Which staining technique is best matched with its appropriate example?

• A. Acid-fast stain — visualizing bacterial endospores
• B. Negative stain — detecting flagella
• C. Simple stain — distinguishing Mycobacterium tuberculosis from other bacteria
• D. Gram stain — differentiating between Gram-positive and Gram-negative bacteria

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the purpose of each staining technique mentioned. For example, the acid-fast stain is primarily used to identify bacteria with waxy cell walls, such as Mycobacterium species.
2. Step 2: Match each staining technique with its correct application based on microbiological principles. For instance, the Gram stain differentiates bacteria based on cell wall structure into Gram-positive and Gram-negative groups.
3. Step 3: Recognize that the acid-fast stain is not used for visualizing bacterial endospores; instead, the endospore stain (such as the Schaeffer-Fulton method) is used for that purpose.
4. Step 4: Know that the negative stain is typically used to visualize capsules or to observe cell morphology without heat-fixing, but it is not used for detecting flagella; flagella staining requires special mordants and techniques.
5. Step 5: Identify that the simple stain involves using a single dye to highlight cell shape and arrangement but does not distinguish Mycobacterium tuberculosis specifically; acid-fast staining is used for that.