Medical Technologist Test Microbiology 3

Question 1

Which organism is identified by its characteristic 'safety pin' bipolar staining appearance?

Accepted Answer

Yersinia pestis

Answer

Yersinia pestis displays bipolar staining (safety pin appearance) with Wayson stain, a key feature for rapid presumptive identification.

Question 2

Obligate intracellular parasites that cause atypical pneumonia and cannot be grown on standard agar include which organism?

Accepted Answer

Chlamydophila pneumoniae

Answer

Chlamydophila pneumoniae is an obligate intracellular pathogen that requires host cell energy and cannot replicate on standard bacteriologic media.

Question 3

Which selective and differential medium is used to isolate Salmonella and Shigella from stool?

Accepted Answer

Hektoen enteric agar

Answer

Hektoen enteric (HE) agar differentiates Salmonella and Shigella from other gram-negatives by inhibiting coliforms and showing characteristic colony colors.

Question 4

The Quellung reaction (capsular swelling) is used to identify and serotype which organism?

Accepted Answer

Streptococcus pneumoniae

Answer

The Quellung reaction occurs when type-specific antibody binds the polysaccharide capsule of S. pneumoniae, making it appear swollen under microscopy.

Question 5

Which viral detection method directly identifies viral antigens in a patient specimen without culture?

Accepted Answer

Direct fluorescent antibody (DFA) test

Answer

DFA uses fluorescent-labeled antibodies to directly detect viral antigens in respiratory or other specimens within hours.

Medical Technologist Test Practice Test

Medical Technologist Test Practice Test

Medical Technologist Test Microbiology 3