FREE ASCP Technologist in Microbiology Questions and Answers

Question 1

Which culture media are commonly used to cultivate different species of Mycobacterium?

Accepted Answer

Lowenstein-Jensen and Middlebrook agar

Answer

Lowenstein-Jensen (LJ) agar and Middlebrook agar are specialized culture media specifically formulated for the isolation and growth of Mycobacterium species, including Mycobacterium tuberculosis. LJ agar is an egg-based medium that inhibits other bacteria, while Middlebrook agars (e.g., 7H10, 7H11) are synthetic agar-based media. Both provide the necessary nutrients and conditions for the slow-growing mycobacteria to thrive, making them essential for diagnosing mycobacterial infections.

Question 2

In the Laboratory Response Network for Biological Threats, sentinel laboratories play which of the following roles?

Accepted Answer

Perform regular diagnostic procedures and determine if samples need to be sent somewhere else for additional testing.

Answer

Sentinel laboratories are the first line of defense in the Laboratory Response Network (LRN) for biological threats. Their primary role is to perform routine diagnostic testing on clinical samples. If a sample exhibits characteristics suspicious for a high-consequence biological agent, sentinel laboratories are responsible for ruling out common pathogens and then referring the sample to a higher-level LRN laboratory for definitive identification and advanced testing.

Question 3

Which antibiotic, by binding to D-alanyl D-alanine, inhibits the formation of peptidoglycans and hence inhibits the growth of bacteria?

Accepted Answer

Vancomycin

Answer

Vancomycin is a glycopeptide antibiotic that inhibits bacterial cell wall synthesis, primarily in Gram-positive bacteria. It achieves this by binding specifically to the D-alanyl-D-alanine termini of peptidoglycan precursors. This binding prevents the transpeptidation and transglycosylation reactions necessary for cross-linking the peptidoglycan chains, thereby disrupting cell wall formation and inhibiting bacterial growth.

Question 4

Since hyphae exhibit _____ between the yeast cell and the hyphae or pseudohyphae, they can be identified from germ tubes.

Accepted Answer

constriction or septa

Answer

Germ tubes are true outgrowths of yeast cells, typically observed in Candida albicans, and are characterized by a lack of constriction at their base where they emerge from the parent cell. In contrast, true hyphae or pseudohyphae exhibit a visible constriction or septa (cross-walls) at the point of budding from the yeast cell or other hyphal segments. This morphological difference is a key diagnostic feature for distinguishing C. albicans germ tubes.

Question 5

A throat swab was obtained from an individual who appeared to have thrush. Which of the following would make it possible to distinguish Candida albicans from other Candida species?

Accepted Answer

Pagano-Levin agar

Answer

Pagano-Levin agar is a differential culture medium specifically designed to distinguish Candida albicans from other Candida species. It contains tetrazolium salts that are reduced by C. albicans, resulting in the formation of distinctive pink or red colonies. Other Candida species typically produce white or cream-colored colonies, allowing for presumptive identification of C. albicans in clinical samples, such as throat swabs from thrush patients.

ASCP Phlebotomy Technician Exam Practice Test

ASCP Phlebotomy Technician Exam Practice Test

FREE ASCP Technologist in Microbiology Questions and Answers