1 | Page
USMLE TEST BANK Step 1
Microbiology 2026 | Medical School Exam
Prep | Verified Questions & Answers |
Student-Approved Real Exam Resource
What is a special cellular component of fungal membrane targeted in
anti-fungal medication? -- Verified--Solution----Ergosterol
A major sterol
What is the special component of bacterial cell wall? -- Verified--
Solution----Peptidoglycan
Where are the normal flora found? Contributions to health? Causes of
infection? -- Verified--Solution----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
,2 | Page
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? -- Verified--Solution----
No
Sterile environment
What is a medically important normal flora found in the nose? --
Verified--Solution----Staphylococcus aureus
What are the pathogenicity mechanisms? (8) -- Verified--Solution----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? -- Verified--Solution----1.
Adherence to cell surface
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- *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? -- Verified--Solution----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
, 4 | Page
- 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? --
Verified--Solution----- 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)? -- Verified--Solution----kj: "Listen Sally Yer
Friend Bruce Must Leave" (Facultative Intracellular bugs)
List: Listeria
Sal: Salmonella
USMLE TEST BANK Step 1
Microbiology 2026 | Medical School Exam
Prep | Verified Questions & Answers |
Student-Approved Real Exam Resource
What is a special cellular component of fungal membrane targeted in
anti-fungal medication? -- Verified--Solution----Ergosterol
A major sterol
What is the special component of bacterial cell wall? -- Verified--
Solution----Peptidoglycan
Where are the normal flora found? Contributions to health? Causes of
infection? -- Verified--Solution----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
,2 | Page
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? -- Verified--Solution----
No
Sterile environment
What is a medically important normal flora found in the nose? --
Verified--Solution----Staphylococcus aureus
What are the pathogenicity mechanisms? (8) -- Verified--Solution----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? -- Verified--Solution----1.
Adherence to cell surface
,3 | Page
- *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? -- Verified--Solution----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
, 4 | Page
- 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? --
Verified--Solution----- 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)? -- Verified--Solution----kj: "Listen Sally Yer
Friend Bruce Must Leave" (Facultative Intracellular bugs)
List: Listeria
Sal: Salmonella
