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UAMS Microbiology Exam 3 Practice Questions &
Answers (Verified Update)
This comprehensive study guide covers the core domains tested
on UAMS Microbiology Exam 3, aligned with the 2026–2027
curriculum. It includes original practice questions with detailed
rationales, organized by the core exam domains: Anaerobic
Bacteria, Mycobacteria, Fungi, Antimicrobial Agents &
Susceptibility Testing, Non-Fermentative Gram-Negative
Bacilli, Fastidious Gram-Negative Organisms, and Clinical
Microbiology Case Studies.
Exam Overview & Blueprint:
Parameter Details
Exam Format Multiple-choice, true/false, and case-based questions
Core Topics Anaerobes, mycobacteria, fungi, antimicrobial susceptibility, non-fermenters, fastidious organisms
Key Organisms Bacteroides, Clostridium, Mycobacterium, Candida, Aspergillus, Pseudomonas, Vibrio, Bordetella
Key Tests Anaerobic ID, Ziehl-Neelsen, KOH, germ tube, Kirby-Bauer, MIC, OF glucose
2026 Focus Case-based clinical scenarios, diagnostic test selection, antimicrobial resistance mechanisms
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Section 1: Anaerobic Bacteria )Q1. What is the primary
characteristic of anaerobic bacteria?
A) They require oxygen for growth
B) They grow only in the absence of oxygen
C) They grow in the presence of oxygen
D) They are always Gram-positive
Answer: B
Rationale: Anaerobic bacteria grow only in the absence of
oxygen. They lack the enzymes (superoxide dismutase, catalase)
needed to detoxify oxygen radicals .
Q2. How long should anaerobe jars/bags be held before reading
the plates?
A) 24 hours
B) 48 hours
C) 72 hours
D) 12 hours
Answer: B
Rationale: Anaerobe jars/bags should be held for 48 hours
before reading the plates to allow sufficient growth .
Q3. Which organism produces "molar tooth" colonies?
A) Actinomyces
B) Clostridium
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C) Bacteroides
D) Fusobacterium
Answer: A
Rationale: Actinomyces produces "molar tooth" colonies. It is
an anaerobic, branching Gram-positive bacillus .
Q4. Which organism produces sulfur granules?
A) Actinomyces
B) Clostridium perfringens
C) Bacteroides fragilis
D) Fusobacterium nucleatum
Answer: A
Rationale: Actinomyces produces sulfur granules, which are a
key diagnostic feature of actinomycosis .
Q5. What is the Gram stain of Actinomyces?
A) Gram-positive branching rods (filaments)
B) Gram-negative rods
C) Gram-positive cocci
D) Gram-negative cocci
Answer: A
Rationale: Actinomyces is a Gram-positive branching rod
(filamentous) organism. It is anaerobic .
Q6. What is the identification of the following organism: GNB,
anaerobe K, V, C & Bile = RBBE = black?
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A) Bacteroides fragilis
B) Fusobacterium nucleatum
C) Prevotella
D) Porphyromonas
Answer: A
Rationale: Bacteroides fragilis is identified as a Gram-negative
bacillus, anaerobe, resistant to K, V, C, and Bile, growing on
RBBE agar with black colonies .
Q7. Which organism produces a double zone of hemolysis?
A) Clostridium perfringens
B) Clostridium tetani
C) Clostridium botulinum
D) Clostridium difficile
Answer: A
Rationale: Clostridium perfringens produces a double zone of
hemolysis on blood agar .
Q8. What is the identification of the following organism: Double
zone of hemolysis, Reverse CAMP = +, lecithinase = +, Nagler =
+?
A) Clostridium perfringens
B) Clostridium tetani
C) Clostridium botulinum
D) Clostridium difficile
UAMS Microbiology Exam 3 Practice Questions &
Answers (Verified Update)
This comprehensive study guide covers the core domains tested
on UAMS Microbiology Exam 3, aligned with the 2026–2027
curriculum. It includes original practice questions with detailed
rationales, organized by the core exam domains: Anaerobic
Bacteria, Mycobacteria, Fungi, Antimicrobial Agents &
Susceptibility Testing, Non-Fermentative Gram-Negative
Bacilli, Fastidious Gram-Negative Organisms, and Clinical
Microbiology Case Studies.
Exam Overview & Blueprint:
Parameter Details
Exam Format Multiple-choice, true/false, and case-based questions
Core Topics Anaerobes, mycobacteria, fungi, antimicrobial susceptibility, non-fermenters, fastidious organisms
Key Organisms Bacteroides, Clostridium, Mycobacterium, Candida, Aspergillus, Pseudomonas, Vibrio, Bordetella
Key Tests Anaerobic ID, Ziehl-Neelsen, KOH, germ tube, Kirby-Bauer, MIC, OF glucose
2026 Focus Case-based clinical scenarios, diagnostic test selection, antimicrobial resistance mechanisms
, Page |2
Section 1: Anaerobic Bacteria )Q1. What is the primary
characteristic of anaerobic bacteria?
A) They require oxygen for growth
B) They grow only in the absence of oxygen
C) They grow in the presence of oxygen
D) They are always Gram-positive
Answer: B
Rationale: Anaerobic bacteria grow only in the absence of
oxygen. They lack the enzymes (superoxide dismutase, catalase)
needed to detoxify oxygen radicals .
Q2. How long should anaerobe jars/bags be held before reading
the plates?
A) 24 hours
B) 48 hours
C) 72 hours
D) 12 hours
Answer: B
Rationale: Anaerobe jars/bags should be held for 48 hours
before reading the plates to allow sufficient growth .
Q3. Which organism produces "molar tooth" colonies?
A) Actinomyces
B) Clostridium
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C) Bacteroides
D) Fusobacterium
Answer: A
Rationale: Actinomyces produces "molar tooth" colonies. It is
an anaerobic, branching Gram-positive bacillus .
Q4. Which organism produces sulfur granules?
A) Actinomyces
B) Clostridium perfringens
C) Bacteroides fragilis
D) Fusobacterium nucleatum
Answer: A
Rationale: Actinomyces produces sulfur granules, which are a
key diagnostic feature of actinomycosis .
Q5. What is the Gram stain of Actinomyces?
A) Gram-positive branching rods (filaments)
B) Gram-negative rods
C) Gram-positive cocci
D) Gram-negative cocci
Answer: A
Rationale: Actinomyces is a Gram-positive branching rod
(filamentous) organism. It is anaerobic .
Q6. What is the identification of the following organism: GNB,
anaerobe K, V, C & Bile = RBBE = black?
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A) Bacteroides fragilis
B) Fusobacterium nucleatum
C) Prevotella
D) Porphyromonas
Answer: A
Rationale: Bacteroides fragilis is identified as a Gram-negative
bacillus, anaerobe, resistant to K, V, C, and Bile, growing on
RBBE agar with black colonies .
Q7. Which organism produces a double zone of hemolysis?
A) Clostridium perfringens
B) Clostridium tetani
C) Clostridium botulinum
D) Clostridium difficile
Answer: A
Rationale: Clostridium perfringens produces a double zone of
hemolysis on blood agar .
Q8. What is the identification of the following organism: Double
zone of hemolysis, Reverse CAMP = +, lecithinase = +, Nagler =
+?
A) Clostridium perfringens
B) Clostridium tetani
C) Clostridium botulinum
D) Clostridium difficile
