria Spp?

Listeria monocytogenes are a foodborne human pathogenic species of the genus Listeria. Listeria spp is a member of the genus Listeria that contains 21 species, including pathogenic L. monocytogenes and non-pathogenic Listeria innocua. Thus, this is the key difference between Listeria monocytogenes and Listeria spp. Moreover, L. monocytogenes can be mainly found in contaminated food. In contrast, Listeria species are mainly found in soil, water, vegetation, effluents, and a broad range of foods.

The below infographic lists the differences between Listeria monocytogenes and Listeria spp in tabular form.

Summary – Listeria Monocytogenes vs Listeria Spp

Listeria monocytogenes is a species of genus Listeria that causes the infection listeriosis in human. Listeria spp are gram-positive, rod-shaped, facultative anaerobic bacteria belonging to the Listeriaceae family and composed of 21 species. They include Listeria monocytogenes, which is pathogenic for humans (foodborne illness) and rarely for animals like ruminants. They also have species like Listeria ivanovii which is pathogenic for animals but rarely for humans, and species like L. innocua, which is non-pathogenic. Thus, this is the summary of the difference between Listeria monocytogenes and Listeria spp.

Reference:

1. “Listeria Spp and Listeria Monocytogenes: A Harmful Bacteria Causing Rare but Severe Foodborne Diseases.” BioMérieux Industrial Microbiology, 2 July 2020, Available here.

Image Courtesy:

1. “Listeria monocytogenes, infectieuse, l’agent, la nourriture, la charge, la maladie, la listériose” (CC0) via Pixino
2. “Listeria” By Search-boy – Own work (CC BY-SA 4.0) via Commons Wikimedia

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