Micro pract 2 Flashcards
What’s a great test for differentiating the gram - bacilli?
IMViC test
IMViC stands for what?
- indole - methyl red - vogues- proskauer - citrate utilization
Indole is a waste product of what?
tryptophan breakdown
Indole is detected in what type of media?
SIM media
What does SIM media test for?
sulfur reduction, indole, motility
How is sulfur reduction, indole and motility detected?
- sulfur reduction, H2S gas + ferric sulfide gas - indole by the red regent layer - motility by the turbidity
What is added to the SIM media to detct indole by forming a red reagent layer?
Kovac’s reagent
Methyl Red is what type of indicator? what pH does it detect?
pH indicator -at or below 4.0
In the methyl red test an organism that utilizes glucose will undergo what?
mixed acid fermentation
In the methyl red test if an organism goes under mixed acid fermentation will it be methyl red positive or methyl red negative?
methyl red positive
What is color is positive methyl red test? What color is negative methyl red test?
positive methyl red test = red negative methyl red test = yellow
From left to right name the results of this methyl red test
+ , - , control
In the Voges- Proskauer test organisms convert glucose to what two end products?
acetoin and butendiol
In vogues proskauer when glucose converts to acetoin and butendiol, is it VP negative or positvie?
Vogues proskauer postivie
Adding VP reagents A&B will detect what? what color does it turn when it’s positive?
VP reagents will detect acetoin by turning RED
From left ot right name the results of this vogue proskauer test…
What’s the purpose of citrate utilization?
to see if an organism can utilize citrate as a sole carbon source
If an organism lacks citrate permease in the citrate utilizaiton test what happens?
lacking this enzyme organisms cannot permeate into their interior
What is the result of Growth and Blue, growth and green, and no growth and green in the citrate utilizaion test?
growth and blue = +
growth and Green = +
no growth and green = -
Does citrate utilization require oxygen to grow?
yes it does
Name the results of this citrate test from left to right?
left - , right +
Name the four tests to test STAPH ?
coagulase test, catalase test, mannitol salt agar, novobicin susceptibility
What is coagulase?
an enzyme that closts blood plasma
What type of organism produces coagulase?
Pathogenic Staphylococcus aureus
Catalase is an enzyme that does what?
Degrades H2O2 –> H20 + O2
What type of organism is postive for catalase test, how about negative?
Staphylococcus are POSTIVE, Streptococcus is NEGATIVE
What causes the bubbles in the catalase positive test?
Oxygen gas (O2)
What is the result of this catalase test?
positive
What is the result of this catalase test?
negative
In Mannitol Salt Agar mannintol is fermented to what by what?
mannintol is fermented to acid by some pathogenic staph like S. aureus
Mannintol in mannintol salt agar is selective or differential ?
Differential
In Manintol Salt agar the salt is what percent NaCl?
7.5 % NaCl
The 7.5% NaCl in Mannintol salt agar does what to Staph?
inhibits all but hte salt- tolerant Staph
The 7.5% NaCl in Mannintol salt agar is selective or differential?
differential
The Phenol Red in Mannintol Salt Agar is a pH indicator that turns YELLOW if what happens?
if mannintol is fermented to acid
The Phenol Red in Mannintol Salt Agar is a pH indicator that turns RED if what happens?
if mannintol is not fermented
Explain the results of this mannintol salt agar plate.
left = yellow = mannitol fermented
right = red = mannitol not fermented
Name the three types of tests used to detect strep?
hemolysis on blood agar, Growth in 6.5% NaCl, Bile esculin
Hemolysis on blood agar is useful for differentiating what speices
steptococcus
Beta hemolysis is what?
complete breakdown of RBC resulting in clear zones around growth
Alpha hemolysis is what?
incomplete breakdown of RBC resulting in greenish zone around growth
Gamma hemolysis is what?
no breakdown of RBC and no change in medium around growth
Explain results of this test?
left = beta
top = gamma
right = alpha
Growth in 6.5% NaCl is used for differentiating what?
enterococcus from non enteric strep. ONLY ENTEROCOCCI will grow in 6.5% NaCl
Explain the result of this 6.5% NaCl
Left = negative control
middle = positive (enterococci)
right = negative
Bile esculin hydrolysis is used for differentiating what?
Group D enteric streptococci from non enterics
What does the Bile do in bile esculin hydrolysis?
inhibits non enteric organisms
What does the Esculin do in bile esculin hydrolysis?
fermentable carbohydrate
What does the Azide do in bile esculin hydrolysis?
Inhibits gram negative
What does the ferric citrate do in bile esculin hydrolysis?
color indicator that turns dark brown if esculin is hydrolyzed
Explain the results of this bile esculin test
left negative control, middle positive for esculin hydrolysis, right negative
Triple sugar iron medium contains what?
glucose, lactose, sucrose, protein and iron salts
What happens to the sugars in the triple sugar iron medium?
fermented to acids
What happens to the proteins in the triple sugar iron ?
can be catabolized to alkaline amines
What happens to the sulfur in the triple sugar iron medium?
can be reduced to H2S
In the triple sugar iron test pehnol red is what color when acidic…what about basic?
acid = yellow
alkaline = pink
The iron salts detect H2S gas in triple sugar iron and turns what color?
black
Urease is an enzyme that hydrolyzes ___ into what two end products?
hydrolyzes urea into ammonia and carbon dioxide
What is the pH indicator added to the urease test and what does it detect?
phenol red is added to detect ammonia
What color is the urease test when + and what is it when - ? what does this mean?
