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49 Cards in this Set

  • Front
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gram positive examples. 2
bacillus megaterium
Bacillus Cereus
gram negative examples
E. coli
Pseudomonas aeruginosa
Acid fast examples
Mycobacterium smegmatis
Mycobacterium tuberculosis
spore former
bacillus megaterium
Bacillus Cereus
5 modes of action of antibiotics
1. Cell Wall
2. Metabolism
3. Cell membrane
4. Nucleic Acid
5. Protein Synthesys
Cell wall Antibiotic
Penicillin.
Bacitracin,
ampicillin
Cephalothin
Metabolism Antibiotic
tetracycline
triple sulfa
Chloramphenicol
clindamycin
kanamycin
Cell membrane antibiotic
Polymyxin B
Nucleic acid antibiotic
Rifampin
Novobiocin
Nalidixic acid
ciprofoxacin
Protein Synthesys Antibiotic
Exp streptomycin
Tetracyclines
Streak isolation procedure
1. sterilize loop
2. transfer loop to quadrant A
3. resterilze loop
4. pull bacteria from A to B
5. Resterilize loop
6. pull from B to C
7. Pull From C to D
Nosocomial
hospital acquired infections
1. Explain the difference between the cell wall of a gram positive and gram negative bacteria.
a. Gram positive thick peptidoglycan layer teichoic acid. They will retain the primary stain, crystal violet.
b. Gram negative thin peptidoglycan layer, no teichoic acid and an outer lipoploysaccharide membrane. Will not retain the primary dye and must be conouterstained with safranin.
2. What is the difference between a differential and simple stain
a. Prep smear the same
b. Methylene blue, crystal violet or safranin can be used as primary stain on simple
c. No alcohol or counter stain is used.
3. What role does a spore play in the life cycle of a bacillus
a. The spore is the means to survival for organisms as it allows them to survive long periods of drying, high temperatures, and exposure to many different toxic chemicals.
4. why is acid alcohol used in the acid fast stain and not plain alcohol
a. the stain depends on the resistance to the stained organism to be decolorized by acid alcohol.
5. why will it be difficult to gram stain mycobacterium.
a. The lipid cell wall is wax like and resistant to staining. Gram stains do not tell you anything about the organisms acid fastness. Either heat or concentrated solutions of dye need to be applied in order for the stain to penetrate the lipid cell wall and reach the cell cytoplasm
6. will the presence of a spore have any influence of the ability of a cell to stain gram positive or gram negative
. No.
7. are bacillus and clostridium positive or gram negative
a. Clostridium is positive
b. Bacillus is positive and negative. But species named bacillus are positive. Bacillus means rod shaped.
1. why is it important to know which antibiotic and what concentration of that antibiotic will inhibit the growth of which organism.
a. Not all antbiotics and concentrations work the same on all bacteria. Knowing with and how much to use provides the doctor with the informatio0n necessary to control an infection
2. list at least three reasons why it is important to know what disinfectant and what concentration will inhibit or kill a bacterium.
a. Not all organisms are sensitive to all antibiotics, nor are all antiseptics/disinfectants equally effective
b. One concentration will not kill the organisms but if the concentration is increased, the organism may be killed or at least growth my be inhibited
c. knowing with and how much to use provides the doctor with the information necessary to control an infection
3. what is the difference between biocidal and biostatic
a. Biocidal will kill the organism
b. Biostatic will inhibit the growth of the organisms.
4. What is the difference between an antibiotic and an antiseptic relative to their use
a. Antibiotic kill/control the bacteria by disrupting growth.
b. antimicrobial substances that are applied to living tissue/skin
1. What is an acid/ base indicator
a. An indicator that will change color as the acidity level goes up or down. Exmp. Phenol red
2. What acid/base indicator were used in these experiment
a. Phenol Red
b. Litmus
3. What does the acid/base indicators used in these experiments specifically tell you about the test results
a. Generally acid is produced in fermentation type reaction in carbohydrate dissimilation
b. Oxidation can cause and acid by product but generally not in significant amounts
4. Name at least two different acids produced during metabolism
a. ACETIC ACID
b. LACTIC ACID
7. what amino acid is used in the test for hydrogen sulfide production
a. cysteine
10. why is it necessary to overly one of the tubes in the O?F experiment with mineral oil?
a. The test is whether or not an organism will grow in the presence of oxygen. Mineral oil creates a barrier that prevents oxygen in the atmosphere from mixing with the organism. Identifying it as an aerobe or facultative anaerobe.
12. Why is it important to read some reactions within 24 hours, 72 hours and with some it is not as time critical.
a. Some reaction are faster than others. Enough time needs to be given to allow for the process to happen
b. Some reactions such as the carbs will reverse so you must read right at 24 hrs.
2. what is the origin of antibodies
a. T cells are a major component of cell mediated immunity
b. B cells are a part of the antibody mediated immunity.
c. If an antigen is a soluble substance such as a protein, the b cells will produce antibodies against the antigen.
