+ vs -

Hi everyone!!! As I mentioned, I am a Biology student.  How can a Biology student have a blog without any Biology posts?  So here is the first one.  This post is about the components of the cell wall of bacteria.  There is a staining procedure known as Gram stain, that uses a series of dyes and reagents (as iodine and water) to stain the cell wall of bacteria, allowing us to identify and classify them in two groups.  These are Gram + and Gram -, the first one stains purple, and the second one red .  The bacteria in each of these groups stain different because of the structure of their cell wall.  Gram + bacteria have an abundant amount of peptidoglycan; a polymer of sugars and amino acids that forms a layer outside the bacteria constituting their cell wall.  This polymer, also known as murein, confers the bacteria with resistance and protection because it acts as a strong virulence factor.  Gram + bacteria also have teichoic acids on their cell wall, that gives them extra protection against phagocytosis (the process in which white blood cells or phagocytes engulf an antigen, in this case bacteria, and subsequently eliminate it).  By the other hand, Gram - bacteria have less concentration of peptidoglycan on their cell wall.  They reward this deficiency with lipopolysaccharides on their cell wall which are toxic.  These lipopolysaccharides (LPS), also known as endotoxin A, are made of lipids (as the name suggests) which are not good inductors of the Immune System of our bodies.  Due to this characteristics they are specially dangerous when the cell wall undergoes lysis.

Why do we have to know something like this and pay extra attention?  Suppose that we have a human (women are at greater risk) with an urinary infection caused by cross-infection of Gram - bacteria (commonly E. coli in the rectal tract that can reach urinary bladder through the vagina).  If a lytic breakdown is taking place and all of the Gram - bacteria that where taking part of that infection break, all the endotoxin A or LPS is released into the bloodstream; causing what is known as an endotoxic shock.  This is known as an immune-physiologic chaos in the body.  It activates all body's coagulation system indefinitely, in a manner that it runs out.  Here the person can suffer an hemorrhage and regrettably die of a DIC (Disseminated Intravascular Coagulation).  This process occurs and we do not realize what is happening in our body.  So NOW YOU KNOW A VERY GOOD AND IMPORTANT REASON not to miss any undetected infection (or what seems to be an infection) on your body.  Is important that we visit a doctor to help fight, in the correct way, any microorganism that can invade us.  Even if I know that you are scared (as I first was) after knowing this: Smile :)

Here is a photo (which I got from Google) of the differences in the cell wall of the Gram + and Gram - bacteria.