Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
11 Cards in this Set
- Front
- Back
|
What are 5 Gram positive bacteria we studied?
|
Streptococcus, Staphylococcus, Listeria, Nocardia, and Actinomyces
|
|
|
What does it mean that Listeria monocytogenes is gram-variable and pleomorphic?
|
Sometimes, this gram-positive bacteria looks gram-negative.
Sometimes, this rod looks round. |
|
|
What peculiar movement is characteristic of Listeria monocytogenes?
|
Tumbling motility.
Has up to 5 flagella. |
|
|
Describe the microbiology of Listeria in connection with:
- aerobicity - reproduction - catalase - oxidase - environment temperature |
Listeria is
- facultatively anaerobic - non-sporulating - catalase-positive - oxidase-negative - grow optimally at 30-37C but capable of growth at 4-10C |
|
|
What 4 facts support the hypothesis that infection with another gastrointestinal organism is necessary to facilitate L. monocytogenes infection?
|
(1) Patients who get listeriosis frequently report antecedent GI infections too
(2) The long incubation time suggests that L. monocytogenes has a long silent, subclinical phase as colonizers (3) Listeriosis sometimes occurs after other GI infections such as shigellosis (4) Listeriosis sometimes occurs after instrumentation (eg: colonoscopy) of the GI tract |
|
|
What is Listeria's life ambition?
|
To get into a mammalian cell. It is an intracellular pathogen.
|
|
|
What are 5 virulence factors that allow Listeria to be an intracellular pathogen?
|
(1) Internalin (bac surf prot) binding with E-cadherin (mamm epithelial surf prot) promotes phagocytosis
(2) once in cell, listeriolysin O and phospholipases help bac escape intracellular kill'g (3) spreads fr cell to cell w/o ever be'g exposed to Abs, complement, or neutrophils by propel'g toward host cell membrane and form'g filopods that are ingested by adjacent cells (4) Act A: oligoproline-containing surf prot that induces actin filament assembly and cell-cell spread of the bac (5) Siderophores: enable the bac to take iron from transferrin. Iron facilitates the org's growth |
|
|
Considering that siderophores enable Listeria monocytogenes to take iron from transferrin, and iron facilitates its growth, what happens during iron overload (eg: hemochromatosis)?
|
There is an increased susceptibility to Listeria infection
|
|
|
What is the primary type of immunity against L. monocytogenes?
|
Cell-mediated.
Thus, patients with impaired cell-mediated immunity, such as in AIDS or lymphoma, pregnant women, or persons taking corticosteroids, there is an increased risk of infection with Listeria. |
|
|
Why is it not surprising that antibodies to not play an important role in immunity against L. monocytogenes?
|
Because Listeria can be passed from cell to cell without ever encountering antibodies.
Thus, there is no increase in Listeria infections among people who are asplenic, have complement deficiencies, or Ig disorders. |
|
|
Which people are Listeria infections more common in?
|
AIDS patients
slaughterhouse workers |
