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Introduction to Lab Ex. 14: Antibiotic Sensitivity Disc Diffusion Method

Introduction to Lab Ex. 14: Antibiotic Sensitivity Disc Diffusion Method. Introduction to Lab 10: Ex. Antibiotic Sensitivity Antibiotics are chemicals that are produced by other bacteria/fungi that have the ability to prevent other organisms (bacteria) from growing or killing them.

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Introduction to Lab Ex. 14: Antibiotic Sensitivity Disc Diffusion Method

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  1. Introduction to Lab Ex. 14: Antibiotic Sensitivity Disc Diffusion Method

  2. Introduction to Lab 10: Ex. Antibiotic Sensitivity Antibiotics are chemicals that are produced by other bacteria/fungi that have the ability to prevent other organisms (bacteria) from growing or killing them. These have been used widely in controlling bacterial infections in humans that cause diseases in humans. There have been many antibiotics that have been developed. These have been found to be effective in controlling various infectious bacteria in humans and thus used extensively in disease control (treatment of bacterial infections)

  3. While there are many different kinds of antibiotics and still many more kinds of bacteria, not all antibiotics are effective in inhibiting all bacteria. Hence, it is essential to determine whether an organism is sensitive to the inhibitory action of the antibiotic or not. Many procedures have been developed to determine antibiotic sensitivity. The most common method is the Disc diffusion method: Filter paper discs are saturated with specific amounts of certain antibiotics and placed on a growth of the particular bacterial culture to be tested. If growth is inhibited then sensitivity is seen If growth is seen then the culture is resistant to the antibiotic action and is not inhibited (which will mean that it cannot be used to treat an infection by the bacterium)

  4. It has also been discovered that antibiotics inhibit bacteria by stopping their growth (bacteriostatic) or by killing them (bactericidal). Antibiotics have been found to have different modes of action to inhibit bacteria:destruction of cell wall destruction of cell membrane inhibition of protein synthesis inhibition of DNA synthesis inhibition of intermediary metabolism Also, most antibiotics are effective only against bacteria (which have a prokaryotic cell structure and processes different from eukaryotic cells – resulting in antibiotics being effective primarily against prokaryotic cells i.e. other bacteria)

  5. The disc diffusion method - E.coli representing the Gram negative organisms - S.aureus representing the Gram positive bacteria Antibiotics that are effective against a wide range of bacteria (G+ and G-) are called broad spectrum Those that have effect against a small specific group of bacteria (either G+ or G-) are called narrow spectrum.

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