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64 Cards in this Set

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  • Back
What is resolving power?
the ability to distinguish between two points
What is human body temperature?
37C
What color would a human cell be in a gram stain? Gram + or - ?
Red, gram -
What is the decolorizing agent in a gram stain?
ethanol
What is the decolorizing agent in an acid-fast stain?
acid alcohol
What diseases are diagnosed using the acid-fast procedure?
Mycobacterium caused disease.
tuberculosis, leprosy, and other pulmonary diseases
What is the purpose of the paper in the acid-fast stain?
Keeps it from drying out
How would the appearance of a 24hr bacillus culture and a 72hr culture differ? How do you account for this?
spores will be released in the 72hr culture, as times goes by they produce waste and then die off and produce spores.
What genus of organism seems to be the one that can lower the pH enough to dissolve tooth enamel?
streptococcus
What is the indicator used in the snyder test?
bromcresol green
What is the color of the control in the synder test?
green
What color will the indicator turn if the pH becomes more acidic?
yellow
Why are bile salts and crystal violet added to MacConkey agar?
they inhibit gram + organisms
What chemicals are added to EMB to prevent gram + growth?
Eosin, methylene blue
Is MacConkey agar selective or differential?
both
Is EMB selective or differential?
both
Is the blood agar used for the hemolysin test a differential or selective medium?
differential
What does TSI stand for?
triple sugar iron
Which nutrient is in short supply in a TSI slant
glucose
What color will the slant and butt turn if the organism can use glucose but not lactose?
red slant, yellow butt
What happens when an organism uses peptones in the TSI agar?
Ammonia is produced, pH is raised. Changes to dark red. When it runs out of glucose it starts aerobically eating peptones on top of slant
What happens to the color of the slant and butt if the organism can ferment lactose in TSI agar?
Both yellow
Why would the tube look black in a TSI agar slant?
Organism produces H2S gas, reacting to make FeS which is black
What is the reaction for the production of black in a TSI agar tube?
H2S + Fe ==> FeS + H2
Why should you not analyze results too early in a TSI test?
Organism may have only eaten glucose and will be yellow, hasnt had time to go on to other things yet.
Why should you not analyze results too late in a TSI agar test?
Organism can eat all sugar and move to proteins, turning tube completely red.
What is the exoenzyme in starch hydrolysis?
amylase
What is a positive test that casease exoenzyme is secreted?
clear halo around organism
What organic compound is gelatin?
protein
Why is agar used as a solidify agent instead of a gelatin?
agar is not nutritive
what would you find in the liquid of hydrolyzed gelatin
amino acids
nutrient gelatin is incubated at 35C. What would have to be done to determine hydrolysis after incubation?
Cool it down to resolidify
what is a positive test for lipid hydrolysis?
makes clear halo
Is the carbohydrate test selective or differential?
differential
What is a positive test for fermentation?
yellow
What is a negative test for fermentation?
red
Why does the indicator turn yellow when fermentation occurs?
sugars ferment and make acid, changes indicator yellow.
What is an alkaline swing?
after 1st 24hr it changes yellow (acidic) after all sugars are used. After 2nd 24hr it changes back to red (alkaline) as it starts using proteins
What is a positive test for urease production?
pink
What is the source of urea in the body?
proteins, amino acids brokedown
What is the formula for hydrogen peroxide hydrolysis with catalase?
H2O2 ==> H2O + O2
In the catalase test, what gas is in the bubbles?
O2
What types of organisms produce catalase?
aerobic
What does CFU stand for?
colony forming unit
Why should hamburger meat be cooked more thoroghly than steak or roast?
hamburger meat has more surface area, which the bacteria grows on. Steak or roast only has the outside of the meat for growing the bacteria.
Is the test for milk a qualitive or quantitative measurement?
quantitative
Milk is considered to be contaminated when the bacteria count rises above ____.
20,000/mL
What range of bacterial colonies on a plate should be used for counting?
25-250
What stain is used in the simple stain? How long is it applied?
Methylene blue. 60sec
What is the primary stain, counterstain and mordant in the gram stain?
Crystal violet
Safranin
Iodine
What color is gram +?
purple
What color is gram -?
pink
What is the primary and counterstain in the acid-fast?
Carbolfuschsin
methylene blue
What are the stains in the spore stain?
malachite green
safranin
What is the name of the agar used in the salival test in experiment #4?
Snyder agar
What is a positive test on MSA agar? Negative?
Yellow
Red
What is a positive test on MacConkey agar? Negative?
Red/pink
agar color, white/colorless
What is a positive test on EMB agar? Negative?
Red, if alot, shiny-green metallic
agar color
What is the name of the test in lab #7
Antimicrobial susceptibility test
What is the name of the agar used in the antimicrobial susceptibility test?
mueller-hinton agar
What are the organisms used in the hemolysis test? What were their results?
E. coli - gamma-hemolysis
S. pyogenes - beta-hemolysis
Throat - alpha-hemolysis
In starch agar test what is a positive test? Negative?
Clear halo around organism where iodine doesnt stick
What is the enzyme that breaks down milk protein?
casease
What is a positive test for gelatin hydrolysis?
It is liquid when cooled