How antimicrobial drug kill the microbes?

Question

How antimicrobial drug kill the microbes?

Answer 1

Penicillin interferes with bacterial cell wall synthesis.

Other antibiotics interfere with bacterial protein synthesis.

Answer 2

The previous poster has put it very succinctly and very well.  (Thumbs up, kozar!)  

I will just add that antimicrobials work in a large number of different ways, and by using that particular word you are actually (perhaps inadvertantly) including antivirals, antiparasitics and antifungals as well as antibiotics (which kill bacteria), so there are even more possibilities for the method of action.  There is also a bit of crossover between drugs that are used against various classes of microbes.

Not all antibiotics are specifically lethal to the bacteria (bacteriocidal).  Some just stop them from being able to reproduce (bacteriostatic).  Other classes that act on other microbes may also have this differentiation.