Team:IIT Madras/Background
What are antibiotics?
Antibiotics, also known as antimicrobial agents are drugs that fight infections caused by bacteria. The key word in the previous sentence is bacteria. Antibiotics will have no effect if taken during a a viral infection like common cold, most sore throats and the flu. However, bacterial infections are a threat too, and antibiotics have served us well in fighting them for over 70 years. So how do they work? Antibiotics are chemicals that interact adversely with different components of a bacterium's structure and/or metabolism, thus bringing about their demise. For example some antibiotics like penicillins attack the cell wall and rupture it, others like tetracyclines target protein synthesis. The diagram below shows some of the molecular targets of antibiotics on bacterial cells.
How does resistance develop?
The emergence of antimicrobial resistance is an evolutionary mechanism. The bacterial population consists of several variants for each of it's gene. Essential proteins are being targeted by most of the antibiotics, which is mostly docking of drug to the protein. Among the variants, few proteins could have a property like they can function but the drug can not dock to the protein anymore. Now, the bacterial cells which have these proteins become resistant.
Antimicrobial peptides
Antimicrobial peptides (AMPs) function differently from the antibiotic molecules as they do not inhibit any protein of the pathogenic bacteria. There are various type of AMPs. In most of the cases, AMP molecules bind to the cell-wall of the bacteria and pierce through the cell wall and break it.
Resistance against anitmicrobial peptide
It has recently been shown that in vitro exposure of bacteria to slowly increasing cationic AMP concentrations over several hundred generations can result in reversible physiological adaptation and/or spontaneous, inheritable resistance to the peptide used.