QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS lOMoARcPSD| 69811638
UAMS MICROBIOLOGY FINAL
QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS ALREADY
PASSED LATEST UPDATED 2026/2027
Gram-Positive Cocci Differentiation Matrix (Multiple Choice)
Question 1: A Gram-positive coccus produces a black precipitate on Bile
Esculin Agar (BEA), grows in 6.5% NaCl broth, and is Optochin-resistant.
What is the organism?
A. Streptococcus pneumoniae
B. Group D Streptococcus (non-enterococcus)
C. Enterococcus species
D. Viridans Group Streptococci
✔✔ Correct Answer: C
Question 2: An organism tests positive (black) on Bile Esculin Agar, fails
to grow in 6.5% NaCl broth, and exhibits Optochin resistance. Which
organism does this profile indicate?
A. Enterococcus faecalis
B. Group D Streptococcus (e.g., Streptococcus bovis)
C. Streptococcus pyogenes
D. Streptococcus pneumoniae
✔✔ Correct Answer: B
)
, QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS lOMoARcPSD| 69811638
Question 3: A catalase-negative, alpha-hemolytic Gram-positive coccus is
negative (colorless) on Bile Esculin Agar, negative for 6.5% salt tolerance,
and exhibits a clear zone of inhibition around an Optochin (P) disk. What
is the identification?
A. Viridans Group Streptococci
B. Group D Streptococcus
C. Enterococcus faecium
D. Streptococcus pneumoniae
✔✔ Correct Answer: D
Question 4: Which organism is characterized by a colorless BEA slant, no
growth in 6.5% NaCl broth, and resistance to Optochin?
A. Streptococcus pneumoniae
B. Viridans Group Streptococci
C. Enterococcus species
D. Group D Streptococcus
✔✔ Correct Answer: B
Hemolysis: Beta
Gram Stain: GP Coccobacilli
Catalase: +
BEA: +
CAMP/Hippurate: +
Motility: + @ 25 C -ANSWER✔✔Listeria
)
, QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS lOMoARcPSD| 69811638
What organisms are motile at 25 C? -ANSWER✔✔Yersinia entercolitica
& Listeria
What GPR organisms form spores? -ANSWER✔✔Bacillus species
(aerobic)
Clostridium species (anaerobic)
What temperature should CIN agar be incubated at? -ANSWER✔✔RT
Selective for Gram-Negative Bacilli -ANSWER✔✔EMB & MAC
Selective media for Gram-positive organisms -ANSWER✔✔CNA & PEA
Gram staining steps -ANSWER✔✔1. crystal violet
2. iodine
3. alcohol
4. safranin
ID Of Staphylococci -ANSWER✔✔-Slide coagulase
-Tube coagulase
-MSA
-Latex agglutination
-Novobiocin
Reagent: Bile Solubility -ANSWER✔✔10% deoxycholate (bile)
Enhance growth of specific MOs, while inhibiting the growth of others
(GN & Selenite) -ANSWER✔✔Enrichment Broths
No antimicrobial substances & allows growth of most organisms (BAP,
CHOC) -ANSWER✔✔Nonselective Media
)
UAMS MICROBIOLOGY FINAL
QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS ALREADY
PASSED LATEST UPDATED 2026/2027
Gram-Positive Cocci Differentiation Matrix (Multiple Choice)
Question 1: A Gram-positive coccus produces a black precipitate on Bile
Esculin Agar (BEA), grows in 6.5% NaCl broth, and is Optochin-resistant.
What is the organism?
A. Streptococcus pneumoniae
B. Group D Streptococcus (non-enterococcus)
C. Enterococcus species
D. Viridans Group Streptococci
✔✔ Correct Answer: C
Question 2: An organism tests positive (black) on Bile Esculin Agar, fails
to grow in 6.5% NaCl broth, and exhibits Optochin resistance. Which
organism does this profile indicate?
A. Enterococcus faecalis
B. Group D Streptococcus (e.g., Streptococcus bovis)
C. Streptococcus pyogenes
D. Streptococcus pneumoniae
✔✔ Correct Answer: B
)
, QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS lOMoARcPSD| 69811638
Question 3: A catalase-negative, alpha-hemolytic Gram-positive coccus is
negative (colorless) on Bile Esculin Agar, negative for 6.5% salt tolerance,
and exhibits a clear zone of inhibition around an Optochin (P) disk. What
is the identification?
A. Viridans Group Streptococci
B. Group D Streptococcus
C. Enterococcus faecium
D. Streptococcus pneumoniae
✔✔ Correct Answer: D
Question 4: Which organism is characterized by a colorless BEA slant, no
growth in 6.5% NaCl broth, and resistance to Optochin?
A. Streptococcus pneumoniae
B. Viridans Group Streptococci
C. Enterococcus species
D. Group D Streptococcus
✔✔ Correct Answer: B
Hemolysis: Beta
Gram Stain: GP Coccobacilli
Catalase: +
BEA: +
CAMP/Hippurate: +
Motility: + @ 25 C -ANSWER✔✔Listeria
)
, QUESTIONS AND ANSWERS WITH COMPLETE SOLUTIONS lOMoARcPSD| 69811638
What organisms are motile at 25 C? -ANSWER✔✔Yersinia entercolitica
& Listeria
What GPR organisms form spores? -ANSWER✔✔Bacillus species
(aerobic)
Clostridium species (anaerobic)
What temperature should CIN agar be incubated at? -ANSWER✔✔RT
Selective for Gram-Negative Bacilli -ANSWER✔✔EMB & MAC
Selective media for Gram-positive organisms -ANSWER✔✔CNA & PEA
Gram staining steps -ANSWER✔✔1. crystal violet
2. iodine
3. alcohol
4. safranin
ID Of Staphylococci -ANSWER✔✔-Slide coagulase
-Tube coagulase
-MSA
-Latex agglutination
-Novobiocin
Reagent: Bile Solubility -ANSWER✔✔10% deoxycholate (bile)
Enhance growth of specific MOs, while inhibiting the growth of others
(GN & Selenite) -ANSWER✔✔Enrichment Broths
No antimicrobial substances & allows growth of most organisms (BAP,
CHOC) -ANSWER✔✔Nonselective Media
)
