Exam 1a. Flashcards
(98 cards)
Host defenses against encapsulated bacteria
- Skin and Mucus membranes
- White Blood Cells (Neutrophils and Lymphocytes)
- Immunoglobulins
- Complement
- Cytokines and other acute phase reactants
- The Spleen
How does the polysaccharide capsule protect the bacteria
inhibits phagocytosis of the organism
how do pili protect the bacteria
Promotes attachment of the organism to mucosal surface
Where is the polysaccharide capsule?
around all the outer cellular material
Pathogensis: bacteria goes into the epithelium, then it can cross the blood-brain barrier, and can cause local infections like p. meningitis
Streptococcus pneumoniae
What part of the immune system is designed to recognize polysaccharide capsule antigens?
Marginal zone B cells
- children don’t have good B cell immunity until 2+y/o
does the innate immune system protect against encapsulated organisms
yes, we make antibodies during colonization or infection- basis for vaccines
What are the encapsulated organisms
- Neisseria meningitidis
- Neisseria gonorrhea
- Streptococcus pneumoniae
- Haemophilus influenzae
What type of bacteria is Neisseria meningitidis
aerobic gram negative diplocccus**
encapsulated
Diseases caused by Neisseria meningitidis
- Meningococcemia (bacteremia) *more dangerous
- Meningococcal meningitis
Virulence factors of N. meningiditis
potent endotoxin
Neisseria meningitidis reservoir
young adults
Sx of Neisseria meningitidis
purpura and petechiae rash that is non-blanching
-rash may become subcutaneous bleeding and necrotic
when do we give the meningococcal vaccine
age 11-12, booser at 16 routinely or
>2 months if increased risk of disease (adolescents, immune disorder*, occupational exposure, travel exposure
pathogensis: -Exposure to colonized adult
- Acquisition of organism in nasopharynx
- Asymptomatic carriage, then immunity and colonization for 2-4 months OR Colonization which can result in Bacteremia and/or Meningitis
Neisseria meningitidis
HibMenCY, MCV4-D, MCV4-CRM, MPSV4, MenB-4C and MenB-FHbp are vaccines to protect against
Meningococcal
**choice of vaccine depends on age
Gram negative kidney bean shaped diplococci
Neisseria gonorrhea
Not encapsulated but has lipopolysaccharide
Neisseria gonorrhea
What can Neisseria gonorrhea be grown on
Chocolate agar/ carbon dioxide
Neisseria gonorrhea: oxidase +/-? and Catalse +/-?
+, +
When is it important speciate Neisseria gonorrhea
when found in children because it could indicate sexual abuse
**isolate using 2 methods in children
What does Neisseria gonorrhea ferment?
glucose
How can you identify/speciating Neisseria gonorrhea in the lab?
- sugar fermentation
- enzymatic
- fluorescent antibody
- Nucleic amplication (NAAT)***
Virulence characteristics of Neisseria gonorrhea
- pili
- outer membrane proteins
- ability to use iron
- IgA protease
- LPS
- cell wall peptidoglycan