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41 Cards in this Set
- Front
- Back
What test would you use to determine if the organism is capable of breaking down starch to maltose? What enzyme accomplishes this? |
Enzyme- alpha amylase |
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What is the general procedure for the amylase test?
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Clearing = positive |
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What is the bile esculin test? What percent bile is the medium?
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Determines organism's ability to hydrolize the glycoside esculin to esculetin and glucose. Medium is 40% bile. |
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Why is the bile esculin test basically two tests?
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1. Growth on bile 2. Hydrolysis of esculin *some streptococci that can split esculin can't tolerate such high bile |
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General bile esculin test procedure?
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Pos- half+ tube is black/brown Neg- less than half is black brown |
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What test determines ability of an organism to degrade a specific carbohydrate in basal medium? What does it produce? ( 2 things)
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1. Acid (pos, color change) 2. Acid with visible gas |
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Carbohydrate Test procedure?
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Fermentation pos: any yellow color, neg: red, pink, orange Gas: pos: significant bubbling in semi solid medium. neg: no excessive gas bubbles. |
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Catalase test- what does it test for, what is a positive?
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Tests for enzyme catalase. Positive is bubbling, |
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Catalase test procedure?
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*Nitrochrome wire |
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What tests for the hydrolysis of DNA?
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DNAse Test |
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DNAse Test: Methyl Green indicator is stable at what pH? Does the pH of the agar increase or decrease when hydrolysis of DNA occurs?
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Hydrolysis causes drop in pH |
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DNAse Test procedure?
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Pos- clearing around areas of growth Neg- color of agar is the same, no hydrolysis |
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What tests for hydrolysis of gelatin? What is pos and what is neg result?
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Gelatinase Test Procedure?
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Obtain two solid gelatin butts. Heavy inoculum, stab to depth of 2". Use other tube as control. **DO NOT SHAKE, if gelatin and medium mix when warm, may get false pos. |
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What type of plate would you use for a Hemolytic Reaction Test?
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Sheep Blood Agar (SBA) |
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What enzymes are you testing for in Hemolytic Reaction Test? What do they do?
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Hemolysins. Lyse red blood cells. |
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What 3 types of hemolytic activity can you see in the hemolytic reaction test? What does each type indicate?
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Beta- complete lysis, reduction of released hemoglobin. Clear zone around colonies. Gamma- no hemolytic reaction, no change of medium **Check only around isolated colonies. |
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What test imitates the environment of the skin? What bacteria does it typically test for? |
Mannitol Salt Agar Test. Staphylococcus species- indicated by any significant growth. |
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Mannitol Salt Agar Test procedure? Pos/neg indicators?
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Streak MSA plate with light line of inoculum from pure culture. Incubate. Pos- growth; yellow color. yellow indicates acidic pH, product of fermentation Negative- growth/no growth; red or orange |
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What tests for an organism's ability to reduce nitrate to nitrite, then to free nitrogen gas? What serves as an electron acceptor?
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Nitrogen in nitrate serves as electron acceptor |
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Test procedure of Nitratase test? |
Innoculate nitrate agar slant with pure culture, heavy inoculum. Add 2-3 drops of both Reagent A and B. Can add small amount of zinc powder if no color occurs right away. |
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Pos/Neg results in Nitratase Test? |
Negative: pink to dark red after adding zinc (nitrate is present, but not reduced by organism Positive: no color (reduced all nitrate to nitrite and then to N2 gas, which escaped the tube |
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Which reagent in the Nitratase Test is potentially carcinogenic?
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Reagent B: 0.6% N, N-dimethyl-alpha-napthylamine in 30% acetic acid |
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What is Novobiocin? What does the Novobiocin Disc Test detect? |
Novobiocin is an antibiotic. Tests detects organism's susceptibility. |
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Novobiocin Test procedure? |
Streak BHI plate, turn 90 degrees and streak again. Place disk in middle. Incubate, observe. |
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What test would you use to determine if bacterium makes enzyme betagalactosidase?
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1% ONPG Test |
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(ortho-nitrophenyl-galagopyranoside) |
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What part of the bacterial cells does the Optochinin Disc Test target? What bacteria is it used mainly for?>
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Fragility of bacterial cell wall. Streptococcus pneumoniae (sens) and other Strep species (nonsens) |
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Optochin Test procedure?
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Single pure colony. Innoculate a SBA plate., Streak entire plate.. MUST USE SBA because colony is fastidious. Apply disc, incubate, observe. |
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What test determines the presence of oxidase enzymes? What is an example of an oxidase enzyme? |
Oxidase Test. Cytochrome c oxidase. |
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Oxidase Test procedure?
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pos- purple color in 20seconds. Saturate slide with Kovac's oxidase reagent. Neg- do not change color in 20seconds. |
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What type of bacteria are oxidase negative?
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2. All Enterobacteriaceae |
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Why can't you do the oxidase test on bacteria on media with glucose |
Glucose fermentation inhibits oxidase enzyme activity, could give false negative. |
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What is the procedure for oxygen requirement test?
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Use thioglycolate tube, use need to stab culture down to the bottom. Incubate. |
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What type of growth will a facultative anaerobe produce? A microaerophile?
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Microaerophile- Band of growth near top, but not touching surface. |
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Penicillin Test |
Same as other disc tests |
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What tests an organism's ability to tolerate various osmotic concentrations?
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Salt Tolerance Test
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Test procedure for Salt Tolerance Test? |
pos- turbidity negative-no turbidity |
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Urease test determines organism's ability to break urea down into what? (3 things)
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Carbon dioxide, water, ammonia |
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What is the urease test primarily used to distinguish between? |
Urease+ proteeae from other Enterobacteraceae |
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Urea Test procedure? |
Use heavy fresh inoculum. Streak entire surface of slant. Incubate. Observe color change at 6hrs, 24 hrs, and every day up to 6 days. pos- bright pink, any pink |