UAMS MICROBIOLOGY CASE
DEVELOPMENT Study Set 2
(2026/27) – Complete Q&A with
Rationales
Ace your clinical microbiology assessments with the ultimate study companion
tailored specifically for the University of Arkansas for Medical Sciences (UAMS)
curriculum. This premium resource features actual case development questions, verified
answers, and comprehensive rationales designed to help you master complex
microbiological concepts and clinical scenarios.
Why Download This Study Set?
• 100% Aligned with the 2026 Syllabus: Contains the latest case-based clinical
updates, ensuring you are studying highly relevant material.
• Detailed Step-by-Step Rationales: Every answer includes an in-depth
breakdown explaining why a choice is correct and why others are incorrect,
reinforcing critical thinking.
• High-Yield Case Analysis: Focuses heavily on diagnostic test interpretation,
colony count metrics, biochemical identification (e.g., E. coli, Shigella,
Salmonella), and antimicrobial susceptibility testing rules.
Core Topics Covered
• Bacterial Identification & Biochemicals: Indole, Lysine, Lactose, Motility
profiles, and TSI reactions.
• Antimicrobial Susceptibility Testing (AST): Standardized parameters
including McFarland standards, Müller-Hinton agar guidelines, and incubation
requirements.
• Specimen & Urine Analysis: Colony count evaluation criteria (≥ 10⁵ CFU/mL
UTI indicators) and contamination tracking.
• Clinical Pathogen Profiles: Key diagnostic features for Staphylococcus aureus,
Streptococcus, Enterobacterales, and more.
1. Procedure for medicolegal cases when an isolate appears to be GC
Perform 2 different ID tests
Rationale: In medicolegal cases (such as suspected sexual assault),
1
, confirming Neisseria gonorrhoeae (GC) requires absolute legal and scientific
certainty. Because of potential cross-reactivity and social/legal implications,
guidelines dictate using two different diagnostic modalities based on distinct
principles (e.g., a nucleic acid amplification test [NAAT] combined with
confirmation via culture and biochemical/carbohydrate utilization tests like CTA
sugars or mass spectrometry).
2. Purpose of GN broth
Isolate specific GNR such as Salmonella and Shigella
Rationale: Gram-Negative (GN) broth is a selective enrichment medium
designed to temporarily suppress normal fecal flora (such as coliforms) while
permitting the selective multiplication of enteric pathogens like Salmonella spp.
and Shigella spp. during the early hours of incubation.
3. One organism with a colony count of 10^5 CFU/mL
Probable UTI
Rationale: A colony count of \(\ge 10^{5}\) colony-forming units per millilitre
(CFU/mL) of a single potential pathogen in a clean-catch urine sample
traditionally serves as the diagnostic threshold confirming a true, significant
urinary tract infection (UTI) rather than external urethral contamination.
4. Multiple organisms with equal colony counts
Probable Contaminant
Rationale: Finding multiple distinct bacterial species in roughly equal quantities
in a standard urine culture strongly points to contamination from the perineal
skin, vagina, or distal urethra during collection, rather than a genuine bladder
infection.
5. One organism with a colony count of 10^5 CFU/mL and one organism with
30 colonies
Probable UTI
Rationale: The presence of a single organism dominant at the \(\ge 10^{5}\)
2
, CFU/mL threshold fulfills clinical criteria for a UTI. The secondary organism with
a very low colony count (30 colonies equals \(3 \times 10^3\) or \(3 \times 10^4\)
CFU/mL depending on loop size) represents minor background urethral or
collection contamination.
6. Formula for calculating colony forming units
Number of colonies x calibration factor of loop (0.1mL = .01mL =
1000)
Rationale: To determine the concentration of bacteria per millilitre of urine, the
raw colony count must be multiplied by the reciprocal of the volume delivered by
the calibrated loop. If using a \(0.01\text{ mL}\) loop (\(1/100\text{ mL}\)), multiply
by \(100\); if using a \(0.001\text{ mL}\) loop (\(1/1000\text{ mL}\)), multiply by
\(1000\) to get the final CFU/mL count. (Note: The original text listed \(0.1\text{
mL}=100\), but typically standard calibrated urine loops are \(0.01\text{ mL}\) and
\(0.001\text{ mL}\).)
7. Clue cells
Vaginal cells with bacteria growing on them
Rationale: Clue cells are squamous vaginal epithelial cells whose membranes
have a fuzzy appearance because they are heavily covered with adherent
coccobacilli (primarily Gardnerella vaginalis). The margins of these epithelial cells
are completely obscured by the bacterial biofilm.
8. Disease associated with clue cells
Bacterial Vaginosis
Rationale: Bacterial Vaginosis (BV) is a dysbiosis characterized by a decrease
in protective, hydrogen-peroxide-producing Lactobacillus species and an
overgrowth of anaerobic options. Clue cells seen on a wet mount are a primary
diagnostic indicator under Amsel's criteria.
