Antibiotics are medications produced by bacteria and fungi. It is used to treat bacterial infections by killing or reduce the growth of bacteria.
Mechanism:
1. They attack the wall or coating that surrounds bacteria.
Some of them insert themselves into the cell membrane to depolarise it, such as daptomycin; Some damage the structure of the outer membrane, for example, colistin. ß-lactam antibiotics, where penicillin belongs to, kill bacteria by binding to bacterial enzymes called PBPs (penicillin binding proteins). These proteins link to part of the cell wall and are responsible for building and repairing it.
2. They interfere with bacteria reproduction.
They stop DNA replication of the bacteria by several methods. Some block the enzyme activity for the synthesis of folic acid, which is essential for the synthesis of the DNA bases. Some bind to the enzymes that are involved in forming double helix shape of DNA.
3. They block protein production in bacteria.
They block RNA polymerase or bind with ribosomes or the enzymes work with ribosomes in the bacteria to stop protein synthesis.
The first antibiotic:
The first antibiotic was discovered accidentally by Alexander Fleming. He noticed something unusual on one dish when he was sorting through the dishes in the lab. The fungus Penicillium notatum, had created bacteria-free zones wherever it grew on the plate. Fleming isolated and grew the mould in culture. He found it very effective in terms of decreasing the growth of bacteria even at very low concentrations. At the same time, it was less toxic than other disinfectants.
Antibiotic resistance:
Antibiotic resistance is one of the biggest threats to global health, food security and development nowadays, according to WHO.
How does it happen?
As we use the antibiotics, some germs (bacteria and fungi) survive. They are then resistant to the antibiotics used. Surviving germs multiply and produce more antibiotic-resistant germs. In this situation, antibiotics become less effective. Moreover, misuse of antibiotics also lead to antibiotic resistance. Sometimes the germs are not completely killed due to the incorrect dosage of the antibiotics, and thus they become more resistant.
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