Flashcards in Lab Practical/final Deck (127):
In the indole test, the activity of what enzyme is tested for?
If there is a positive indole test, what amino acid must have been present?
What is tested for in the Methyl Red Test?
What enzyme is present in a positive methyl red test?
If a pure culture has a positive methyl red test and butanediol production wa also tested for, would you expect a positive or negative result? Explain
Negative. If Methyl Red was positive, you would have a negative butanediol.
What is tested for in the Vogues-Proskauer Test?
Name three media stabbed when they're inoculated.
Citrate slant, SBA, TSIA
Why does the agar turn blue in a positive Citrate slant?
Bromothymol Blue indicating the pH increased.
Name two bacteria which give a positive result on the citrate test.
Enterobacter cloacae and Salmonella enteritidis.
If a Proteus culture is inoculated into a urea broth and a red-purple color is observed after 20 minute incubations at 37 degrees celsius, Is this a positive test or a negative test?
Wat enzyme must be present for a positive urea reaction?
E.coli, Staphylococcus aureus, and Enterococcus faecalis display what oxygen requirement?
Name an anaerobic organism that was discussed in lab this semester.
Describe Brownian Motion.
Vibration of cells from activity of water molecules.
The oil immersion objective provides what total magnification?
Which part of the microscope has the purpose of focusing the radiation from light onto the specimen?
What type of microscope is used in this lab?
What does parfocal mean?
same focus position is correct for all objectives.
Name a structure that is extremely heat resistant.
What is the solution used to clean the slides?
How many times is a smear from a liquid culture heat fixed?
How many minutes is a slide with a smear allowed to air dry?
How many times is the loop flamed when a quadrant streak is performed?
Name the only eukaryote that was encountered in this lab.
yeast, Sacromices cervicia
Name the bacteria that produces a red pigment.
What is the name of the red pigment produced from S. marcescens?
What is the name of the test method for antibiotic sensitivity? What is it made of and its pH?
Kirby-Bauer-Mueller Hinton agar (7.2-7.4 pH, thick)
What is the test medium for the antibiotic sensitivity testing?
Moller-Hinton agar (MHA)
What is measured in the antibiotic sensitivity testing?
Zone of inhibition
What medium is use to test for hemolysis?
Sheep blood agar
WHat is the equation for determining the doubling time?
When the first sample was taken, the cell concentration was 5 x 10^5 cells/ml. When the second was taken after 90 min, the concentration was 4*10^6 cells/ml. What is the doubling time?
What test uses Kovacs reagent?
What does a negative indole test look like?
No bright red ring, yellow.
A positive methyl red test demonstrates what?
acid production during glucose fermentation.
Methyl red test: orange + or -, yellow + or -
What test contains pH indicator bromothymlol blue?
What is the original color of the agar in the citrate test?
Bacteria can be distinguished based on surface differences. What are they called?
What are the step of Gram Staining?
1) crystal violet for 30 seconds
3) iodine 30 seconds
5) ethyl alcohol until no color
6) safranin for 45 seconds
7) wash and blot
What is the standard unit of measurement?
How do you calibrate a microscope?
Superimpose ocular and stage units
Look for next point where they coincide
count both divisions.
Use calibration equation
What is the calibration equation?
SU/OU * mm/SU=mm
What is the dilution equation?
mL of suspension/Total volume *Initial conc.
How does Gram staining work and why?
The thick walls of Gram positive cells dehydrate when exposed to alcohol. This causes the cell wall to close any spaces making it impossible to dissolve the crystal violet iodine complex.
What does a mordant do?
Fixes they dye
From the beginning to end, what are the parts of a growth curve?
lag, log, stationary, death
What are the 3 counting methods to determine cell concentration? Explain them and why they are good/bad.
Direct count: count directly the number of cells on a microscope slide. You cannot distinguish live cells from dead ones.
Mass measurement: weigh them, Its really hard to way such small things. Use light scattering devices (spectrophotometer).
viable count: examines living cells by looking at separated colonies from pour plate procedure.
What are the components of the spectrophotometer? Explain.
Light source: light that shines on specimen tube.
sampel chamber: well for sample tube
phototube: converts light into electrical current and moves the needle.
What are the three ways to determine motility? Explain
1. Wet mount: used with a phase-contrast microscope. fastest and easiest, will also tell you about size, shape, and arrangement.
2. Culture method:Suspected to be a pathogen; use semisolid and stab, motile bacteria will move through media and you will see turbidity around the track.
3. Hanging drop: long observation of livig organisms, but depth of focus is limited because of the large drop-use depression slide. Close diaphragm to limit light.
What is true motility?
motion of individual cells over several body lengths.
What is mode of action and what are the 5 modes of action?
Metabolic target within the cell it harms
1. cell wall synthesis
2. membrane permeability
4. protein synthesis
5. enzymatic activity
What are the 3 reactions of antibiotics? explain
1. Bacteriostatic: total count and viable count remain the same, when antibiotic is removed the bacteria will multiply.
2. Bactericidal: Bacteria killed, but cells remain intact. Total count is same, but viable count diminishes.
3. Bacteriolytic: Bacteria killed by cell lysis, total count and viable count diminish.
What is the zone of inhibition? What happens at the end?
