Flashcards in Test q's Deck (132)
How does meningococci enter the blood?
from the pharynx- via pilus-mediated adherence to and penetration of the mucosal epithelium
What is n meningitidis' virulence factor?
- sex pilus
- produces an IgA protease that facilitates survival by destroying antibodies
sputum gram stain shows many neutrophils but few or no organisms
very high fever in a smoker with diarrhea, confusion, and cough
Why cant legionella gram stain?
bc they have unique lipopolysaccharide chains on the outer membrane that inhibit gram staining
What is staph aureus' virulence factor that is bound to the peptidoglycan wall?
Protein A: binds to the Fc portion of IgG at the complement binding site thus preventing activation of complement
= decreased opsonization
What substance is SECRETED by staph?
Hemolysin: can produce hemolysis and destruction of neutrophils, macs, and platelets
Which bacteria have the ability to take up free DNA from the environment (transformation)
What bacteria are responsible for secondary bacterial pneumonia?
1. Strep pneumo
2. Staph aureus
3. H influenzae
What organism has a lipooligosaccharide
What is significant about N meningitidis' LOS?
1. It correlates with the outcome of the disease
2. It causes sepsis by induction of inflammatory response (interacts with toll like receptor 4)
3. Cause of cutaneous petechiae and hemorrhagic bullae
4. Causes Waterhouse-Friderichsen syndrome
What is the major virulence factor of Group A strep?
Protein M: inhibits phagocytosis and inactivates complement
Streptolysin O MOA?
- found on group A strep- strep pyogenes
- lyses erythrocytes and PMNs but does not convey resistance to phagocytosis
budding yeast with a thick capsule
What does the DPT vaccine target?
the binding component (B subunit) of Diptheria's exotoxin
- antibody binding prevents the exotoxin from attaching to host cell membrane and preventing disease
In a pt with bronchial asthma and CBC with eosinophilia, what do you suspect?
- Allergic Bronchopulmonary Aspergillus
- seen in steroid dependent asthmatics
How does typhoid fever cause death?
- causes inflammation within Peyer's patches leading to intestinal hemorrhage and gut perforation
- polymicrobial peritonitis and sepsis
Pt presents with abdominal cramping, low fever, constipation and salmon colored rose spots on the abdomen, plus hepatosplenomegaly
What do the different HIV structural genes encode:
1. Gag = nucleocapsid proteins p24 & p7
2. Pol = reverse transciptase
3. Env = envelope glycoproteins ie gp120 and gp41
What is the only gram + bug with an endotoxin?
Stain with carbolfuschin = what bugs?
Acid fast stain = Ziehl neelsen: Nocardia and Mycobacteria
mucicarmine = ?
Cryptococus, stains the thick polysaccharid capsule red
Catalase positive organisms?
What are the conjugated vaccines and why are they conjugated?
for capsular antigens- a protein is conjugated to the polysaccharide antigen to promote T cell activation and subsequent class switching- a polysaccharide antigen alone cannot be presented to T cells (only IgM would be produced)
ex) H influenza type B and Meningococcal
What are the urease positive bugs?
2. H pylori
7. Staph epidermidis
8. Staph saprophyticus
Protein A: who has it and what does it do?
- Binds to Fc portion of Ig, prevents opsonization and phagocytosis
IgA protease: who has it and what does it do?
- enzyme that cleaves IgA in hinge region, secreted by SHiN: s pneumo, h influ, neisseria
- used to colonize resp mucosa
M protein: who has it and what does it d?
- Group A strep
- prevents phagocytosis