Lab Safety and Bacterial Identification Techniques, Exams of Nursing

Download Lab Safety and Bacterial Identification Techniques and more Exams Nursing in PDF only on Docsity! 1 Answer the following questions 1. What three elements are used in an autoclave to sterilize equipment? heat, pressure, and steam 2. What is the minimum temperature an autoclave must be set at to achieve sterile condition? 125°C 3. If you are working in a lab in which an autoclave is not available, and you are pressed for time, which would you chose to best sterilize your equipment? Hot steam or hot air? Explain why you chose your answer. Hot steam is the best choice as you can achieve a sterile environment in a matter of minutes whereas hot air will take several hours to achieve the same effect. 4. What type of incubator is pictured below? Fixed incubator 2 Answer Key 5 3. Identify the part of the microscope indicated by the arrow. Course focus 1. You are about to study a bacterial sample under a light microscope. You look into the oculars and see two circles. What adjustments need to be made? Compress or expand the oculars until a single circle can be seen while using both eyes simultaneously. 2. What 2 parts of the microscope contributes to the total magnification to your sample? 6 Objective and oculars (eyepiece) 7 3. As you looking through the microscope you wish to dim (or limit) the amount of light entering into the eyepiece—what component of the microscope other than the light source itself can be adjusted to make these modifications? Diaphragm 1. What objective power is best suited if you are uncertain what the sample is and where to begin? 4x (or lowest power objective) 2. You are viewing a sample of bacteria that is 3 mm in diameter through a 40x objective lens. The eyepiece has a magnification power of 10x. What size will the sample appear through the eyepiece? 1200 mm in diameter (or 400x’s larger) 3. Based on the microscope shown in the lab lecture, which objectives would NOT require placing oil on the slide? 4x, 10x and 40x LAB 3 1. List the 4 main steps used to prepare a DRY mount and indicate which step is optional. 1 – Clean slide 2 – Circle area on slide for specimen placement (OPTIONAL) 3 – Apply organism to slide 4 – Air dry at room temperature 2. Why is it important to first clean your slide before applying your sample? 10 Nigrosin is a negatively charged dye. The membranes of most cells are also negatively charged. The membrane will repel the dye not allowing it to be absorbed. 1. What is one disadvantage of heat fixing a sample? 11 The heat fixing procedure kills the specimen. This also prevents any observations on motility and enzymatic properties. 2. What is the proper way to dispose of all materials used during the lab? All materials must be place in a biohazardous waste bag and placed into an autoclave for sterilization. 3. What are the Gram status, shape and identification of organism #2 from the Gram stain procedure? Gram-negative; Bacillus (rod); E. Coli 4. What are the Gram status, shape and identification of organism #5 from the Gram stain procedure? Gram-positive; Cocci (spherical) chain; Streptococcus LAB 4 1. What type of media is best used to eliminate certain bacteria from within a mixed culture? Selective media 2. According the lab module, what type of agar plate is the most commonly used nutrient agar? What color is it? LB agar; Light (or pale) yellow 12 3. What was the name of the selective agar plate (shown below) that is similar to a blood agar plate? MacConkey agar 15 Individual colonies were observed within Phase 3. 2. Identify the plating method (below) as demonstrated in the lab. Quadrant growth 3. Identify the organism growing on the TOP half of the agar and describe the observed hemolytic properties. Staph Aureus; Beta hemolysis is observed based on the zones of clearing within the red agar. 16 4. Would you expect to see a color change when pseudomonas is streaked onto an EMB agar plate? Explain your answer. No. There would not be a color change because pseudomonas does not ferment lactose. 17 Lab 5 1. The Kirby-Bauer method for examining antibiotic sensitivity is also known as what? The Standardized Disc Susceptibility Test 2. True or False. The antibiotic discs are placed onto the LB agar plate before spreading the bacterial culture on the plate. False. The antibiotic discs are place onto the plate AFTER the culture has been spread. 3. When performing the Kirby-Bauer method the areas of clearing surrounding an antibiotic disc after an overnight incubation are known as what? Zones of Inhibition. 1. Why was an LB agar plate used to test the Staph culture as opposed to a selective/differential agar that only grows Staph? LB agar is used as it simply provides the nutritional requirements to encourage bacterial growth. Since the results of the Kirby Bauer method is directly based on bacterial growth patterns, no other selective or differential additives should be present that may hinder or inhibit the samples growth. 