Urease + = pink
urease - = yellow
POSITIVE means that urease enzyme is present
From left to right name the results of this urease test?
positive, negative control, weakly positive, negative
Amylase is an ____ that hydrolyzes startch into what?
amylase is an exoenzyme, hydrolyzes startch into simple sugars
What is added to the startch hydrolysis test and what does it detect?
iodine is added to the starch hydrolysis test… It detect starch
Name the results of this starch hydrolysis test left ot right and describe why it happens…
left letter b: negative = amylase not secreted starch not broken down
Right letter a = positive = amylase secreted broke starch down
Starch hydrolysis is a common cause for what?
food borne illnesses
DNase is a ____ that degrades what?
an exoenzyme that degrades DNA
How does DNase work?
breaks phophodiester bonds. releasing free nuclotides
What is added to the DNase test? and what does it indicate
methyl green: DNA indicator
Explain this DNase test..what do the results mean
Left positive = DNase degreded DNA
right negative = DNase not present
The oxidase test is used ot differentiate what two families? and what are the results of those two families?
Enterobacteriacae (oxidase -)
Pseudomonadacea (oxidase +)
Oxidase positive must have what? How about the oxidase negative? (air)
oxidase positive is aerobic/ microaerophillic rods
oxidase negative is faculatative anerobic rods
Oxidase is a ____ and does what to electrons. What does this action form?
enzyme, transfers electrons forming water
What is added to the oxidase tst to detect the oxidase enzyme? What are the colors associated with positive and negative?
oxidase reagent is added.
positive = purple
negative = yellow
Explain the results of this oxidase test..
Left is postive = purple (Pseudomonadaceae)
right is negative = yellow (enterobacteriacae)
Novobiocin is a _____ that is used to distinguish certin members of the ____ genus?
its an antibiotic used to distinguis certin members of the staphylococcus genus
Which species of the Staphylococcus genus is the novobicin test especially good in differentiating?
- S.saprophyticus* ( N - resistant)
- S. epidermis and S. aureus* (N susceptible)
In the novobiocin test greater than 16 mm = what?
less than 16mm = what?
greater than = resistant
less than = susceptible
Explain the results of this novobicin test..what do those results mean?
left is resistant = S. saprophyticus
right is susceptible = either S.aureus or S. epidermis
In the decarboxylase test what is removed? what is this group removed by? (enzyme)
Decarboylase enzyme removes the COOH (carboxy acid) group from A.A or similar substrate
What is produced when lysine and ornithine is decarboylated? Are these end products basic or alkaline?
Lysine decarboxylated to cadaverine
Ornithine decarboylated to putrecine
- both products are alkaline amines
In the decarboxylase test what 3 thingsdoes the medium contain? which one is the pH indicator
specific amino acid, glucose, brom cresol purple (a pH indicator)
What is added to the decarboylase test to promote an anerobic enviornment?
mineral oil
In the decarboxylase test postive = what color, negative = what color?
Positive and negative mean what?
yellow = negative, glucose was fermented to acid
purple = positive, the amino acid was decarboxylase to an alkaline amine
What are the four tests used under decarboylase? (MIO)
motility
indole
orthithine decarboxylase
lysine decarboxylase
— results are the same (yellow/ purp)
Explain the results of this test.. (the middle is control)
postive left, control, negative
Phenylalanine is an _____.
amino acid
Phenylalanine deaminase is an _____. What does Phenylalanine do?
enzyme…removes the amino group from phenylalanine
If phenyllalanine deaminase removes the amino group what is the end product?
Phenylpyruvic acid
What is added to the phenylalanine deaminase test and what does it detect? positive it turns waht color negative what color?
Ferric chloride (FeCl3) detects phenylpyruvic acid
postive = green
negative = yellow
Explain the results of this phenylalanine deaminase test…tube in middle = control
Left postive for phenylalanine deaminase right is negative
In the Phenol Red carbohydrate test the phenol red is what? What color does it change when acidic vs alkaline?
Phenol red is a pH indicator, turns pink when acidi
yellow when alkaline
What is the carbohydrate in the phenol red carbohydrate fermentation test? what does the durham tube do?
a fermentable sugar, durham tube traps gas
How is acidic, alkaline and formation of gas represented when reporting results for the phenol red carbohydrate fermentation test?
yellow = positive= acidic= A
Pink = negative = alkaline = K
Gas = G
Nitrate reduction is to see if an organism can what?
reduce nitrate to nitrite or even boyone the nitrite state
Nitrate reduciton is one form of what type of respiration?
anaerobic respiration
In nitrate reduction, what’s the difference between entreric organisms vs non enteric organisms?
enteric organisms have nitrate reductase and can reduce nitrate to nitrite in a single step
non- enteric organisms have enzymes that all them to reduce nitrate beyond the nitrite state
How is nitrate reduction tested? steps
NO3 (nitrate) broth is inoculated with test organism, incubated then tested to see if nitrte has been reduced
What is added to the nitrate reduction test to see if nitrite is present? if positive the color will be?
nitrate reagents A & B.
will be red if positive
If the nitrate reduction test has not turned red after the reagents were added to it what will be the next step? why?
zinc dust is added to see if nitrite was reduced to beyond nitrite step or if nitrate reduction just isnt present.
