UPSC Express

Background: Working of Antibiotics

What are Antibiotics?

• Antibiotics are drugs that fight infections caused by bacteria.
• In order to be effective, it has to be selectively toxic to only target bacteria which are harmful.
• Antibiotics work in the following 2 ways
• Killing the bacteria
• Inhibiting the ability of bacteria to grow and multiply
• In order to understand the different targets a brief on bacterial cell is given below.

Bacterial cell

• A bacteria is a prokaryotic organism (no well-defined nucleus)
• The bacterial cell consists of :
  • A plasma membrane which encloses the cell components.
  • The cytoplasm is the jelly-like fluid that fills the inside of the cell.
• The DNA of bacteria is present in bacterial chromosome in the cytoplasm (see figure)
• Ribosomes are little granular bodies where proteins are made taking cue from the the DNA.
• Further, they reproduce through a process of binary fission through which the genetic information is carried forward.

Mechanism of Antibiotics

• Antibiotics work through many mechanisms that disrupt the structure and/or function of the bacteria.
• The structure or the function which the antibiotics target are called drug-delivery target.
• There are a number of drug-delivery targets in the bacterial cell namely
• Cell Wall
• Ribosome where protein synthesis occur
• Inhibit the DNA synthesis in order to stop it from transferring the resistant gene to other bacteria
• Inhibition of metabolism by introducing other non-harmful microbes to compete for nutrition

Antibiotic resistance: The hurdle 

• The problem with antibiotics is that the bacteria have developed resistance to certain antibiotics, and thus can no longer be used to control or kill the bacteria.
• Different mechanisms bacteria have adopted to resist antibiotics include
• Some bacteria pump an antibiotic out of their cells as fast as it enters.
• Some have proteins that bind to the antibiotic molecule and block its lethal effect.
• Some have enzymes that break down the antibiotic molecules.
• Penicillin hits the machinery that creates the cell wall.

In focus: Discovery of enzyme

• The new enzyme discovered helps in breaking cell walls of bacteria and hence, offers a potential for a new drug delivery target.
• This enzyme has been found to regulate the growth of the cell wall.
• Since the cell wall is fundamental for bacterial growth and division, it can be targeted in order to arrest the growth and multiplication of bacteria.
• As a result, it paves the way for new wave antibiotics.