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;
19 Cards in this Set
- Front
- Back
|
Describe the gram stain, oxidase, catalase, and oxygen requirements of members of the Neisseria genus
|
They are gram negative diplococci, obligate aerobes, catalase +, oxidase +
|
|
|
Where is Neisseria considered normal flora?
|
In the upper respiratory tract and other mucosal surfaces (unencapsulated strain)
|
|
|
What is needed to grow Neisseria in culture?
|
They need to be grown on chocolate agar with increased CO2
|
|
|
What are the major virulence factors for Neisseria meningitidus?
|
The major factor is the capsule, but they also contain endotoxin (LPS)
|
|
|
How do Neisseria meningitidus adhere to the epithelial surface?
|
They have fimbriae (pili) with adhesins
|
|
|
Describe the virulent capsule of Neisseria meningitidus
|
It is the major virulence factor and antiphagocytic; there are 13 serotypes with the most serious being A, B, C, Y and W135
|
|
|
What exoenzymes does Neisseria meningitidus secrete?
|
IgA protease
|
|
|
Describe the habitat of Neisseria meningitidus
|
It is only found in the human body (obligate parasite) on mucosal surfaces and may be present in the absence of disease (Carrier states)
|
|
|
How is Neisseria meningitidus transmitted?
|
From person to person via respiratory droplets, but it doesn't survive for long on surfaces/hands ect.; the carrier state is important in transmission
|
|
|
What groups are most susceptible to N. meningitidis infection, and what groups are "at risk"?
|
6-24mo, college students, and military recruits are most susceptible, while older children, teenagers, elderly and people with complement deficiencies are "at risk"
|
|
|
What are the three manifestations of meningococcus infection?
|
localized infection in the nasopharynx, meningococcemia, and meningitis
|
|
|
Describe the local infection of meningococcus
|
A person becomes colonized in the nasopharynx, mild inflammation occurs (URT infection or asymptomatic), and the person becomes a carrier if their immune response is good enough to keep the infection from becoming systemic
|
|
|
Describe meningococcemia
|
This occurs when the meningococcus spreads to the bloodstream via draining lymphatics resulting in sepsis, endotoxic shock, and DIC
|
|
|
What are some of the outcomes of meningococcmia?
|
Death commonly occurs as well as amputations and Waterhouse-Friderichsen syndrome (spread to adrenal gland)
|
|
|
Describe the meningitis associated with meningococcus
|
The bacteria spreads from the blood to the meninges via the choroid plexus and results in permanent brain damage; 80% fatal untreated, 10-15% fatal with appropriate therapy; onset is rapid!
|
|
|
What is the best way to diagnose an infection with Neisseria meningitidus?
|
Gram stain of the CSF to look for gram negative diplococci, neutrophils; culture is too slow
|
|
|
What is the new supportive therapy given to patients with DIC and septic shock?
|
activated protein C (Xigris) and steroids
|
|
|
What are the two vaccines for meningococcus and what groups are they for?
|
Menomune (MPSV4) is not for children under the age of 2; Menactra (MCV4) is approved for 11-12 year olds and particularly college students
|
|
|
What is the difference between menomune and menactra?
|
menomune is a purified capsule polysaccharide and menactra is a purified polysaccharide conjugated to a protein
|
