Listeria (Bacteria) Flashcards
What are the family characteristics of Listeria?
Gram +, non spore forming rods. They are facultative intercellular with TUMBLING MOTILITY and are ß hemolytic (against diphtheroids).
Which is the listeria species of medical importance?
Listeria Monocytogens.
What are the distinguishing features of listeria monocytogens?
Small, gram + rods. Beta hemolytic, non-spore forming rods, tumbling motility in broth, actin jet motility in cells (by inducing actin to polymerize and basically ride the actin polymer like a skateboard onto the next cell). Thus, lateral propulsion from cell to cell.
Whats one way Listeria monocytogens can escape ABX?
It is a facultative intracellular organism, so it can escape inside our cells to avoid ABX.
How does the cold affect Listeria?
It doesn’t, it can grow in the cold.
What is the reservoir of Listeria monocytogenes?
It’s widespread in animals, livestock, in their GI and GU tracts, also in soil and water. Found in unpasterurized milk and dairy products, plants and soil.
How can humans get Listeria Monocytogenes?
From unpasteurized milk and dairy products like soft cheese, deli meats, cabbage (cole slaw) hotdogs, etc.
Transmission of L. Monocytogenes?
Foodborn, vertical transmission from mother to fetus, and can also cross placenta.
What is the pathogenesis of Listeria Monocytogenes?
Listeriolysin O, which is a ß hemolysin. And if immunologic immaturity is present the infection gets worse.
What are the signs/symptoms of Listeriosis?
Healthy adults and children will be fine, maybe have mild diarrhea w/ low percentage carriage. However preggos can get septic and the sepsis can cross the placenta. Neonates however have much more severe presentations of two types: early onset and late onset.
What is “Granulomatous Infantisepticum”?
It is the early onset version of neonatal disease, in which there is in utero transmission. There is sepsis with high mortality, disseminated granulomas with central necrosis.
What is the “Late onset” disease caused in neonates from M. Listeria?
2-3 weeks after birth this presents with fecal exposure, and will present with meningitis with septicemia.
What are the diseases Listeria can cause in immunocomprimised patients?
Sepsis and Meningitis, particularly in renal transplant patients and patients in anti-cancer drugs. This is the most common cause of meningitis in the renal transplant pt’s and adults in anti cancer drugs.
How would one Dx Listeria?
Culture of the blood or CSF.
Tx of Listeria?
Ampicillin w/ Gentamycin if immunocomprimised.
