Term
| What is triple sugar iron agar? |
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Definition
| a rich medium designed to differentiate bacteria on the basis of glucose, lactose, and sucrose fermentation and sulfur reduction |
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Term
| What is TSI agar made up of? |
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Definition
| 3 carbs (glucose, lactose, sucrose), beef extract, yeast extract, peptone, sodium thiosulfate, phenol red, and ferrous sulfate |
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Term
| Why is sodium thiosulfate included in the TSI agar? |
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Definition
| as a source of reducible sulfur |
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Term
| What is the indicator in TSI agar? |
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Definition
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Term
| Why is ferrous sulfate included in TSI agar? |
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Definition
| as a hydrogen sulfide indicator |
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Term
| Why is peptone included in TSI agar? |
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Definition
| as sources of carbon and nitrogen |
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Term
| Why is peptone included in TSI agar? |
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Definition
| as sources of carbon and nitrogen |
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Term
| Why is TSI agar prepared as an agar slant with a deep butt? |
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Definition
| to provide both aerobic and anaerobic growth environments |
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Term
| What is reversion in the TSI agar? |
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Definition
| because glucose is in short supply it is quickly exhausted, lowering the pH and turning medium yellow but then amino acids in medium are broken down, producing NH3 and raising the pH, resulting in a red slant but a yellow butt |
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Term
| What can you conclude from a yellow slant/yellow butt in the TSI agar? |
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Definition
| glucose & lactose and/or sucrose fermentation with acid accumulation in slant and butt |
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Term
| What can you conclude from a red slant/yellow butt in TSI agar? |
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Definition
glucose fermentation with acid production.
peptone catabolized aerobically (in the slant) with alkaline products (reversion) |
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Term
| What can you conclude from a red slant/red butt in the TSI agar? |
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Definition
no fermentation.
peptone catabolized anaerobically and anaerobically with alkaline products.
Not from Enterobacteriaceae |
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Term
| What can you conclude from no change in slant/no change in butt in TSI agar? |
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Definition
organism is growing slowly or not at all.
not from Enterobacteriaceae |
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Term
| What can you conclude from black precipitate in the TSI agar? |
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Definition
| sulfur reduction. (an acid condition, from fermentation of one or more sugars, exists in the butt even if the yellow color is obscured by the black precipitate |
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Term
| What can you conclude from cracks in or lifting of agar in TSI agar? |
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Definition
| gas production has occurred |
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Term
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Definition
| a powerful peptide antibiotic produced by Bacillus licheniformis that inhibits bacterial cell wall synthesis |
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Term
| What is the disc-diffusion method? |
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Definition
a commercially prepared filter paper disc is impregnated with a specific concentration of antibiotic and is place on an agar plate inoculated to make a bacteria lawn
as antibacterial agent diffuses from disc into the agar, a concentration gradient is created, which inhibits susceptible bacteria (zone of inhibition) |
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Term
| What is a positive test in the Bacitracin test? |
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Definition
| zone of clearing 10 mm or greater, organism is sensitive to bacitracin |
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Term
| What is a negative test in the Bacitracin test? |
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Definition
| zone of clearing less than 10 mm, organism is resistant to bacitracin |
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Term
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Definition
| exotoxins produced by Gram-positive cocci which are able to destroy red blood cells and hemoglobin |
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Term
| What is blood agar a mixture of? |
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Definition
| Tryptic Soy agar and sheep blood |
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Term
| What are the 3 major types of hemolysis? |
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Definition
| beta-hemolysis, alpha-hemolysis, gamma-hemolysis |
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Term
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Definition
| an antibiotic produced by Streptomyces niveus that interferes with ATPase activity and the production of ATP |
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Term
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Definition
| an antibiotic that interferes with ATPase activity and ATP production in susceptible bacteria |
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Term
| What is a positive result for the novobiocin test? |
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Definition
| zone of clearing 16 mm or greater, organism is sensitive to novobiocin |
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Term
| What is a negative result for the novobiocin test? |
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Definition
| zone of clearing less than 16 mm, organism is resistant to novobiocin |
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Term
| What is a positive test result for the Optochin test? |
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Definition
| zone of clearing 14 mm or greater, organism is sensitive to optochin |
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Term
| What is a negative test for the Optochin test? |
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Definition
| zone of clearing less than 14 mm, organism is resistant to optochin |
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Term
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Definition
| complete destruction of RBCs and hemoglobin, results in a clearing of the medium around colonies |
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Term
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Definition
| the partial destruction of RBCs that produces a greenish discoloration of the agar around the colonies |
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Term
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Definition
| non-hemolysis that appears as simple growth with no change to the medium |
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Term
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Definition
| hemolysins produced by streptococci |
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Term
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Definition
| an oxygen-labile streptolysin that expresses maximal activity under anaeroboic conditions |
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Term
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Definition
| an oxygen-stable streptolysin that is oxygen-stabile but expresses itself optimally under anaerobic conditions as well |
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Term
| What technique is used to provide a favorable environment for streptolysins on Blood Agar? |
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Definition
| streak-stab technique-plate is streaked for isolation and then stabbed to reduce oxygen concentration of the subsurface environment |
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Term
| What does clearing around growth in the blood agar indicate? |
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Definition
| organism hemolyzes RBCs completely (beta-hemolysis) |
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Term
| What does greening around growth in the blood agar indicate? |
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Definition
| organism hemolyzes RBCs partially (alpha-hemolysis) |
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Term
| What does no change in the medium in the Blood agar indicate? |
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Definition
| organism does not hemolyze RBCs (gamma hemolysis) |
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Term
| What is the Motility Test Medium? |
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Definition
| a semisolid medium designed to detect bacterial motility |
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Term
| What is the agar concentration of the Motility Test Medium and why? |
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Definition
-0.4% (reduced from 1.5%)
-just enough to maintain its form while allowing movement of motile bacteria |
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Term
| Why is a tetrazolium salt (TCC) sometimes added to Motility Test Medium? |
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Definition
| used as an indicator to make interpretation easier |
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Term
When is TCC colorless and soluble?
When is it red and insoluble? |
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Definition
-colorless and soluble when in its oxidized form
-red and insoluble in its reduced form |
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Term
| What is used to inoculate Motility Test Medium? |
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Definition
| a straight transfer needle |
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Term
| What can one conclude from red diffuse growth radiating outward from the stab line in the Motility test? |
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Definition
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Term
| What can one conclude form red growth only along the stab line in the Motility test? |
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Definition
| the organism is nonmotile |
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Term
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Definition
| enzymes that hydrolyze fats |
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Term
| What is the simple fat that is usually used in the lipase test? |
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Definition
| tributyrin oil is most commonly used bc it is the simplest triglyceride found in natural fats and oils |
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Term
| What are triglycerides composed of? |
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Definition
| glycerol and 3 long chain fatty acids |
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Term
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Definition
| to break down tributyrin because it is too large to enter the cell |
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