Time dependent killing is shown by
**Core Concept**
Time-dependent killing refers to the bactericidal action of antibiotics that is directly proportional to the duration of exposure to the microorganism. This concept is crucial in understanding the pharmacodynamics of antibiotics and their optimal dosing regimens.
**Why the Correct Answer is Right**
Time-dependent killing is characteristic of beta-lactam antibiotics, such as penicillins and cephalosporins. These antibiotics inhibit cell wall synthesis in bacteria, ultimately leading to cell lysis and death. The bactericidal activity of beta-lactams is directly related to the time the antibiotic remains in contact with the bacterial cell, making time-dependent killing a key aspect of their pharmacodynamics.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because beta-lactamase inhibitors, such as clavulanic acid, are not primarily known for their time-dependent killing activity.
* **Option B:** This option is incorrect because aminoglycosides exhibit concentration-dependent killing, where the bactericidal activity is directly proportional to the peak concentration of the antibiotic.
* **Option C:** This option is incorrect because fluoroquinolones, such as ciprofloxacin, exhibit concentration-dependent killing, where the bactericidal activity is directly proportional to the peak concentration of the antibiotic.
**Clinical Pearl / High-Yield Fact**
To remember the key difference between time-dependent and concentration-dependent killing, consider the following: time-dependent killing is like a "timer" that counts down to cell death, whereas concentration-dependent killing is like a "bomb" that explodes when the concentration reaches a certain threshold.
**Correct Answer: B. Aminoglycosides exhibit concentration-dependent killing.**