Antibiotics are chemical compounds that are used to inhibit the growth of or completely destroy micro-organisms. Ironically, these compounds were first derived from certain microorganisms. Before we get into what and How, we need to know why we are talking about these agents.

• There are organisms that are not visible to the naked eye of humans all around us and inside us.
• Some of these organisms are good and some are not.
• The organisms that make us sick and ill are those not good micro organisms.
• Over time in history there have been a lot of life threatening illness that were caused by these organisms.
• To prevent the sickness or treat them, we are using certain agents that are capable of doing that.

There are many kinds of micro-organisms:

• Bacteria
• Archaea
• Microscopic Animals
• Protozoa
• Fungi
• Mold
• Algae

Bacteria are sometimes also called as eubacteria or true bacteria. We will be looking at them the most because they are the most likely causative agents that cause infections.

Oh.. Right “Infection”. So, an Infection is an illness or sickness caused by any of the micro organism. Depending on the type of the organism, we classify infections.

When we talk about bacteria, we mainly talk about the two types of bacteria.

1. Gram Positive
2. Gram Negative

So, Before we start to dive deep into antibiotics we need to know the difference between gram negative and gram-positive bacteria.