BIO205
Microbiology
Latest Final Exam Review
(With Solutions)
2026
1
,1. Case: A patient with a prosthetic heart valve develops fever and
positive blood cultures for Staphylococcus epidermidis.
Question: Which virulence factor most contributes to this infection?
- A. Exotoxin A
- B. Biofilm formation
- C. Capsule polysaccharide
- D. Hemolysin
Answer: B. Biofilm formation
Rationale: S. epidermidis adheres to prosthetic material and produces
biofilm, protecting bacteria from host immunity and antibiotics.
---
2. Case: A nurse is caring for a patient with watery diarrhea after broad-
spectrum antibiotics.
Question: Which diagnostic test is most appropriate?
- A. Blood culture
- B. Stool culture for Salmonella
- C. ELISA for Clostridioides difficile toxins
- D. Urine culture
Answer: C. ELISA for C. difficile toxins
Rationale: Antibiotic-associated diarrhea is commonly due to C. difficile;
toxin detection confirms diagnosis.
---
3. Case: A patient presents with meningitis. Gram stain shows Gram-
negative diplococci.
Question: Which organism is most likely?
- A. Neisseria meningitidis
- B. Haemophilus influenzae
- C. Streptococcus pneumoniae
- D. Listeria monocytogenes
2
, Answer: A. Neisseria meningitidis
Rationale: Gram-negative diplococci in CSF strongly suggest N.
meningitidis.
---
4. Case: A burn patient develops greenish wound exudate with fruity
odor.
Question: Which pathogen is implicated?
- A. Pseudomonas aeruginosa
- B. Klebsiella pneumoniae
- C. Proteus mirabilis
- D. Enterococcus faecalis
Answer: A. Pseudomonas aeruginosa
Rationale: Pseudomonas produces pyocyanin pigment and
characteristic odor.
---
5. Case: A patient with HIV presents with pneumonia. Bronchoalveolar
lavage shows cysts stained with silver stain.
Question: Which organism is most likely?
- A. Pneumocystis jirovecii
- B. Candida albicans
- C. Aspergillus fumigatus
- D. Cryptococcus neoformans
Answer: A. Pneumocystis jirovecii
Rationale: Silver stain highlights cysts of P. jirovecii, common in
immunocompromised patients.
---
6. Case: A patient develops sepsis after urinary catheterization.
Question: Which organism is most commonly implicated?
- A. E. coli
3
Microbiology
Latest Final Exam Review
(With Solutions)
2026
1
,1. Case: A patient with a prosthetic heart valve develops fever and
positive blood cultures for Staphylococcus epidermidis.
Question: Which virulence factor most contributes to this infection?
- A. Exotoxin A
- B. Biofilm formation
- C. Capsule polysaccharide
- D. Hemolysin
Answer: B. Biofilm formation
Rationale: S. epidermidis adheres to prosthetic material and produces
biofilm, protecting bacteria from host immunity and antibiotics.
---
2. Case: A nurse is caring for a patient with watery diarrhea after broad-
spectrum antibiotics.
Question: Which diagnostic test is most appropriate?
- A. Blood culture
- B. Stool culture for Salmonella
- C. ELISA for Clostridioides difficile toxins
- D. Urine culture
Answer: C. ELISA for C. difficile toxins
Rationale: Antibiotic-associated diarrhea is commonly due to C. difficile;
toxin detection confirms diagnosis.
---
3. Case: A patient presents with meningitis. Gram stain shows Gram-
negative diplococci.
Question: Which organism is most likely?
- A. Neisseria meningitidis
- B. Haemophilus influenzae
- C. Streptococcus pneumoniae
- D. Listeria monocytogenes
2
, Answer: A. Neisseria meningitidis
Rationale: Gram-negative diplococci in CSF strongly suggest N.
meningitidis.
---
4. Case: A burn patient develops greenish wound exudate with fruity
odor.
Question: Which pathogen is implicated?
- A. Pseudomonas aeruginosa
- B. Klebsiella pneumoniae
- C. Proteus mirabilis
- D. Enterococcus faecalis
Answer: A. Pseudomonas aeruginosa
Rationale: Pseudomonas produces pyocyanin pigment and
characteristic odor.
---
5. Case: A patient with HIV presents with pneumonia. Bronchoalveolar
lavage shows cysts stained with silver stain.
Question: Which organism is most likely?
- A. Pneumocystis jirovecii
- B. Candida albicans
- C. Aspergillus fumigatus
- D. Cryptococcus neoformans
Answer: A. Pneumocystis jirovecii
Rationale: Silver stain highlights cysts of P. jirovecii, common in
immunocompromised patients.
---
6. Case: A patient develops sepsis after urinary catheterization.
Question: Which organism is most commonly implicated?
- A. E. coli
3
