Enterobacteriaceae, Introduction & Testing Flashcards
What do Methyl Red and Vogues-Proskaur determine?
End products of glucose fermentation
What does the Indole test determine?
If Indole is formed from tryptophan by tryptophanase
What does the urease test determine?
Hydrolysis of urea
What does Simmon’s citrate determine?
If citrate can be used as the sole carbon source
What does the Lysine Iron Agar (LIA) determine?
Lysine decarboxylase activity
What is SMAC?
MacConkey agar with soribitol
What does alpha hemolysis look like?
Green discoloration of the media
What does beta hemolysis look like?
Complete clearing of erythrocytes around colonies
What does Triple Sugar Iron (iron) agar determine?
Glucose and lactose, or sucrose utilization and hydrogen sulfide production
Which GI pathogen is characterized by watery diarrhea which turns to bloody diarrhea but has no leukocytes?
E.coli O157:H7
Media used for detection of salmonella and shigella
XLD, HEK, SS
One or the other
Media used for isolation of Yersinia only, incubates at room temperature
CIN
Media that selectively enhances the growth of salmonella and shigella while suppressing the growth of normal bowel flora, also used for the detection of shiga-like toxin producing strains of E.coli
GN broth/selenite
Media for isolation of Campylobacter - incubates at 42 Celsius
Campy agar
Media for isolation of Vibrio
TCBS
Thiosulfate-citrate-bile salts-sucrose
Media for detection of pathogenic strains of E.coli
MAC Sorbitol
Media for isolation of salmonella
Bismuth sulfite
Immunologic tests available for:
Shiga-toxins, campylobacter, C.diff, H.pylori
GI culture collection
-if not processed quickly, should be collected and transported in:
Cary-Blair, Amie’s or Stuart media
Microscopic examination of stool for:
WBCs - inflammatory diseases
GI culture collection
-preservatives should be used if examination for _________ is intended
Ova and parasites
-avoid preservatives if cultures are ordered
At the very least, stool cultures should set up media for the detection of:
Salmonella, shigella, campylobacter
_______ and _____ media are used to ID bacterial pathogens in stool
Selective and differential
_______ media contain antimicrobial said or chemicals to limit the growth of normal bacterial flora and to enhance the growth of pathogenic bacteria
Selective
Salmonella TSI results
K/A+
E.coli TSI results
A/Ag
Proteus TSI results
K/A+
Klebsiella TSI results
A/Ag
Shigella TSI results
K/A
A pink colony on SMAC indicates what organism?
E.coli other than O157:H7
The Kaufman White Scheme is used to serotype which organism?
Salmonella
Name the organism that can lead to a carrier-state in the host after infection for which removal of the gallbladder is sometimes the only cure
Salmonella
Which of the Enterobacteriaceae is known to be highly drug resistant?
Klebsiella
Which GI pathogen requires only a very small inoculum and it also resists stomach acid?
Shigella
Which E.coli causes traveler’s diarrhea?
ETEC
Which E.coli causes Hemolytic uremic syndrome (HUS)?
EHEC
Which E.coli causes dysentery?
EIEC
CIN
Yersinia
SMAC
E.coli except O157:H7
Swarming colonies
Proteus
Bismuth sulfite
Salmonella
Red pigment
Serratia
Burnt chocolate smell
Proteus
ESBL
Klebsiella
Vi antigen
Salmonella
Mug (+)
E.coli except O157:H7
Widely test (+)
Salmonella
Safety pin appearance on gram stain
Yersinia
How does a positive motility test appear?
Cloudiness around inoculation line
Name a test that detects motility
SIM
Name an organism that would give a positive motility reaction
E.coli
Name an organism that would give a negative motility reaction
Klebsiella
The production of acetylmethylcarbinol from dextrose is the principle of which test?
Vogues-Proskaur
In which test is ammonia formed?
Urease
What is the amino acid from which indole is formed in the indole test?
Tryptophan
What must be added to the indole test before reading?
Kovac’s or Erlich’s reagent
How would the following tests be resulted for klebsiella?
