Time dependent killing is shown by –
**Core Concept**
Time-dependent killing refers to the bactericidal activity of antibiotics that increases with the duration of exposure to the microorganism. This phenomenon is crucial in understanding the pharmacodynamics of antibiotics, particularly in the treatment of infections caused by susceptible organisms.
**Why the Correct Answer is Right**
The correct answer is a class of antibiotics known as beta-lactam antibiotics, such as penicillins and cephalosporins. These antibiotics inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs). The longer the exposure to beta-lactam antibiotics, the more PBPs are inhibited, leading to increased bacterial cell lysis and death. This time-dependent killing is a hallmark of beta-lactam antibiotics and is a key factor in their effectiveness against susceptible organisms.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because beta-lactamase inhibitors, such as clavulanic acid, do not exhibit time-dependent killing. Instead, they inhibit the bacterial enzyme beta-lactamase, which breaks down beta-lactam antibiotics.
**Option B:** This option is incorrect because aminoglycosides, such as gentamicin, exhibit concentration-dependent killing. Their bactericidal activity increases with the peak concentration achieved in the target tissue.
**Option C:** This option is incorrect because fluoroquinolones, such as ciprofloxacin, exhibit concentration-dependent killing. Their bactericidal activity increases with the peak concentration achieved in the target tissue.
**Clinical Pearl / High-Yield Fact**
When prescribing beta-lactam antibiotics, it's essential to consider the time-dependent killing phenomenon and ensure that the dosing regimen provides adequate exposure to the antibiotic to achieve optimal bactericidal activity.
**Correct Answer: C. Beta-lactam antibiotics, such as penicillins and cephalosporins, exhibit time-dependent killing by inhibiting bacterial cell wall synthesis through binding to penicillin-binding proteins (PBPs).**