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WorksheetsSTOOL SAMPLE PROCESSING
Total questions: 51
Worksheet time: 29mins
What are the aim of culturing a stool specimen?
To detect pathogenic organisms in the stool.
To diagnose typhoid fever, enteric fever, bacillary dysentery
To learn about the source of infection
To determine the severity of infection
There are 3 types of specimen we can use to culture stool. Choose the INCORRECT one.
Stool
Rectal swab
Duodenal or sigmoid aspirate
Urine
If delay in transportation or processing stool specimen is unavoidable, what transportation media should we use?
Cary-Blair
Amies
Stuart
Viral transport medium
Can we culture only ONE stool specimen from a high degree of suspicion patient?
Yes
No
What is the most appropriate quantity of stool specimen?
5 mg
5 g
10 mg
10 g
If we did not process the stool specimen ASAP, the stool will cools. What will happen?
pH drop and inhibit growth of pathogen
pH increases and inhibit growth of pathogen
Increase unpleasing smell
Pathogen will multiply faster
Can we mix stool with urine or water during sample collection?
Yes
No
If we obtain formed or semi-formed stool, how can we handle the specimen?
Use the spoon and pick a portion of stool, mix with transport media
Centrifuge the stool
Use the spoon and pick all stool, mix with transport media
Incubate the stool
If we obtain liquid stool, how can we handle the specimen?
Add 1 teaspoon of liquid to bottle and mix with transport media
Centrifuge the stool
Add the entire liquid to bottle and mix with transport media
Incubate the stool
We should aware of these factors during stool specimen collection and handling.
Patient information on the container
The cleanliness of outside of container
If there is any leaking
If the stool pH is too low
We should reject stool specimens if they are .. ?
Contaminated with urine or water
Has a residual soap or disinfectant
Specimen submitted with additives/fixative
Grossly leaking
Stool specimens often filled with numerous normal flora, thus we need a very specific screening method to identify the presence of pathogen.
For enteric bacteria, what highly selective media we use alongside with MacConkey to screen the pathogens?
HEA
XLD
SSA
FTM
How can we identify the enteric bacteria presence in stool specimen?
Oxidase negative
Ferment glucose
Ferment lactose
Reduce nitrates to nitrites
What is the aim of stool culture for enteric bacteria?
Detect Salmonella spp. or Shigella spp.
Grow Salmonella spp. or Shigella spp.
Inhibit the growth of Salmonella spp. or Shigella spp.
Find the origin of Salmonella spp. or Shigella spp.
How does Selenite F broth able to detect and culture Salmonella spp. and Shigella spp. ?
Inhibits the growth of Gram + bacteria and many Gram -bacteria except Salmonella spp.
Recover Salmonella spp. and Shigella spp. from the stool
Only inhibits Gram + bacteria
Isolating Salmonella spp. and Shigella spp. from the stool
How does XLD able to detect and culture Salmonella spp. and Shigella spp. ?
Inhibits the growth of Gram + bacteria and many Gram -bacteria except Salmonella spp.
Recover Salmonella spp. and Shigella spp. from the stool
Only inhibits Gram + bacteria
Isolating Salmonella spp. and Shigella spp. from the stool
How does SSA able to detect and culture Salmonella spp. and Shigella spp. ?
Inhibits the growth of Gram + bacteria and many Gram -bacteria except Salmonella spp.
Recover Salmonella spp. and Shigella spp. from the stool
Only inhibits Gram + bacteria
Isolating Salmonella spp. and Shigella spp. from the stool
What are the 4 main ingredients of SSA?
Lactose
Bile salts, Sodium Citrate and Brilliant Green
Sodium thiosulfate and Ferric citrate
Neutral Red
Glucose
Why is Salmonella spp. appears to be black colonies?
Produce Hydrogen Sulfide
Produce Oxygen Sulfide
Lactose fermenter
Non lactose fermenter
Why is Shigella spp. appears to be colorless colonies?
Produce Hydrogen Sulfide
Produce Oxygen Sulfide
Lactose fermenter
Non lactose fermenter
Which of these has microorganism that produce hydrogen sulfide?
Which of these is Shigella spp. on HEA ?
Which spp. can cause acute gastroenteritis?
Salmonella spp
Shigella spp
V. Cholerae
E. Coli
Which spp. can cause enteric fever or thypoid?
Salmonella spp
Shigella spp
V. Cholerae
E. Coli
Which spp. can cause bacillary dysentery?
