Bactrim DS consists of which two active ingredients?

• A. Amoxicillin and Clavulanate
• B. Trimethoprim and Sulfamethoxazole
• C. Ciprofloxacin and Levofloxacin
• D. Vancomycin and Gentamicin

Answer: (B)

Bactrim DS is a combination antibiotic that contains two active ingredients: trimethoprim and sulfamethoxazole. This combination works synergistically to inhibit bacterial folate synthesis, which is essential for the production of nucleic acids and ultimately bacterial growth and replication. Trimethoprim acts by inhibiting dihydrofolate reductase, while sulfamethoxazole inhibits dihydropteroate synthase, leading to a more effective antimicrobial action than either drug could achieve alone.

The other combinations listed do not contain these specific ingredients; for example, amoxicillin and clavulanate are a different class of antibiotics altogether and are often used for various types of bacterial infections. Ciprofloxacin and levofloxacin are fluoroquinolones, which target bacterial DNA gyrase and topoisomerase IV, and are distinct from the mechanism of action seen in Bactrim. Similarly, vancomycin and gentamicin belong to different antibiotic classes and target different aspects of bacterial metabolism and cell wall synthesis. Understanding the components of Bactrim DS is crucial for appropriate clinical application and for distinguishing it from other antibiotics used in practice.