Indole, citrate, VP
Indole: (-)
Citrate: (+)
VP: (+)
If the methyl red test is red, the MLT should report the test as:
Positive
If a SIM media is black, what does this indicate?
Positive - production of hydrogen sulfide
What is Christensen’s media used for?
Citrate
What is the pH indicator in TSI?
Phenol red
Name a urea positive organism:
Proteus mirabilis
After the addition of Kovac’s reagent, there is a pink color at the interface of the reagent and the media. This is the ______ test
Indole
In the TSI, the media is pushed up off the bottom of the tube. What would this indicate?
Gas production
If a TSI is solid yellow, how would you report it? What sugars were utilized?
A/A
Glucose, lactose and or sucrose fermentation
If a citrate is green, it is reported as _____. Name an organism that would give this result
- negative
- E.coli
Name the three sugars in TSI
- glucose
- lactose
- sucrose
If a urea test is pink, how would it be reported?
Positive
Name an organism that would give a pink result on a urea test
Proteus mirabilis
What must be added to a VP test before the test can be interpreted?
Alpha naphthalene and KOH
Positive reaction appearance for VP
Red
Positive reaction appearance for Indole
Red
Positive reaction appearance for LIA
Purple
Which organism has an IMViC reaction
of ++–?
E.coli
How is klebsiella differentiated from Enterobacter biochemically?
Klebsiella is ornithine (-) and motile
Enterobacter is ornithine (+) and nonmotile
Which test produces acetylmethylcarbinol from dextrose?
Voges Proskauer
Which test causes fermentation of glucose?
Methyl red test
Which test produces ammonia?
Urea test
Which test uses Simmons medium?
Citrate test
Which test uses Christensen’s medium?
Urea test
Which test utilizes citrate as a carbon source?
Citrate test
If an Enterobacteriaceae is motile, where on the organism are the flagella found?
All the way around
Peritrichous
A yellow color appears in a nitrite test after the addition of zinc dust. This result is considered to be:
Positive
A red result in LIA indicates
Deanimation of lysine
Which test is KOH associated with?
Voges Proskauer
Which test is Kovac associated with?
Indole
Which test is Alpha naphthal associated with?
Voges Proskauer
Which test is Erlich associated with?
Indole
Utilization of sucrose I’m TSI is demonstrated by the appearance of:
Yellow/yellow slant
A methyl red test result is yellow. This indicates a ________ reaction
Negative
A TSI that should be K/A is read too early. How will it appear?
A/A
Name the reagents that must be added to the Voges-Proskauer test before it can be interpreted
Alpha naphthol and KOH
Which E.coli causes infantile diarrhea?
EPEC
What causes typhoid?
Salmonella
What causes Pseudomembranous colitis?
Clostridium
What causes HUS?
E.coli O157:H7
What causes dysentery?
Shigella
How does shigella appear on MAC and HEK?
- Colorless on MAC
- green/clear on HEK
What is shigella’s TSI?
K/A
Name three organisms that are phenylalanine deanimase
- proteus
- providencia
- morganella
Is salmonella normal flora in stool?
No, it’s always a pathogen
If the MUG test is negative, what possible pathogen is indicated?
EHEC - Enterohemmoragic
E.coli O157:H7
How can shigella and salmonella be differentiated by TSI?
Shigella - K/A
Salmonella - K/A++
Name an organism that produces a dark red pigment
Serratia
What is the name of the chromogen that causes this red pigmentation?
Prodigiosin
The TSI is red over yellow. How would this be reported?
K/A
Enterobacteriaceae gram stain reaction:
Gram negative rods or coccobacilli
Enterobacteriaceae glucose reaction
Fermentation
Enterobacteriaceae oxidase reaction:
Negative
If a colony is pink on MAC, this indicates:
Lactose fermenter
An organism that has a green metallic sheen on EMB would be identified as:
E.coli
Positive citrate
Klebsiella
Positive Indole
E.coli
Proteus
Positive urease
Klebsiella
Proteus
Positive VP
Klebsiella
What causes cholera?
Vibrio
What causes plague?
Yersinia
What causes ulcers?
Heliobacter
