Working with chemicals and bacteria can be hazardous. In part two, set up a controlled experiment to measure the effect of each type of antibiotic on each type of bacteria. In part one, perform a gram stain on bacteria cultures to determine which are gram-negative and which are gram-positive. Hypothesis: Based on your research, write a detailed hypothesis predicting the answer to the question.Įxperiment: An experiment to test your hypothesis will need two parts. Observe/Gather Data: Do some research to find information about antibiotics and gram staining, so that you can make an informed hypothesis. Question: Will four common antibiotics (Penicillin, Ampicillin, Neomycin, and Erythromycin) have the same effect on both gram-negative and gram-positive bacteria? Gram staining helps doctors make a diagnosis, but can it also help suggest a cure? What is the relationship between gram classification and antibiotic use? Do common antibiotics interact differently with gram-positive and gram-negative bacteria? Answer these questions through experimentation. For example, the bacteria that causes scarlet fever is gram-positive, while that which causes typhoid or cholera is gram-negative. Even the simple determination that a bacteria specimen is gram-positive or gram- negative can direct a doctor in diagnosis, as different bacteria cause different diseases. In the process, he discovered that bacteria could be divided into two different groups - one that retained a stain, called ‘gram-positive,’ and one that didn’t, called ‘gram-negative.’ His unique method for identifying these two groups became the first step in any bacterial identification process. In 1884 Hans Christian Gram, a Danish bacteriologist, attempted to find a universal stain that would work with all bacteria. Similarly, Hemophilus spp., Legionella app, and some anaerobic bacteria stain poorly with safranin.Ever heard about gram staining and antibiotics? Here’s how it started. Some laboratories use safranin as a counterstain however, basic fuchsin stains gram-negative organisms more intensely than safranin. The final step in gram staining is to use basic fuchsin stain to give decolorized gram-negative bacteria pink color for easier identification. The length of decolorization is a critical step in gram staining as prolonged exposure to a decolorizing agent can remove all the stains from both types of bacteria. In contrast, solvent dehydrates the gram-positive cell walls with the closure of pores preventing diffusion of violet-iodine complex, and thus, bacteria remain stained. With the dissolution of the lipid layer, gram negatives lose the primary stain. Initially, all bacteria take up crystal violet dye however, with the use of solvent, the lipid layer from gram-negative organisms is dissolved. Gram-positive microorganisms have higher peptidoglycan content, whereas gram-negative organisms have higher lipid content. The basic principle of gram staining involves the ability of the bacterial cell wall to retain the crystal violet dye during solvent treatment. Subsequently, a decolorizer, often solvent of ethanol and acetone, is used to remove the dye. The next step, also known as fixing the dye, involves using iodine to form crystal violet- iodine complex to prevent easy removal of dye. The first step in gram staining is the use of crystal violet dye for the slide's initial staining. The organisms that do not take up primary stain appear red under a microscope and are Gram-negative organisms. The term for organisms that retain the primary color and appear purple-brown under a microscope is Gram-positive organisms. Often the first test performed, gram staining involves the use of crystal violet or methylene blue as the primary color. It gets its name from the Danish bacteriologist Hans Christian Gram who first introduced it in 1882, mainly to identify organisms causing pneumonia. ![]() The Gram staining is one of the most crucial staining techniques in microbiology.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |