In this episode of #KnowingYourJargon we discuss bugs. Not just any bugs, but bacteria. Thousands of types of bacteria are found in and around us. Some are friends that offer some protective or digestive function and often called "Normal Flora", others cause infection and disease, these are collectively called pathogens.
Two of the largest groups of bacteria are called Cocci, and Bacilli. They differ by their shape. Cocci are spherical, whereas bacilli are rod shaped. Bacteria are classified as neither an animal nor a plant, they exist in their own group that hovers between both. As such their cell structures are more similar to plants because they have tough cell walls made of complex sugars (carbohydrates) whereas animals have cell membranes made of lipids (fat- cholesterol actually).
Now I know you have heard of Gram negative and Gram positive organisms, but what does it mean?
In the mid 1880s a Danish bloke, Hans Christian Gram developed a method of putting a Crystal Violet Dye on bacteria cultures to stain them for microscopy. While performing autopsies in a German morgue, he discovered that some bacteria would absorb the dye and therefore would be easily visible under microscope.
Gram calked these his Gram positive bacteria. Those bacteria that didn't take up the dye were therefore calked Gram Negative. A common great example of a gram negative bacteria is E-coli found abundantly as normal flora in your gut. And the pathogenic Typhoid bacillus where Gram first discovered that some bacteria wouldn't pick up his violet stain.
Rock Stars in the gram positive world include staphylococcus, streptococcus and some types of mycobacterium.
So, perhaps not the most interesting if information, but I bet you've wondered why some are called gram positive and some are called gram negative.
Now the application of this information became more important later in medicine. Gram just used his stain to see the bugs more clearly in the tissues he was studying.
Fast forward 45 years and we find ourselves in the final years of 1920s, the party and glitz of the Gatsby years is drawing to a close and the great New York stock market crash is imminently about to plunge the western world into depression. A brilliant young Scotsman called Alexander Fleming, a (biologist) discovered that in a bacterial (staphylococcus) culture on an agar plate, there was a spot of green mould that seemed to exude a substance that killed the bacteria around it on the culture. Penicillin had been discovered. 12 years he failed to get this discovery recognised as a medicine, then at the beginning of WW2 that Florey and a mob of doctors developed into a pharmaceutical grade product to treat infections. The dawn of the Antibiotics had begun.
So ... Great Rob! Now connect the dots for me...
Penicillin (and other Beta-lactam) antibiotics are large molecules. Penicillin was found to be very effective on Gram positive bugs, but not so good on gram negatives.
It was later discovered that the "tough to kill" gram negative pathogens, possessed a ring of lipid (fat) around their sugary cell walls. Like a condom acting as a barrier preventing the large penicillins in. It was at the same time discovered that this same barrier prevented Gram's violet stain from sticking to the sugar wall. Where gram positive bacteria had no lipid barrier, the crystal violet stain can stick to the sugary cell wall... Thus these visible bugs are called Gram positive, and we know that both the stain and the penicillin can get in and destroy the inner workings of the pathogen.
...
Blank face??
Well I find it interesting!!
More... Pre register for our newest seminar on drugs and how they work. "Rusty Pills" is coming to a location near you. Expressions of interest to admin@ect4health.com.au
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