Which of the following statements best describes the necessity of performing antimicrobial susceptibility tests for infectious agents?

• A. Antimicrobial susceptibility testing is only necessary for infectious agents known to have variable resistance patterns.
• B. Antimicrobial susceptibility testing is never required because all microbes respond similarly to antibiotics.
• C. Antimicrobial susceptibility testing is essential for all infectious agents to determine appropriate treatment.
• D. Antimicrobial susceptibility testing is only performed for viral infections.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the purpose of antimicrobial susceptibility testing (AST). AST is performed to determine which antibiotics an infectious agent is sensitive or resistant to, guiding effective treatment choices.
2. Step 2: Recognize that not all microbes respond the same way to antibiotics; some have variable resistance patterns, making AST important to identify the best therapeutic option.
3. Step 3: Evaluate the options: AST is not needed for all infectious agents universally, nor is it irrelevant; it is also not performed for viral infections since antibiotics target bacteria, not viruses.
4. Step 4: Conclude that AST is particularly necessary for infectious agents known to have variable resistance patterns, ensuring that treatment is tailored and effective.
5. Step 5: Summarize that the best description is that antimicrobial susceptibility testing is only necessary for infectious agents known to have variable resistance patterns.