Salmonella spp
Shigella spp
V. Cholerae
E. Coli
Choose the CORRECT biochemical characteristics of Salmonella spp.
Non lactose fermenter
Produce hydrogen sulfide
Indole negative
Urease positive
Choose the CORRECT biochemical characteristics of Shigella spp.
Non lactose fermenter
Produce hydrogen sulfide
Non motile
Does not hydrolyze urea
When do we report a positive enteric bacteria infection?
Isolated and detect Salmonella or Shigella spp.
Inhibit the growth of Salmonella or Shigella spp.
Gain information about Salmonella or Shigella spp.
How can we report a negative enteric bacteria infection?
2 days after No Enteric Pathogens isolated
A week after No Enteric Pathogens isolated
24 hours after No Enteric Pathogens isolated
A month after No Enteric Pathogens isolated
What can interfere with the result of culturing enteric bacteria (salmonella & shigella) ?
Patient on antibiotic
Improper sample collection
High temperature
Increase pH
V. Cholerae causes .. ?
Cholera
Gastroenteritis
Food poisoning
Septicaemia
What is the aim of stool culture for vibrio cholerae?
Detect V. Cholerae from stool and perform identification test
Isolate V. Cholerae from stool and perform AST
Detect V. Cholerae from stool and perform AST
Isolate V. Cholerae from stool and perform identification test
What are the media used to perform stool culturing for vibrio cholerae?
Alkaline peptone water
XLD
TCBS
Sorbitol MacConkey
Why do we use alkaline peptone water to culture stool specimen for vibrio cholerae?
High pH provides a favorable environment for the vibrio's growth and inhibit unwanted normal flora
Low pH provides a favorable environment for the vibrio's growth and inhibit unwanted normal flora
High pH provides a favorable environment for the vibrio's and normal flora growth
Low pH provides a favorable environment for the vibrio's and normal flora growth
How do we indicate growth in Alkaline Peptone Water when performing stool culture for Vibrio Cholerae?
Turbidity
Color changes
Change of pH
Produce gas
What type of agar is TCBS agar?
Enrichment
Selective
Differential
Indicator
How does TCBS agar able to grow V. Cholerae?
Has 1% sodium chloride and a very high pH
Has 1% sodium chloride and a very low pH
Has 1% calcium chloride and a very high pH
Has 1% calcium chloride and a very low pH
This is TCBS agar. Which of these shows the growth of V. Cholerae?
Why does yellow colonies can be seen on V. Cholerae growth compare to other vibrios?
Lactose fermenter
Non lactose fermenter
Sucrose fermenter
Non sucrose fermenter
Which ingredient in TCBS agar inhibits the growth of gram positive bacteria?
1 % Sodium Chloride
Bile salts
Sucrose
High pH
This is V. Cholerae on blood agar. What type of hemolysis is this?
Alpha
Beta
Gamma
This is V. Cholerae on MacConkey agar. What can we say about the microorganism?
Lactose fermenter
Non lactose fermenter
Sucrose fermenter
Non sucrose fermenter
When can we report a positive V. Cholerae case?
Once isolate V. Cholerae
Once inhibit V. Cholerae
Once found the cause of V. Cholerae
Once learn about V. Cholerae
How does E. Coli O157:H7 differs from other strain of E. Coli?
Express shiga-like toxins
Express toxic antigen
Causes cancer
Causes brain failure
E. Coli O157:H7 is usually transmitted via .. ?
Fecal-Oral
Air
Mosquito
Water
What is the aim of stool culturing for E. Coli O157:H7?
Detect E. coli O157:H7 and perform AST
Detect E. coli O157:H7 and perform identification test
Inhibit E. coli O157:H7 and perform AST
Inhibit E. coli O157:H7 and perform identification test
What agar can we use to process stool culture of E. Coli O157:H7?
SMAC
MacConkey
HEA
TCBS
A microorganism is inoculated on Sorbitol MacConkey (SMAC). There is a growth of non-sorbitol fermenting colonies. What do we do after this?
Perform latex agglutination
Perform AST
Perform biochemical test
Report to physician
If pink colonies found on SMAC agar, what microorganism is that?
E Coli O157:H7
E Coli
V. Cholerae
Shigella spp
Why E. Coli O157:H7 produce pale, colorless colonies on SMAC agar?
Non lactose fermenter
Lactose fermenter
Non Sorbitol fermenter
Sorbitol fermenter
In order to confirm E. Coli O157:H7 during its latex test, we can decide if .. ?
Positive control
Positive H7 antigen
Positive O157 antigen
Negative control