2. What unit of measurement is used when determining the size of the zones of inhibition? A. Centimeters B. Micrometer C. Millimeters D. Meters 20 LAB 6 1. True or False. The presence of cytochrome C is often associated with aerobic bacteria. 21 True 2. Which STD is most often identified using the Oxidase test? Gonorrhea 3. Using the catalase test, a Staphylococcus sample would be: A. Gram (+), Catalase (+) B. Gram (-) Catalase (+) C. Gram (-), Catalase (-) D. Gram (+), Catalase (-) A. Gram-positive, Catalase-positive. 4. True or False. The catalase test is a qualitative and selective assay. False. The catalase test is a qualitative and differential assay. 1. Fibrin is another term for ? blood clots 2. Once you inoculate the rabbit plasma containing media for the coagulase test, how long do you wait to read the sample results? A. 1-2 hours B. 3-6 hours C. 8-10 hours D. 12-14 hours D. 12-14 hours which is the equivalent of an overnight incubation. 3. What specific bacterium was mentioned to be coagulase positive and resistant to antibiotics? Staph aureus. 4. The hydrolysis of triglycerides on a spirit blue agar plate most closely resembles that of 22 hemolysis on a blood agar plate. A. Gamma 25 3. Enteric bacteria are often found where? Give an example of one. Enteric bacteria around found in either the intestines or gut. Examples given in the video were either Salmonella or Shigella. 1. According to the lab module, which 5 wells of the API strip should be layered with mineral oil? 26 ADH, LDC, ODC, H2S and URE 2. How many milliliters of water were added to the tray prior to incubating the strip at 37C overnight? 5 mL 3. What is the main advantage of using the API test? The API test allows for rapid characterization by simultaneously assessing 20 different enzymatic properties of a given microbe. 4. Enter the API Code for S1 and S2 from the lab here: S1: 5044550 S2: 2206002 API ANSWER KEY LAB 8 1. The word ‘antigen’ is actually a combination for what two words? Antibody-generating 2. For the ELISA assay depicted below, what do the arrows indicate? 27 The arrows indicate the wash steps. 3. What would happen in terms of the colorimetric readout if you forgot to do the wash step after Step D (above)? 30 2. In the wet lab portion of the video, what pathogen was the agglutination assay specifically designed to test for? Choose all that apply. A. E coli B. Salmonella C. Staph D. Strep C. Staph 3. What was the purpose of the first quadrant of the agglutination assay containing only the reagent? The first quadrant served as the reagent only negative control—you want to ensure the reagent by itself does not clump but rather requires the presence of Staph. 4. Based on the image below, which row (A or B) is negative for agglutination? Row A is negative for agglutination. 5. A patient with type O blood is sent to the lab for a blood-clotting assessment. Since type O blood contains no antigens, which quadrant (#1-6) best depicts the result you would expect to see once the assay is complete? 31 Quadrant 6 shows no signs of agglutination, which is only possible in the presence of antigens. Since Type O blood has no antigens, no clumping will occur during the test. Note: Quadrant 2 was stated to have clumping (albeit minimal) during the wet lab and is thus not an acceptable answer. 32 LAB 9 Using the observations made and recorded from PL09 Unknown Pathogen, complete the results sections accordingly. 1. Given Culture A and Culture B were accidentally mixed, what observations were made from the Gram stain (shown below)? Gram-positive cocci (spherical) clusters and Gram-negative bacillus (rods) were observed. 2. Given the results from a MacConkey agar plate shown below, what is the shape of Culture A? Culture B? Culture A BAP Plates Culture B  36 Using the observations made and recorded from PL09 Unknown Pathogen, complete the results sections accordingly. 1. Culture A and Culture B were streaked onto EMB plates. What does this tell you about each of the cultures? Describe your observations. EMB agar is both selective and differential media. EMB restricts Gram-positive and as such this again confirms Culture A is Gram-positive. Culture B clearly grew on the EMB plate, further confirming it is Gram-negative. A green metallic sheen was also observed which immediately suggests Culture B is E. coli. 2. Culture A and Culture B were assessed via the catalase test as shown below. State your observations for each culture. Culture A and B were both catalase positive meaning both are able to breakdown hydrogen peroxide (damages cellular integrity) into harmless hydrogen and water molecules. 37