Antibiotics Definition: What is their function & mechanism of action

Antibiotics are the some of the most valuable and indispensable drug molecules in the present world.

Many people survive from deadly infectious and communicable diseases like tetanus, septicemia, typhoid, tuberculosis,  etc. due to these antibiotics.

Use of antibiotics greatly decreases untimely mortality of many infected patient.

There are many types and are selected based on the prior experience or by antibiotic sensitivity test for the said infection.

There use has become inevitable and in most cases medicos prescribe them for even simple diseases like cough and cold.

Irrational use of antibiotics has be come an issue as there is development of resistance by bacteria.

Yet, this is avoided or over come by use multiple types of antibiotics. But World health organization is worried that so of the bacteria had developed resistance to most antibiotics which is alarming to the medical world.

Antibiotics Definition:

Antibiotics are natural or semi-synthetic molecules which in small concentrations destroy bacteria and other microbes in the body.

Their specialty is they kill the microbes without affecting the body into which they were administered. This is again due to specificity or selectivity for the bacteria and not the body of administration.

Types of antibiotics:

1. Sulfonamide groups
2.  β-Lactam antibiotics
3. Tetracyclins
4. Macrolide antibiotics
5. Quinolones and floroquinolnes
6. Anti-TB, Anti-leprosy

Function & mechanism of action of these antibiotics:

Antibiotics especially kill bacteria and hence this creates their selectivity. Bacterial cell has different physiology and  anatomy than human and animal cells.

1. Attacking and damage to cell wall : Antibiotics like penicillin, cephalexin damage the cell wall of bacteria. Human cells don’t have cell wall hence these are not affected. These antibiotcs cause pores in the cell wall which can lead to osmosis due to excess influx of water so that cell swells or loss of water so that cell shrinks and thus cell is burst & damaged.
2. Attack on ribosomes & inhibit their growth and multiplication: Tetracycline, streptomycin etc antibiotics specially attack bacterial ribosomes and inhibit protein formation. Thus bacteria don’t grow and multiply and are killed. Human cell ribosome is different from bacterial ribosome and hence they are not affected. (Bacteria ribosomes have 70’S ribosome while animals and plants have 80’S ribosomes).
3. Attack DNA synthesis; Antibiotics like ciprafloxacin, oflaxacin etc. attack DNA related enzymes of bacteria which are quite different from those of humans and hence kill them without harm to our body.