microbiology lab practical final

microbiology lab practical final - Caroline Cox Micro-lab...

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Caroline Cox 4/24/08 Micro-lab Microbiology Lab Final Practical 1. Dilution lab a. Know how to calculate the final dilution on a plate or in a test tube b. Know how to calculate the dilution problems WITHOUT A CALCULATOR. c. Look over sample problems 2. Standard Qualitative analysis of water: a. Know the 3 different parts of this test i. Part A presumptive test 1. Purpose is to determine the presence of coliforms in a water sample and obtain an index as to the probable number of organisms present ii. Part B confirmed test 1. To verify the presence of coliform bacteria in a water sample for which the presumptive test was positive iii. Part C completed test 1. Confirm the presence of coliform bacteria in a water sample b. Name each part and list the media used in each part i. Part A: lactose fermentation broths containing Durham tubes ii. Part B: an EMB plate iii. Part C: single-strength lactose broth tube and a TSA slant c. Know +/- results for each part i. Part A: (+) if it turns yellow (acid production) and gas produced. Indicating a presence of coliforms ii. Part B: (+) a green sheen on the EMB plate and the water is nonpotable iii. Part C: (+) acid and gas in the lactose broth and the TSA slant growth contains gram-negative bacilli; and water source is contaminated with fecal material d. Be able to determine the most probable number from a chart e. Look over sample problems 3. Microbial analysis of food products: a. Know various examples of foods that have been deliberately processed with microbes i. Blue cheese 1. Penicillium ii. Soy sauce and tempura 1. Aspergillus iii. Cheese, yogurt, sauerkraut 1. Lactobacillus and Streptococcus b. Know the difference between i. food poisoning 1. an infection a bacterial species has been allowed to grow on the food for a period of time and after ingestion a person becomes sick with nausea, vomiting, or diarrhea after bacteria multiply in the gut ii. toxicity 1. intoxication results when organisms capable of producing an exotoxin are present on the food 2. As the organisms grow, toxins are released into the food. Signs and symptoms begins within a few hours after ingestion of the toxin iii. Spoilage
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1. Organisms generally produce an economic loss rather than a health threat c. Know various sources of fecal contamination of food i. Fertilization in some fields because runoff from pastures are contaminated with feces can contaminate adjacent crops ii. Food handlers do not wash their hands iii. A meat worker accidentally nicks the bowel and rinses the carcass with a hose, the meat will be contaminated with gut flora d. Sample problems 4. Antibiotic sensitivity testing: a. For each of the 7 antibiotics know: mechanism of action, side effects on the host, and scope of antimicrobial activity i. Sulfisoxazole 1. mechanism of action a. antimetabolite that competes with the essential metabolite PABA during the synthesis of folic acid in the microbial cell 2. side effects on the host a. sensitivity, blood dyscrasias (aplastic anemia), urinary tract disturbances
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microbiology lab practical final - Caroline Cox Micro-lab...

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