All species within the genus Listeria are gram-positive, catalase -positive rods and do not produce endospores. Under the microscope, Listeria species appear as small rods, sometimes arranged in short chains. In direct smears, they may be coccoid, and can be mistaken for streptococci. Longer cells may resemble corynebacteria.

Named for Joseph Lister, Listeria monocytogenes is a Gram-positive bacterium, in the phylum Bacillota. Its ability to grow at temperatures as low as 0 °C permits multiplication at typical refrigeration temperatures, greatly increasing its ability to evade control in human foodstuffs.

Sep 10, 2023 · Diagnosis: positive CSF Gram stain ~30%, CSF culture ~85%, CSF PCR ~60%, BCx +63%; Manifestations: Meningoencephalitis (~87%) Meningitis alone (~13%) Brainstem encephalitis/rhomboencephalitis (~17%) Other presentations: Brain abscess, cranial nerve deficits, cerebellar signs, and/or hemiparesis.

Aug 12, 2024 · Learn the clinical features of invasive listeriosis, which depend on the patient. Listeria monocytogenes is a facultatively anaerobic, rod-shaped, gram-positive bacterium. It can be readily isolated in standard bacterial culture of normally sterile body sites.

Listeria is a short gram-positive rod that occurs singly or in short chains. However, the identification of Listeria on Gram stain may be challenging. Listeria may resemble pneumococci (diplococci) or diphtheroids (Corynebacteria) or be gram variable and confused with Haemophilus species (picture 1) [3-5].

Listeria are small, non–acid-fast, noncapsulated, nonsporulating, beta-hemolytic, aerobic, and facultative anaerobic gram-positive bacilli that have characteristic tumbling motility. They are present worldwide in the environment and in the gut of …

May 24, 2021 · All gram-positive rods isolated from blood and CSF should be identified to distinguish between Corynebacterium (presumably a contaminant) and Listeria. Biochemical Test of Listeria monocytogenes Catalase: positive

Listeria monocytogenes is a small, facultative anaerobic, nonsporulating, gram-positive rod. It grows best at temperatures of 30 to 37°C, but it grows well at colder (refrigerator) temperatures, and in the laboratory can be separated from other bacteria by taking advantage of this fact, a technique known as cold enrichment (97).

Jul 22, 2023 · Gram Staining: Listeria monocytogenes is gram-positive, meaning it retains the crystal violet stain during the Gram staining procedure. When viewed under a microscope after Gram staining, the cells will appear purple. Motility: It is …

Listeria monocytogenes is a facultative intracellular Gram-positive coccobacilli responsible for listeriosis, one of the serious food-borne infections. Other important distinguishing properties of this organism are as follows;