Antibiotics and antibiotic resistance

Published on October 29, 2009   35 min

A selection of talks on Cell Biology

Hi, I'm Gerry Wright from McMaster University in Hamilton, Ontario. In this lecture, I will discuss antibiotics and antibiotic resistance and provide you with an overview of these two areas.
The talk will be divided into two sections. In the first, we'll discuss what antibiotics are and how they work, and in the second one, we'll cover various modes of antibiotic resistance and discuss in some detail, some specific classes of resistance and their genes.
So first section one, antibiotics. What are they and how do they work?
First, what are antibiotics? Well, antibiotics are small molecules. By small molecules, we mean molecules that have a molecular mass of less than 3,000 Daltons to distinguish them from larger macromolecules like proteins. They block the growth of microorganisms, including bacteria and fungi. This growth inhibition can result in the death of the cell. In these cases, we call them bactericidal or in the case of fungi, fungicidal compounds, or they can simply stop the cells from growing. These will be called static molecules, bacteriostatic or fungistatic.
First, let's start with some definition. Antibiotics rigorously are natural products that inhibit the growth of bacteria. These are molecules like penicillin and erythromycin. By natural products, we mean molecules that are produced by living systems. Genetically encoded small molecule. Antibacterial agents would include compounds that are not natural products of it, that is synthesized by chemists that also have those similar kinds of properties. Ciprofloxacin is a good example of it. However, over the years, the term antibiotics has served to cover both of these areas. Although in the literature you may see antibacterial agents being distinguished from antibiotics from this one. Anti-infective agents include antibiotics and antibacterial agents, and any compound that will inhibit the growth of a microorganism. So this includes antifungals, anti-parasitic agents, and even antiviral. Another term that is often used in the field, is spectrum. A broad-spectrum antibiotic impacts many microbial species. Whereas a narrow-spectrum antibiotic, has some selectivity towards just a few species are general. In order to discuss antibiotic activity and antibiotic resistance,