A patient is taking tetracycline, a broad-spectrum antibiotic, to help manage acne. The patient has been on the medication for five months. Which of the following may be lower in this patient while on this medication?

• A. Production of antigens.
• B. Formation of platelets.
• C. Metabolism of sugars.
• D. Production of vitamin K.

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the role of tetracycline as a broad-spectrum antibiotic that affects not only pathogenic bacteria but also the normal flora of the body, especially in the gut.
2. Step 2: Recognize that the normal gut flora includes bacteria that synthesize vitamin K, which is essential for blood clotting and other physiological functions.
3. Step 3: Consider that prolonged use of tetracycline can reduce the population of these vitamin K-producing bacteria, leading to decreased production of vitamin K in the body.
4. Step 4: Analyze why other options such as production of antigens, formation of platelets, or metabolism of sugars are less likely to be directly affected by tetracycline use compared to vitamin K production.
5. Step 5: Conclude that the most likely effect of long-term tetracycline use in this patient is a reduction in vitamin K production due to disruption of gut microbiota.