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MLPAO Microbiology and Parasitology Diagnostic Methods Flashcards

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

Read the first 6 MLPAO Microbiology and Parasitology Diagnostic Methods flashcards as text

  1. Which automated system is commonly used for antimicrobial susceptibility testing and identification in Canadian laboratories?

    Answer: VITEK 2 or BD Phoenix automated systems

    VITEK 2 (bioMérieux) and BD Phoenix are widely used automated systems in Canadian laboratories for both organism identification and antimicrobial susceptibility testing. These systems use miniaturized biochemical reactions and MIC panels, providing results within 6-18 hours. They integrate with laboratory information systems for efficient workflow.

  2. What organism should be suspected when a laboratory worker observes small, gram-negative coccobacilli growing on chocolate agar but not on blood agar?

    Answer: Haemophilus influenzae

    Haemophilus influenzae requires both X factor (hemin) and V factor (NAD) for growth. Chocolate agar provides both factors through heated blood, while blood agar provides only X factor (V factor is not released from intact RBCs). This differential growth pattern is a key presumptive identification method.

  3. What is the trichrome stain used for in parasitology?

    Answer: Permanent staining of intestinal protozoan trophozoites and cysts in stool specimens

    The trichrome stain is a permanent stain for identifying intestinal protozoa (such as Entamoeba histolytica, Giardia lamblia, and Dientamoeba fragilis) in stool specimens preserved in polyvinyl alcohol (PVA) or SAF fixative. It provides excellent detail of nuclear and cytoplasmic features essential for accurate species identification.

  4. Which molecular test is used for rapid detection of Mycobacterium tuberculosis and rifampin resistance?

    Answer: GeneXpert MTB/RIF (Xpert)

    GeneXpert MTB/RIF is a rapid, cartridge-based NAAT that simultaneously detects M. tuberculosis complex and rifampin resistance within 2 hours directly from clinical specimens. It targets the rpoB gene and has revolutionized TB diagnosis globally. It is particularly valuable in Canadian settings for rapid diagnosis and public health response.

  5. What are the key differences between thick and thin blood smear examination for malaria diagnosis?

    Answer: Thick smears concentrate organisms for detection sensitivity; thin smears preserve morphology for species identification

    Thick smears lyse red blood cells and concentrate parasites, providing 10-20 times greater sensitivity for detecting malaria. Thin smears preserve red cell morphology and parasite structure, enabling species identification and parasitemia quantification. Both should be prepared and examined for optimal malaria diagnosis.

  6. Which bacterial pathogen produces a positive urease test within 4 hours and is associated with urinary tract stones?

    Answer: Proteus mirabilis

    Proteus mirabilis is a rapid urease producer that splits urea into ammonia and CO2, creating an alkaline urine that promotes struvite (magnesium ammonium phosphate) stone formation. It also characteristically swarms on blood agar and produces H2S on TSI. Proteus is a common cause of complicated UTIs.