ATI RN
microbiology chapter 1 test bank Questions
Question 1 of 5
A fecal sample cultured on Endo agar produced red, lactose-positive colonies. What microorganism is most likely present?
Correct Answer: A
Rationale: The correct answer is A: Escherichia coli. On Endo agar, lactose-fermenting bacteria produce red colonies due to acid production. Escherichersia coli is a lactose-fermenting, gram-negative bacillus commonly found in the intestines. Salmonella and Shigella are lactose-negative and do not produce red colonies on Endo agar. Proteus is also lactose-negative and doesn't typically grow on Endo agar.
Therefore, based on the lactose fermentation and colony color, Escherichia coli is the most likely microorganism present in the fecal sample.
Question 2 of 5
Detection of galactomannan and free mannan is used for diagnosing
Correct Answer: A
Rationale: The correct answer is A: aspergillosis and candidiasis. Detection of galactomannan and free mannan is commonly used in diagnosing these fungal infections. Galactomannan is a component of the cell wall of Aspergillus species, while free mannan is associated with Candida species. This detection method helps in identifying these specific fungal infections accurately.
B: Syphilis is caused by a bacterium, Treponema pallidum, and is not diagnosed using galactomannan or free mannan detection.
C: Leptospirosis is a bacterial infection caused by the Leptospira species and is not diagnosed using galactomannan or free mannan detection.
D: HIV infection is a viral infection caused by the human immunodeficiency virus and is not diagnosed using galactomannan or free mannan detection.
Question 3 of 5
Which of the following growth media is most suitable for isolation of Candida:
Correct Answer: C
Rationale:
Rationale:
1. Candida is a fungus commonly isolated from clinical specimens.
2. Sabouraud agar is the most suitable medium for Candida due to its low pH and high dextrose content.
3. Low pH inhibits bacterial growth, while dextrose promotes fungal growth.
4. Zeisler media, Chocolate agar, and Muller-Hinton agar are not specific for fungal isolation.
Summary:
- Zeisler media is used for anaerobic bacteria.
- Chocolate agar is used for fastidious organisms like Haemophilus.
- Muller-Hinton agar is for antibiotic susceptibility testing, not fungal isolation.
Question 4 of 5
A puncture sample taken from the lymph node of a patient with preliminary diagnosis of protozoan disease has been investigated. The preparation was processed with Giemsa stain and the following was detected: crescent-shaped bodies with pointed tips, blue cytoplasm and red nuclei. What protozoa have been detected in the preparation?
Correct Answer: D
Rationale: The correct answer is D: Viscerotropic Leishmania. The presence of crescent-shaped bodies with pointed tips, blue cytoplasm, and red nuclei is characteristic of Leishmania species. Viscerotropic Leishmania causes visceral leishmaniasis, also known as kala-azar, which affects the internal organs.
Toxoplasma typically presents as tachyzoites, not crescent-shaped bodies. Plasmodium malariae is a malaria parasite with different morphology. Dermatotropic Leishmania causes cutaneous leishmaniasis, not the visceral form indicated by the morphology described in the question.
Question 5 of 5
Legionella and Neisseria are examples of:
Correct Answer: B
Rationale: The correct answer is B: Legionella and Neisseria are both gram-negative aerobic rods and cocci. Legionella is a rod-shaped bacterium, while Neisseria is a diplococcus. Both are aerobic, meaning they require oxygen for growth. The other choices are incorrect because Legionella and Neisseria are not facultative anaerobes (
A), spirochetes (
C), or anaerobic cocci (
D). Understanding the characteristics of these bacteria helps in differentiating and selecting the correct answer.