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CLS Clinical Microbiology and Immunology Flashcards

6 cards from real CLS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 6 CLS Clinical Microbiology and Immunology flashcards as text

  1. Which culture medium is required for growth of Haemophilus influenzae because it supplies both X factor (hemin) and V factor (NAD)?

    Answer: Chocolate agar

    Chocolate agar is made by heating blood to 80°C, which lyses red cells and releases X factor (hemin) and V factor (NAD), both required by Haemophilus influenzae.

  2. What is the fundamental principle of the ELISA (Enzyme-Linked Immunosorbent Assay)?

    Answer: Enzyme-conjugated antibodies generate a measurable color change upon antigen binding

    ELISA uses enzyme-labeled antibodies; after binding to the target antigen-antibody complex, the enzyme converts a colorless substrate to a colored product for quantification.

  3. Which fungal species produces germ tubes within 2–3 hours when incubated in human serum at 37°C?

    Answer: Candida albicans

    Candida albicans is presumptively identified by the germ tube test; formation of germ tubes in serum at 37°C within 3 hours is highly specific for this species.

  4. In the Kirby-Bauer disk diffusion method for antibiotic susceptibility testing, what parameter is measured?

    Answer: Diameter of the zone of inhibition around the antibiotic disk

    The Kirby-Bauer method measures the diameter of the clear zone of inhibition around antibiotic-impregnated disks placed on a lawn of bacteria on Mueller-Hinton agar.

  5. Which stain is used to detect acid-fast bacilli such as Mycobacterium tuberculosis in clinical specimens?

    Answer: Ziehl-Neelsen (acid-fast) stain

    The Ziehl-Neelsen stain uses carbol fuchsin dye that penetrates the mycolic acid-rich cell wall of acid-fast organisms; it resists decolorization with acid-alcohol, appearing red against a blue background.

  6. Which immunoglobulin class is the predominant antibody in mucosal secretions such as saliva, tears, colostrum, and breast milk?

    Answer: Secretory IgA (sIgA)

    Secretory IgA is the most abundant immunoglobulin in mucosal secretions; its dimeric form is stabilized by a secretory component that protects it from proteolytic degradation.