Lab 3 Flashcards
Streptococcus ID and Isolation
Blood agar was used
What kind of medium is it?
What technique did we use with the plate?
Enrichment and differential
Quadrant Streak Isolation
We swabbed our throats looking for Streptococci
What are the possible results
Alpha: Green area. Reduced hemolysis around colonies Pin head sized.
Possibly Streptococcus mitis / Streptococcus pneumonia
Beta: Clear Zones under and around colony RBC Destroyed Pin head.
Possibly: Staph aureus / Streptococcus pyogenes
Gamma: No hemolysis Larger colonies
Possibly: Staphylococcus epidermidis
Alpha hemolysis: Describe
Possible species
Green area. Reduced hemolysis around colonies Pin head sized.
Possibly Streptococcus mitis / Streptococcus pneumonia
Beta hemolysis: Describe
Possible species
Clear Zones under and around colony RBC Destroyed Pin head.
Possibly: Staph aureus / Streptococcus pyogenes
Gamma hemolysis
No hemolysis Larger colonies
Possibly: Staphylococcus epidermidis
In blood agar why do we stab the agar?
To allow less oxygen to encourage growth of bacteria
Mannitol contains how much sodium chloride
7.5%
What are fomites
Inanimate objects that may contain bacteria
Which species cause Beta lysis ( Clear Zone)
Does this destroy the blood cell
Staphylococcus aurus
Streptococcus pyogenes
Yes
Which species causes Alpha lysis ( Green or brown)
Is this destruction of the RBC
Streptococcus mitis
Streptococcus pneumonia
Partial
Which species causes Gamma lysis(No color change)
Does this destroy it?
Staphylococcus epidermidis
No
What kind of media is Mannitol Salt plate?
How so?
Which type of bacteria were we looking for?
Selective 7.5% NaCl selects for Staphylococcus
Differential: Mannitol when fermented bacteria produce acid which turn pH indicator Phenol red to a Yellow color
What does a Pink / Yellow color on Mannitol Salt Plate indicate?
Pink no break down of sugar
Yellow break down of sugar
Type of bacteria we were looking for in the blood agar experiment with the quadrant Streak taken from throat
Streptococci
Type of bacteria and medium used in the Nose, Formite, and Unknown.
What was the differential process
What was the selective process
Type of medium used
Staphylococci
Breaking down of the sugars (mannitol)
7.5% salt
Mannitol Salt plate
The Mannitol Salt plate was used for this bacteria
The blood agar was used for this bacteria
In the earlier experiments NOT the unknown
Staphylococci
Streptococci
Mannitol Salt Plate
Used to ID this type of Bacteria
Yellow = this bacteria
Pink = this bacteria
Staphylococcus
Staphylococcus aureus (Breakdown)
Staphylococcus epidermidis (No Breakdown)
What does DSLB and SSLB mean and which 2 species, know as what, was it looking for?
DSLB is 10ml “test water sample”
SSLB is 1 & .1 ml “test water sample
Intestinal bacteria “ E. coli & Enterobacter aerogenes” Coliforms
What is the name of the mechanism in which the CO² was collected in while looking for Coliforms
Durham Tube
The Presumptive test for fecal contamination has 3 indicators for a positive test, name them
Color change from Pink to Yellow
Cloudy growth
Gas bubble in Durham tube (due to Break down of Lactose)
10ml pipette is this color
1ml pipette is this color
Green
Blue
What were the two types of agars we inoculated in the Bacterial Water Exam
What are the positive results for coliforms?
Levine EMB agar: Coliforms produce Large Blue-Black colonies with a green metalic sheen for E coli
Endo agar: Coliform colonies produce Pink to Rose-Red colonies.
What is the gram status and differential mediums used for coliforms?
Gram-negative
Lactose fermentation Presumptive
Levine EMB & Endo agar Confirmed
The Presumptive test for Coliforms: is also used to determine this ______ which is the amount of coliforms present per 100ml water
MPN
Initial dilution of lettuce given to class
1:10
How many mls were transferred from Inital sample to A in lettuce dilution
What was As dilution
How many mls were transferred from A to B
What was its total dilution
. 1ml
1:1000
.1ml
100,000
4 plates were used in the lettuce sample to grow bacteria
What is the dilution if .1 ml is platted from 1:1,000 dilution
10,000
How much does 1ml of water weigh
1 gram
Why are EMB and endo agar used as a confirmation test
They select for Gram-negative and don’t allow Gram-positive to grow
Citrobacter, Enterobacter, Klebsiella, Escherichia are all this type of microbe
Coliforms
Type of plate / plate count used in bacterial count of a food product
Standard methods agar
Heterotrophic plate count
The medium hetrotrophic gives what nutrient to support the growth of bacteria
Organic carbon
EMB agar is selective for gram-negative bacteria.
How does it do this?
How does it differentiate?
The dye methylene blue inhibits the growth of gram positive Selective
Eosin and methylene blue are pH indicator dyes when lactose gets broken down it produces acid Differential
What does EMB stand for in the agar
Eosin methylene blue agar
The selectivity of _____ is due to the sodium sulfite/basic fuchsin combination which results in the suppression of gram-positive microorganisms.
Endo agar
Which metabolic process makes EMB and endo agar differential
Lactose fermentation
The differential ingredient in MSA is…
The selective ingredient is…
The acidity of the media will cause the pH indicator, ______, to turn yellow.
