Exam (elaborations)
USMLE Step 1 Exam Prep Questions And Answers ()
- Course
- Institution
USMLE Step 1 Exam Prep Questions And Answers ()
[Show more]
Seller
Follow
Content preview
USMLE STEP 1 Microbiology Exam Prep Questions And Answers(202472025)
What is a special cellular component of fungal membrane targeted in anti-fungal
medication? - ✔✔Ergosterol
A major sterol
What is the special component of bacterial cell wall? - ✔✔Peptidoglycan
Where are the normal flora found? Contributions to health? Causes of infection? -
✔✔Location:
- found on body surfaces contiguous with outside environment (GI, etc.)
- Semipermanent (dependent on life-changes)
Contributions to health:
- Protective functions by maintaining a certain pH other microorganisms cannot
proliferate
- Nutritional: synthesizing vitamin K + B
Causes of infection:
- "Getting lost" (E. coli to urethra causing UTI)
- Overgrowth due to immunocompromised state
Are there normal flora in the blood or organs? - ✔✔No
Sterile environment
,What is a medically important normal flora found in the nose? - ✔✔Staphylococcus
aureus
What are the pathogenicity mechanisms? (8) - ✔✔1. Colonization (adherence)
2. Avoiding immediate destruction by host defense sys.
3. "Hunting + Gathering" needed nutrients
4. Antigenic variation
5. Ability to survive intracellularly
6. Type III secretion systems
7. Inflammation of Immune-mediated damage
8. Physical damage
What are the types of colonization? - ✔✔1. Adherence to cell surface
- *Pili*/fimbriae: primary mechanism in most G- bacteria (E. coli)
- Teichoic acids: G+ bacteria (acts as an antigenic determinant)
- Adhesins
- IgA proteases
2. Partial adherence
- biofilms (S. epidermidis, S. mutans)
(Biofilms are densely packed microorganisms forming a protective 'film' by doing
so; "cops standing outside of general admission; cannot get to people within general
admission area doing illegal things")
What are the types of mechanism used in avoiding immediate destruction by host
defense system? - ✔✔1. Anti-phagocytic surface components (inhibit
phagocytosis):
- *Capsules*/slim layers: "bar of soap slippery"
,kj: "Some Killers Have Pretty Nice Capsules Bro"
S: Streptococcus pneumoniae
K: Klebsiella penumoniae
H: Haemophilus influenzae type B
P: Pseudomonas aeruginosa
N: Neisseria meningitidis
C: Cryptococcus neoformans
B: Bordetella pertussis
- Streptococcus pyogenes: M protein
- Neisseria gonorrhoeae: Pili
- Staphylococcus aureus: A protein (binds IgG-Fc portion)
"MAP"
2. IgA proteases
3. Siderophores: steal (chelate) iron
What are antigenic variation mechanisms and microorganisms? - ✔✔- Changing
surface antigens to avoid immune destruction
- N. gonorrhoeae: pili + outer membrane proteins
- Trypanosoma brucei rhodesiense + T. b. gambiense: phase variation
- Enterobacteria: capsular and flagellar antigens may or may not be expressed
, What are bacteria with abilities to survive intracellularly (obligate/facultative)? -
✔✔kj: "Listen Sally Yer Friend Bruce Must Leave" (Facultative Intracellular bugs)
List: Listeria
Sal: Salmonella
Yer: Yersinia
Fr: Francisella
Bruce: Brucella
M: Mycobacterium tuberculosis
Le: Legionella
Obligate intracellular: "stay inside cells when its Really Chilly and Cold" (Can't
make own ATP)
R: Rickettsia
C: Chlamydia
C:Coxiella
1. Evading intracellular killing by professional phagocytic cells: allows intracellular
growth
- M. tuberculosis: inhibiting phagosome-lysosome fusion (slime layer)
- Listeria: escapes phagosome into the cytoplasm before phagosome-lysosome
fusion (rocket-shooting cell to cell)
2. Invasins: ability to invade non-phagocytic cells
- Yersinia pseudotuberculosis (causing diarrhea)
What happens when intracellular organisms escape macrophage phagocytosis? -
✔✔Macrophages "block" in the microorganism forming *granulomas*
What is the type III secretion system? - ✔✔Ability found in many pathogens
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller manassehtaliban95. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $13.44. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
75323 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now