It is the area on a plate where growth of an organism is prevented by an antibiotic. At the end of zone, antibiotic is diluted to MIC.
What is the minimum inhibitory concentration?
it is the concentration of antibiotic to inhibit bacterial growth.
What are the 6 antibiotics used in lab?
4. Polymyxin B
what does pyogenic mean and what 2 organisms that we studied are?
Staphylococci and Streptococci
What is the morphology of Staphylococci? why?
irregular clusters, cells divide in more then one plane and don't separate after division.
What is the difference between differential and selective media?
selective media favor the growth of some bacteria and disfavor that of others. Differential media results in different appearances of different groups of bacteria.
What is an SBA plate?
trypticase soy agar with 5% sheep blood.
What does Non-hemolytic mean?
Bacteria that grows on SBA without damaging red blood cells.
What is alpha hemolytic? What does it look like and why?
partial damage of red blood cells, green or brown color around colony from leakage of potassium.
What is beta hemolytic?
complete destruction of red blood cells in area around each colony. Forms a clear zone
What is in an MSA plate?
beef extract, peptone, 7.5% NaCL, mannitol, and phenol red pH indicator.
What is the CAMP factor?
An extracellular material produced by Streptococcus agalactiae
What does the CAMP factor do?
enhances the ability of staphylococci to lyse red blood cells.
What is the CAMP test?
Streptococci is inoculated on the same plate with a perpendicular streak to the streak of staphylococci. There should be a clear zone around the staph streak and pale red around the strep. If strep is positive for CAMP, than clearing of Staphylococci will be in shape of arrow.
What is monotrichous?
single polar flagella
what is amphitrichous?
flagellum on each end
what is lophotrichous?
multiple flagella on same spot
what is peritrichous?
flagella around entire surface
Define growth rate
time needed for the population of bacteria to double.
What are the y axis and x axis in a standard curve?
What are the x and y axis on the growth curve?
Appearance of Serratia marcescens
Red from prodigiosin at room temp.
off what at 37
Appearance of E. coli
off white at RT and 37
Appearance of Staphylococcus aureus
opaque yellow to white at RT and 37
what is the motility of Micrococcus luteus
What is the motility and structure of proteus vulgaris?
motile and peritrichous
Where can staph be found?
Nasal membranes, hair follicles, skin.
How large is staph?
what is the hemolysis type for staph?
Is staph catalase (+)?
What does staph ferment?
What does staph produce, and what does it do?
alpha toxin, lyses red blood cells in blood agar.
What is MSA and what is it selective for?
Mannitol salt agar, staph aureus.
What is the coagulase test, what produces it?
An enzyme produced by staph aureus. Clots the blood plasma.
How do you know when something is positive for coagulase?
If its positive the clot will be at the bottom of the test tube.
What is the catalase test and what does catalase do?
Breaks down H2O2 to water and oxygen. If you put H2O2 in tube and it bubbles, the it is positive.
What organisms are catalase positive?
staph and micrococcus
What organisms are catalase negative?
Where are streptococci found?
What are lancefield groups?
categorization scheme for strep.
What does CAMP do? What is the reaction?
Enhances ability for staph to lyse red blood cells. paling of red color around strep.
What is Bacitracin susceptibility?
Strep pyogenes is susceptible to antibiotic bacitracin.
What is Optochin?
test strep. pneumoniae with hydrocuprein hydrocholoride.
What is bile soluble?
streptococcus pneumoniae, it will disolve in bile.
If organism is catalase positive...
it ferments mannitol and produces alpha toxin.
Why is clot formation beneficial?
it protects phagocytes from destroying cells.
What are coliforms?
like e. coli, indicator organisms, indicate sewage contamination.
What are serotypes?
distinguish based on surface types.
If something can ferment lactose what does it look like?
where is salmonella/ shigella found?
what will e coli look like on emb?
purple w black
In carbs what color is - for fermentation?
red, otherwise yellow.
what are the imvics for e coli?
What are the imvics for e aerogenes?
What are the imvics for e cloacae?
If citrate +?
uses citrate as only source of carbon.
urea hydrolysis distinguishes what?
proteus; hydrolyzes urea through urease
What is the reagent in indole? what is +,-
Kovacs, red+ yellow -
what is the reagent in methyl red? what is +,-?
methyl red, red +, yellow -
What is the reagent in vogues proskauer? what is +,-?
Barrits reagent, pink+, black -
The color of a positive citrate is? negative?
Positive urea is? negative?
what organisms produce endospores?
Which organism are acid fast?
Enterococcus faecalis what air?
clostridium sporogenes air?
Bacillus subtilis air?
staph aureus and e. coli air?
What 2 organisms are beta hemolytic?
strep pyogenes and agalactiae
What 2 organisms are alpha hemolytic?
strep pneuminiae and viridian
what org are MR +?
e coli, salmonella, proteus
what orgs are VP +?
what orgs are citrate +?