Medical Laboratory Technician Exam FREE Medical Laboratory Technician Clinical Microbiology Questions and Answers 3

Question 1

A CSF Gram stain from a neonate reveals Gram-positive short rods. Which organism should be suspected and what confirmatory test is characteristic?

Accepted Answer

Listeria monocytogenes confirmed by tumbling motility at 25 degrees C

Answer

Listeria monocytogenes is a Gram-positive rod that causes neonatal meningitis and demonstrates characteristic tumbling motility when grown at room temperature.

Question 2

Which selective and differential medium is used to isolate Neisseria gonorrhoeae from specimens containing mixed flora?

Accepted Answer

Modified Thayer-Martin agar

Answer

Modified Thayer-Martin agar contains vancomycin, colistin, nystatin, and trimethoprim to suppress normal flora while supporting growth of pathogenic Neisseria.

Question 3

An anaerobic blood culture grows Gram-positive rods that produce a double zone of hemolysis on blood agar. What is the most likely organism?

Accepted Answer

Clostridium perfringens

Answer

Clostridium perfringens characteristically produces a double zone of hemolysis due to alpha and theta toxins and is associated with gas gangrene.

Question 4

A sputum culture from an immunocompromised patient grows a mucoid, non-lactose-fermenting Gram-negative rod that produces a grape-like odor and is oxidase-positive. Which organism is identified?

Accepted Answer

Pseudomonas aeruginosa

Answer

Pseudomonas aeruginosa is an oxidase-positive, non-lactose-fermenting Gram-negative rod known for its grape-like odor and production of blue-green pigments.

Question 5

Which fungal organism appears as large, broad-based budding yeast cells in a KOH preparation of lung tissue from a patient in the Ohio River Valley?

Accepted Answer

Blastomyces dermatitidis

Answer

Blastomyces dermatitidis produces large thick-walled yeast with characteristic broad-based buds and is endemic to the Ohio and Mississippi River valleys.

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Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam FREE Medical Laboratory Technician Clinical Microbiology Questions and Answers 3