1. Agar media can be enriched with blood for the identification of: - Viruses from other microorganisms - Bacteria which can grow in anaerobic conditions - Bacteria which can grow in higher hydrostatic pressure - Bacteria which can cause hemolysis 2. Isolation of pure culture refers to: - Growing microorganisms on a surface - Separation of a single colony - Introduction of inoculum - Purification of culture 3. A rapid qualitative isolation method involving spreading a loopful of inoculum over the surface of an agar plate is known as: - Stabbing - Identification - Streaking - Isolation 4. A subculture is a: - Culture made from a contaminant - Culture made in an embryo - Culture made from an isolated colony - Colony growing beneath the media surface 5. Which of the following methods can be used to determine the number of bacteria quantitatively? - Streak-plate - Pour plate - Pour-plate and spread plate - Spread-plate 6. Addition of blood to culture medium only allows the hemolytic bacteria that grow on a plate to be picked out. This is an example of: - Selective media - Differential media - Chemically defined media - Complex media 7. Elective media facilitate the growth of only one kind of organism. Sabouraud medium is used to selectively isolate: - Acid-fast organisms - Gram-positive bacteria - Coliform bacteria - Yeasts 8. In the pour-plate method, the medium should be maintained at what temperature? - 45 degrees C - 0 degrees C - 37 degrees C - 67 degrees C 9. The term that refers to the purposeful addition of microorganisms into a laboratory nutrient medium known as: - Contamination - Disinfection - Inoculation - Isolation 10. Which of the following refers to specific procedures used to prevent unwanted microorganisms from contaminating the clinical specimen? - Inoculation - Disinfection technique - Aseptic technique - Needle technique 11. Bacteria that require special growth factors and complex organic substances are called: - Pathogenic - Aerobic - Chemoheterotroph - Anaerobic - Fastidious 12. A microbiology student notices that a culture broth tube was very turbid at the bottom of the tube but clear at the top of the tube. It can be concluded that the: - Organism should be grown in an anaerobic chamber - Organisms are aerobes - Organism can tolerate oxygen - Broth is sterile - Organism cannot produce superoxide dismutase and/or catalase 13. A characteristic of agar is: - It solidifies at 42 degrees C - A common source of nitrogen in liquid media - A polymer extracted from algae that has no nutritional value - It is solid at room temperature 14. Advantage of an agar slant preparation is: - Microbes can slide on agar easily - Less agar powder is needed - More surface area for growth of microbes 15. Which of the following instruments or equipment is used for sterilizing the media after it has been prepared? - Laminar air flow chamber - Inoculating needle - Incubator - Autoclave 16. A culture medium consisting of agar, human/sheep blood, and beef heart is a: - Complex media - Selective media - Reducing media - Chemically defined media - Differential media 17. What is the application of selective medium? - It allows growth of all the microbes inoculated to it - It allows the growth of one species of microorganisms while suppressing the growth of others - It does not allow the growth of any kind of microbes
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Agar media can be enriched with blood for the identification of: Bacteria which can cause hemolysis. Blood agar is a type of differential media that allows for the identification of bacteria based on their ability to break down red blood cells and cause hemolysis. Show more…
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Introduction: Selective and differential media are used frequently in Microbiology Pathology Labs to identify a known group of bacteria from a complex mix of other bacteria. The medium is designed to select against as many of the background organisms as possible by using a medium in which they will not grow but the organisms under investigation can grow hence the ‐Selective‐ part of the name. Any assayable characteristic that can be used to differentiate a specific group of interest from the selected group of organisms can be incorporated into the medium to distinguish that group. The aim of this Lab is to understand use of selective/differential media and the interpretation of their results. Mannitol salt agar Contains: 7.5% NaCl included with the sugar mannitol, a source of protein, pH indicator (phenol red) Selection: The high salt concentration selects against salt intolerant organisms and for halophiles (salt tolerant organisms). Describe your results Eosin methylene agar Contains: EMB contains: peptone, lactose, dipotassium phosphate, eosin Y (dye), methylene blue (dye). Selection: Eosin and methylene blue together inhibit the growth of gram positive bacteria and encourage the growth of gram negative bacteria including coliforms Differentiation: Lactose is a fermentable carbohydrate that differentiates between organisms that ferment lactose (e.g., E. coli) and those that do not. In our plate Escherichia coli went through fermentation because it produced a metallic green sheen. The other samples produced pink colonies, which means they were slow or weak fermenters MacConkey agar: Contains: Protein source, lactose, bile salts, and the dyes crystal violet and neutral red. Selection: Bile salts and crystal violet make the medium selective by inhibiting the growth of gram-positive bacteria but allowing many gram negatives (including coliforms) to grow. Differentiation: Lactose is a fermentable carbohydrate that differentiates between organisms that ferment lactose (e.g., E. coli) and those like Pseudomonas and Klebsiellosis that do not. In our plates we did not yield any results because the plates were covered with a thin layer of MacConkey agar. Describe your results Triple sugar iron agar Contains: Carbon sources Three sugars, glucose (0.1%), sucrose (1%), and lactose (1%) and peptone as a source of protein.
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You have inoculated a SIM tube and 24 hours later have recorded the following results. The medium is partially black, turbid throughout, and there is no red ring when you add Kovak's reagent. Indicate which of the following represent the correct interpretation of these results. (Check all that apply) Check All That Apply indole + indole - mannitol fermentation + mannitol fermentation - motile nonmotile H2S + H2S - methyl red - methyl red +
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