In MIC susceptibility testing, a lower concentration indicates more sensitivity to the antibiotic. Which choice reflects that statement?

• A. A lower MIC indicates more sensitivity
• B. A higher MIC indicates more sensitivity
• C. The MIC does not relate to sensitivity
• D. MIC only indicates bactericidal effect

Answer: (A)

Understanding how MIC reflects antibiotic sensitivity in susceptibility testing. The minimum inhibitory concentration (MIC) is the lowest concentration of an antibiotic that prevents visible growth of a microorganism after incubation. A low MIC means the organism is inhibited by a small amount of drug, so it is more susceptible to that antibiotic. If the MIC is high, you need much more drug to inhibit growth, indicating lower sensitivity or resistance. The MIC measures inhibition, not necessarily killing—the related concept of bactericidal activity is described by the minimum bactericidal concentration (MBC). Therefore, a lower MIC best represents greater sensitivity to the antibiotic.