1. Carbohydrate Metabolism
a. The metabolism of simple carbohydrates. Exp glucose, sucrose, fructose. By products. Are ACETIC ACID, LACTIC ACID, and gases CARBON DIOXIDE AND HYDROGEN.
b. Acid/base indicator is PHENOL RED. Red at pH 8.5 and yellow at pH6.9
c. Gas tube is a durham tube
2. Starch Hydrolysis
a. Exoenzyme is an hydrolytic enzyme that cleaves the bonds that hold subunits together.
b. Starch is a complex polysaccharide. Amylase is responsible for starch hydrolysis.
c. Results, clear zone around colony within seconds after the addition of adding iodine.
3. Casein Hydrolysis
a. Proteases is the exoenzyme that breaks down proteins
b. Caseinase breaks down the milk protein casein making it more transparent
c. May be very fast in some organisms, and slow in others. Read plate over a 1 week period
4. Lipid Metabolism
a. Lipases is the exoenzyme
b. As lipids are hydrolyzed, clear zone will occur, clearing the plate.
5. Gelatin Hydrolysis
a. Gelatinase is the exonzyme
b. Incubate for 4 days. Gelatin is hard to break down. Place in frig before reading.
c. If gelatin is hydrolyzed, it will not re-solidify
6. Litmus Mik
a. Contains both sugar lactose and protein casein.
b. Phenol red is added to observe acid and gas production.
c. Peptonization aka protein hydrolysis.
d. Read results at 24, 48, 72 and 1 week
i. Curd production- when the acidity of the medium changes enough to cause protein to precipitate out of the tube. May be hard or soft.
ii. Reduction of litmus- Litmus is also an oxidation reduction indicator. If oxygen is removed by the reducing action of the bacteria, the litmus is changed from purple to white. Starting from the bottom and rising. Most cases there will be a small purple ring at the top were the litmus if being reoxidized by the atomosphere.
iii. Peptonization aka protein hydrolysis. Organisms that have active proteolytic enzymes will break down and the medium will clear up
iv. Acidic reaction: turns pink if acid is generated.
v. Basic reaction: if turns blue than basic reaction. This indicates that the amino acids in the milk are being broken down.
7. Sulfide-indole-motility SIM Media
a. Used to identify the enterobactericacea by detecting sulfide production, motility and indole formation
i. Sulfide will be dark in color. Some sulfur containing amino acids like cysteine liberate hydrogen sulfide.
ii. Motility- glowth away from the center stab line. Feathers out due caused by the organisms flagella
b. Incubate the medium for at least 24 hours
8. Catalase Test
a. Catalase is a common enzyme found in nearly all living organisms. Will break down hydrogen peroxide.
b. Add hydrogen peroxide. If bubbles, then catalase is present
9. Indole
a. Nitrogen containing compound formed from the degradation of the amino acid Tryptophan.
b. Tryptone is used instead of tryptophan.
c. Indole/nitrate broth used for both the indole and nitrate reduction test
d. add 15 drops of kovac’s reagent into indole. If it turns red, then test is positive for indole. Note the red should be floating on top
10. Nitrate reduction
a. Anaerobic respiration by the enzyme Nitrate Reductase to reduce nitrate to nitrite.
b. Some bacteria can also reduce the nitrite to nitrogen gas
c. Two solutions. Sulfanilic acid and Alpha-napthylamine aka Nitrite A solution and Nitrite B solution
d. If red than positive for reduction to nitrite
e. If no change in color. Negative for nitrite but still may have produced nitrogen gas
f. Add zinc dust to confirm the presence of nitrogen gas. If turns red after the zinc dust then confirmed the test result is negative.
g. If no color change after the zinc, then positive for reduction of nitrate to to nitrogen gas
11. Citrate Utilization-
a. ability to use citrate as a carbon and energy source, which can distinguish certain gram negative bacilli.
b. Simmons citrate agar, if positive then the organism produces citrase.
c. Also may change the medium from green to blue, alkaline reaction
12. Methyl Red
a. Methyl red and voges proskaur test are used to indentify gram negative bacilli
b. Incubate for at least 72 hours.
c. Add 10 drops of methyl red.
d. If turns red, then positive for mixed acid fermentation.
13. Voges Proskaur
a. Add 15 drops of both barrits A and Barritts b. solution. Mix to add oxygen.
b. Take 30 minutes shaking periodically
c. Will turn red to indicate the production of acetoin.
d. possitive test shows pyruvic acid into neutral producs like acetylmethylcarbinol acetoin, and carbon dioxide.
14. Oxidation
a. These tests evaluates the metabolism of glucose in the presence and absence of oxygen.
b. Both solution contain glucose and Bromothymol blue indicator which will indicate if an acid reaction has occurred.
c. Can also observe the motility of the organism.
d. Incubate for 24-48 hours.
e. Color change indicates a pH shift. Resulting in a positive reaction.
f. If only the oxidation test positive, then organism is a strict aerobe
15. Fermentation
a. Same as oxidation but with mineral oil added.
b. If both turn yellow, the organism is a facultative anaerobe
Durham Tube
glass tube to indicate gas byproduct.
Name of taxonomy guides
Bergeys determinative manuals.
test for anti odys
Ouchterlony