Gram-Negative Bacterial Structure and Endotoxin in Human Diseases Flashcards Preview

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Flashcards in Gram-Negative Bacterial Structure and Endotoxin in Human Diseases Deck (52)
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Another name for group A strep is _

Streptococcus pyogenes


What is petechia? In the context of case 3, what is thought to cause it?

Petechia are small red spots (blood clots)


What is the mechanism by which endotoxin causes its damage?

It causes clotting in the capillaries, causing adjacent tissues to die and blood to leak into the tissues


There are 6 microbes that cause meningitis. What are the 2 that cause meningitis in people of all ages?

Streptococcus pneumoniae (all ages)
Neisseria meningitidis (all ages)


There are 6 microbes that cause meningitis. What is the one that causes it in individuals 3 months to 7 years, but is not uncommon due to vaccines? What is the target of the vaccine? What is the significance of 3 months?

Haemophilus influenzae type b
Vaccine targets the capsule of the microbe
3 months is usually when neonates run out of maternal antibodies, and the accompanying protection


There are 6 microbes that cause meningitis. What are the 3 major causes in neonates? Which 2 combine for 80% of cases?

Streptococcus agalactiae (40%)
Escherichia coli (40%)
listeria monocytogenes


What is another name for group B strep?

Streptococcus agalactiae


In the context of case 3, what was the cause of the patient's meningitis?

Neisseria menigiditis


In the context of case 3, what were the reasons (3) that neisseria meningiditis was thought to cause the patient's disease?

– Extremely severe and rapidly progressing illness
– Purpura fulminans
– Cultures ultimately grew Neisseria meningitidis capsule group C


Another name for purpura fulminans is _

Waterhouse-Friderichsen Syndrome)


There are 5 major capsule groups of Neisseria meningiditis that the most common causes of meningitis. What are they? Which is not included in the vaccine and why?

A, B, C, Y and W135
B not included because its capsule is not immunogenic


What is the antibiotic treatment used to treat Neisseria meningiditis?

Cephalosporin (A beta lactam)


Neisseria meningiditis is gram positive or negative? Is it a rod, spirochete, coccus, diplococcous, or other? Encapsulated or not? What defining characteristic would it have under a microscope?

Gram negative
Kidney bean shaped cocci


In case 3, what was regarded as the ultimate cause of death?

Fulminant meningococcemia
Fulminant - rapid onset
meningococcemia - meningococci in the blood


Neisseria meningiditis has a capsule. What is its significance for the organism? How does it attach to the host?

Capsule in antiphagocytic, it doesn't allow proper deposition of antibodies that lead to complement cascade
Neisseria meningiditis attaches by pili


In case 3, all the student were vaccinated for Neisseria meningiditis, including the meningitis group C capsule that infected the patient. Why was this ineffective? What is the new protocol now for a potential Neisseria meningiditis outbreak? Why is this better?

Because the production of IgM antibodies takes 4 days, too slow to help the patient.
Treatment of exposed people with Rifampin
Rifampin penetrates mucosal barriers very well


How is Neisseria meningiditis spread? Of the various capsule groups that cause disease, which is considered sporadic?

Intimate contact
Capsule B


True or false, in the brain, Neisseria meningiditis can lead to pus formation?
True or false, petechia and purpura fulminans are unrelated, and only purpura fulminans can lead to necrosis?

False - Petechia can become purpura fulminans, which can progress to necrosis if untreated


Gram positive cell walls are composed of _ and _. Which remains within the cell wall and which anchors to the PM below? What anchors to the outer membrane?

Lipotechoic acid - anchors
Techoic acid - within murein sac components
Gram + dont have outer membranes


How is the peptidoglycan layer similar and different between gram + and gram -?

Similar - same components
Different - Less cross linked


What are the 2 layers found outside the peptidoglycan layer of the gram - organism? Together, these form the _

Phospholipid layer
Lipopolysaccharide layer
Outer membrane of gram -


What is the periplasm? What types of products may be trapped within the periplasm? Where would the capsule be found in a gram negative organism?

The periplasm is what is between the 2 membranes
Large molecules (above 800 MW)
Outside the outer layer


How is the periplasm related to toxicity in e. coli?

In ecoli, the toxins produced are bigger than 800 MW, therefore they are trapped there until cell division, when they are released


What are the 2 components of the periplasmic space in the gram negative bacteria?

Lipoprotein and think peptidoglycan wall


What are 2 other names for endotoxin? What is its significance? What antibodies can protect against endotoxin?

Endotoxin AKA LPS AKA O-antigen
It is the immunogenic component of gram negative bacteria
Antibodies are not protective against LPS


What are the 2 examples of outer membrane proteins of gram negative bacteria provided? What are their functions?

Porins - Trimers that transport molecules
Secretion systems - Transport virulence factors


How are outer membrane proteins held in the outer membrane (2)?

Either embedded in the membrane or ...
Covalently linked to peptidoglycan


What are the 2 functions of pili in gram negative bacteria?

Attachment to host
Attachment to related bacteria


What happens when you treat a gram negative bacteria with EDTA and lysozyme? Can this event be reversed?

You create a spheroplast - A cell wall deficient bacteria
If the whole cell wall is not removed, the cell wall can regenerate


What are the 3 components of LPS?

O side chain sugars
Core polysaccharide
Lipid A