Medical Laboratory Technician Exam FREE Medical Laboratory Technician Clinical Microbiology Questions and Answers 2

Question 1

A patient presents with watery diarrhea after recent antibiotic therapy. Which organism is most likely responsible and requires anaerobic culture on selective media?

Accepted Answer

Clostridioides difficile

Answer

C. difficile is the leading cause of antibiotic-associated diarrhea and is detected using anaerobic culture on cycloserine-cefoxitin-fructose agar or toxin assays.

Question 2

Which staining technique is most appropriate for identifying Mycobacterium tuberculosis in a sputum specimen?

Accepted Answer

Ziehl-Neelsen acid-fast stain

Answer

The Ziehl-Neelsen stain uses carbol fuchsin with heat to penetrate the waxy mycolic acid cell wall, rendering acid-fast bacilli red against a blue background.

Question 3

A urine culture grows greater than 100,000 CFU/mL of a Gram-negative rod that is lactose-positive on MacConkey agar and indole-positive. What is the most likely identification?

Accepted Answer

Escherichia coli

Answer

E. coli is the most common cause of urinary tract infections and characteristically ferments lactose and produces indole from tryptophan.

Question 4

Which atmospheric condition is required for primary isolation of Campylobacter jejuni from stool specimens?

Accepted Answer

Microaerophilic (5% O2, 10% CO2)

Answer

Campylobacter jejuni requires a microaerophilic environment with reduced oxygen and elevated CO2, typically incubated at 42 degrees C on selective media.

Question 5

A throat culture on sheep blood agar shows small translucent colonies surrounded by a clear zone of complete hemolysis. Which Lancefield group is most likely represented?

Accepted Answer

Group A (Streptococcus pyogenes)

Answer

Streptococcus pyogenes (Group A) produces beta-hemolysis on blood agar and is the primary pathogen sought in throat cultures for pharyngitis.

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam Practice Test

Medical Laboratory Technician Exam FREE Medical Laboratory Technician Clinical Microbiology Questions and Answers 2