The sugar Mannitol
7.5 % NaCl
Phenol Red
In the lettuce experiment with 4 plates
If .1 ml from B (1: 100,000) is plated what will the concentration be
1,000,000
In the unknown Gram Positive
Cocci get put on this type of plate
Possible outcomes
Rods on this type of plate
MSA: Cocci
Pink Staphylococcus epidermidis(pink)
Yellow Staphylococcus aureus (yellow)
Blood agar: Rods
Beta hemolysis: Bacillus cereus
Gama hemolysis: Bacillus megaterium
Unknown Gram positive Rods got plated on what?
What were the 2 possible outcomes and species.
Blood agar
Beta hemolysis: Bacillus cereus
Gama hemolysis: Bacillus megaterium
Unknown experiment
Cocci Gram-positive got this type of plate
2 possible outcomes
MSA plate Mannitol Salt plate
Pink: Staphylococcus epidermidis
Yellow: Staphylococcus aureus
If 2 plates were done in the Unknown
Which type of staining process was done.
Which stain was used
Simple Stain
Air dry
Heat fix
Methylene blue 1 minuto
S aureus, S epidermidis, B megaterium, B cereus
All have this gram staining property
Gram positive
Alcaligenes faecalis, Escherichia coli, Enterobacter aerogenes, Proteus vulgaris
All have this gram staining property
Gram negative
Thioglycolate is used to determine this in the Unknown Gram negative
Oxygen requirements
In the gram negative Thycogyclate which was the:
Obligate aerobe
Facultative anaerobe
Alcaligenes faecalis ( Obligate Aerobic)
Escherichia coli, Enterobacter aerogenes, Proteus vulgaris
(Facultative anaerobe)
Gram negative Unknown
Citrate agar
Which color indicates no citrate utilization
Which indicates use of citrate
Inoculation instrument
Green = (-) or no use of citrate
Blue/Black = (+) break down of citrate
Loop
Which gram negative species use citrate turning the medium Blue/Black
Which don’t use citrate leaving the agar a Green
Enterobacter aerogenes (Blue/ Black) Use citrate
E. coli, Proteus vulgaris, Alcaligenes faecalis (Green) Don’t use citrate
In the gram negative Unknown
Urease Production is measured in the Urea Slant Agar
Which type of inoculation instrument was used.
What is a Negative/ Positive indicator of Urease Production
Loop
Orange / Pink: Negative
Flaming Pink: Positive
On the Gram negative Unknown
Thioglycolate & Motility Media
Both used this instrument to inoculation
Straight needle
Gram negative Unknown
Urease Production
These bacteria produced Urease with a Flamming Pink Result
These bacteria did not produce Urease with a light pink / orange Result
Proteus Vulgaris Produced Urease Flamming Pink
Alcaligenes faecalis, E coli, Enterobacter aerogenes. No Urease Production light orange
How were the caps adjusted in the Gram-negative unknown
Loose cap
Motile organisms are able to move about the semi-solid medium resulting in a ______ growth throughout the medium.
Non-motile organisms will remain isolated at the inoculation point and will appear as pink or red growth along the stab line.
Which bacteria were motile
pink or red diffuse
All
Thioglycolate is an enriched non-selective broth
T or F
T
Motility test media is which type of media
Differential
This type of (Streaking) is done on the MSA plate:
Blood agar:
MSA: Zig zag
Blood agar: Quadrant Isolation Streak
This is the type of plate used in the Handwashing lab
is a general purpose plating medium used for the isolation, cultivation, and maintenance of a variety of fastidious and non- fastidious microorganisms.
Tryptic Soy Agar (TSA)
Normal flora from handwashing on Tryptic Soy Agar (TSA) Plate had this appearance
Possible pathogens this appearance
Small white dots (Normal flora)
Larger Red (Possible Pathogen)
Type of (Streaking) used on Levine EMB & endo agar
Quadrant streak
How were the counts in the Bacterial food count done
CFU
What is the definitive test for S. aureus
Colagulase
Which gram positive bacteria are positive on a TSA (blood agar plate)
Both
Staphylococcus Aureus ( Beta hemolysis) (Giant colonies)& Staphylococcus epidermidis (Gamma hemolysis)(small white colonies)
Bacillus megaterium ( Gamma hemolysis) & Bacillus cereus (Beta hemolysis)
Which gram positive bacteria are positive on MSA plate.
Which are negative
Positive: Staphylococcus aureus (Yellow-breakdown)
Staphylococcus epidermidis (Pink-no breakdown but growth)
Negative
Bacillus megaterium & Bacillus cereus
The 7.5 salt kills them
_____ broth is the medium we used as a presumptive test for coliform bacteria / water test
DSLB / SSLB
Double/ Single Strength Lactose Broth
Which unknown organisms will grow on PEA (phenyethyl alcohol agar).
Will Grow: Staphylococcus aureus, Staphylococcus epidermidis, Bacillus megaterium, Bacillus cereus
Will not grow: Alcaligenes faecalis, Enterobacter aerogenes, Escherichia coli, Proteus vulgaris
Which unknown will grow in EMB agar (Eosin Methylene Blue)
Gram-negative will Grow: Alcaligenes faecalis, Escherichia coli, Enterobacter aerogenes, Proteus vulgaris
Gram-positive will not grow: Staphylococcus aureus, Staphylococcus epidermidis, Bacillus megaterium, Bacillus cereus
Which medium grew gram-positive
Cocci
Bacillus
Cocci: MSA (Mannitol Salt plate)
Bacillus: Blood Agar