9. Organisms associated with bacterial vaginosis
Gram negative-Gram variable
3
DEVELOPMENT Study Set 2
(2026/27) – Complete Q&A with
Rationales
Ace your clinical microbiology assessments with the ultimate study companion
tailored specifically for the University of Arkansas for Medical Sciences (UAMS)
curriculum. This premium resource features actual case development questions, verified
answers, and comprehensive rationales designed to help you master complex
microbiological concepts and clinical scenarios.
Why Download This Study Set?
• 100% Aligned with the 2026 Syllabus: Contains the latest case-based clinical
updates, ensuring you are studying highly relevant material.
• Detailed Step-by-Step Rationales: Every answer includes an in-depth
breakdown explaining why a choice is correct and why others are incorrect,
reinforcing critical thinking.
• High-Yield Case Analysis: Focuses heavily on diagnostic test interpretation,
colony count metrics, biochemical identification (e.g., E. coli, Shigella,
Salmonella), and antimicrobial susceptibility testing rules.
Core Topics Covered
• Bacterial Identification & Biochemicals: Indole, Lysine, Lactose, Motility
profiles, and TSI reactions.
• Antimicrobial Susceptibility Testing (AST): Standardized parameters
including McFarland standards, Müller-Hinton agar guidelines, and incubation
requirements.
• Specimen & Urine Analysis: Colony count evaluation criteria (≥ 10⁵ CFU/mL
UTI indicators) and contamination tracking.
• Clinical Pathogen Profiles: Key diagnostic features for Staphylococcus aureus,
Streptococcus, Enterobacterales, and more.
1. Procedure for medicolegal cases when an isolate appears to be GC
Perform 2 different ID tests
Rationale: In medicolegal cases (such as suspected sexual assault),
1
, confirming Neisseria gonorrhoeae (GC) requires absolute legal and scientific
certainty. Because of potential cross-reactivity and social/legal implications,
guidelines dictate using two different diagnostic modalities based on distinct
principles (e.g., a nucleic acid amplification test [NAAT] combined with
confirmation via culture and biochemical/carbohydrate utilization tests like CTA
sugars or mass spectrometry).
2. Purpose of GN broth
Isolate specific GNR such as Salmonella and Shigella
Rationale: Gram-Negative (GN) broth is a selective enrichment medium
designed to temporarily suppress normal fecal flora (such as coliforms) while
permitting the selective multiplication of enteric pathogens like Salmonella spp.
and Shigella spp. during the early hours of incubation.
3. One organism with a colony count of 10^5 CFU/mL
Probable UTI
Rationale: A colony count of \(\ge 10^{5}\) colony-forming units per millilitre
(CFU/mL) of a single potential pathogen in a clean-catch urine sample
traditionally serves as the diagnostic threshold confirming a true, significant
urinary tract infection (UTI) rather than external urethral contamination.
4. Multiple organisms with equal colony counts
Probable Contaminant
Rationale: Finding multiple distinct bacterial species in roughly equal quantities
in a standard urine culture strongly points to contamination from the perineal
skin, vagina, or distal urethra during collection, rather than a genuine bladder
infection.
5. One organism with a colony count of 10^5 CFU/mL and one organism with
30 colonies
Probable UTI
Rationale: The presence of a single organism dominant at the \(\ge 10^{5}\)
2
, CFU/mL threshold fulfills clinical criteria for a UTI. The secondary organism with
a very low colony count (30 colonies equals \(3 \times 10^3\) or \(3 \times 10^4\)
CFU/mL depending on loop size) represents minor background urethral or
collection contamination.
6. Formula for calculating colony forming units
Number of colonies x calibration factor of loop (0.1mL = .01mL =
1000)
Rationale: To determine the concentration of bacteria per millilitre of urine, the
raw colony count must be multiplied by the reciprocal of the volume delivered by
the calibrated loop. If using a \(0.01\text{ mL}\) loop (\(1/100\text{ mL}\)), multiply
by \(100\); if using a \(0.001\text{ mL}\) loop (\(1/1000\text{ mL}\)), multiply by
\(1000\) to get the final CFU/mL count. (Note: The original text listed \(0.1\text{
mL}=100\), but typically standard calibrated urine loops are \(0.01\text{ mL}\) and
\(0.001\text{ mL}\).)
7. Clue cells
Vaginal cells with bacteria growing on them
Rationale: Clue cells are squamous vaginal epithelial cells whose membranes
have a fuzzy appearance because they are heavily covered with adherent
coccobacilli (primarily Gardnerella vaginalis). The margins of these epithelial cells
are completely obscured by the bacterial biofilm.
8. Disease associated with clue cells
Bacterial Vaginosis
Rationale: Bacterial Vaginosis (BV) is a dysbiosis characterized by a decrease
in protective, hydrogen-peroxide-producing Lactobacillus species and an
overgrowth of anaerobic options. Clue cells seen on a wet mount are a primary
diagnostic indicator under Amsel's criteria.
9. Organisms associated with bacterial vaginosis
Gram negative-Gram variable
3
