Enterobacteriaceae Flashcards
What is the motility reaction for Shigella species? Klebsiella pneumonia?
Shigella - 100% neg
Kleb pneumo - 100% neg
What are the phenylalanine deaminase reactions for Proteus species? Providencia species on an LIA?
Phenylalanine deaminase
Proteus
Providencia
Proteus: +
Providencia: +
What is the principle behind serological typing of Salmonella and Shigella species?
The somatic O antigens and flagellar H antigens for Salmonella. Shigella O antigens.
List the Enterobacteriaceae by tribe and include the genus for each:
a) b) c) d) e) f) g)
a) Escherichiaea - Escherichia, Shigella
b) Edwardsielleae - Edwardsiella
c) Samonelleae - Salmonella
d) Citrobacteriaceae - Citrobacter
e) Klebsielleae - Klebsiella, Enterobacter, Hafnia, Serratia
f) Proteae - Proteus, Morganella, Providencia
g) Yersinieae - Yersinia
What are the IMVIC reactions for the following organisms?
E. coli
Indole +
M.R +
V.P -
Citrate -
What are the IMVIC reactions for the following organisms?
Klebsiella pneumoniae
Indole -
M.R -
V.P +
Citrate +
What are the IMVIC reactions for the following organisms?
Klebsiella oxytoca
Indole +
M.R -
V.P +
Citrate +
What are the IMVIC reactions for the following organisms?
Enterobacter aerogenes
Indole -
M.R -
V.P +
Citrate +
What are the IMVIC reactions for the following organisms?
Enterobacter intermedius
Indole -
M.R +
V.P +
Citrate +
Name four characteristics shared by members of the Enterobacteriaceae:
Gram neg rods
Oxidase neg
Nitrates to nitrites
Ferment glucose
Briefly explain the K, O, and H antigens of the Enterobacteriaceae:
K - capsular antigen
O - somatic antigen
H - flagellar antigen
What are the principles of the following biochemical tests?
TSI
alKane(red)/Acid(yellow) - utilized glucose only
alKane/Kalkane - non fermentor
Acid/Acid - utilized glucose and/or Lactose and/or Sucrose
No gas production = nonaerogenic
Gas production (black) = aerogenic, H₂S prod.
What are the principles of the following biochemical tests?
LIA
K(Purple)/A(yellow) - utilized glucose only
K/K - decarboxylated lysine
R(Red)/Y - phenylalanine deaminase
What are the principles of the following biochemical tests?
Indole
if org has enzyme tryptophanase it will dominate tryptophan and make the product indole
Red on top
What are the principles of the following biochemical tests?
Methyl Red
glucose is metabolized by mixed acid fermentation and produces an acidic end product, which decreases the pH and changes color
red color change
What are the principles of the following biochemical tests?
Voges-Porskauer
acid formed are metabolized to 2,3-butanediol through acetone, alpha naphthol and 40% KOH are added, resulting in a red complex
A cherry red color indicates a positive result, while a yellow-brown color indicates a negative result.
What are the principles of the following biochemical tests?
Citrate
uses citrate as sole source of carbon
Blue is pos, green is neg
What are the principles of the following biochemical tests?
Urea
if org can hydrolyze urea to ammonia
All pink = rapidly pos (proteus)
yellow = neg
What are the principles of the following biochemical tests?
Amino Acid Degradation
Lysine:
Arginine:
Ornithine:
Lys→cadaverine yellow if acidic, purple if alk
Arg→putrescine yellow if acidic, purple if alk
Own→putrescine yellow if acidic, purple if alk
What are the principles of the following biochemical tests?
ONPG
If org has B-galactosidase it acts on ONPG to produce galactose and orthonitrophenol
Yellow is pos
What are the principles of the following biochemical tests?
PYR
The org can hydrolyze the substrate PYR
a. L-pyrolidonyl-B naphthylamide
b. L-pyroglutamic acid-B naphthylamide
Pink is positive
What are the principles of the following biochemical tests?
Hippurate
if org has enzyme hippicurase will hydrolyzes sodium hippurate
Deep blue is pos
What are the principles of the following biochemical tests?
Hydrogen Sulfide
organism’s ability to produce H₂S
black is positive
What are the principles of the following biochemical tests?
Tryptophan deaminase (TDA)
produces indole pyretic acid which reacts with ferric ammonium citrate in the medium after addition of ferric chloride to produce a brown color
What are the principles of the following biochemical tests?
Nitrate
Nitrate to Nitrite
positive is red,
What are the principles of the following biochemical tests?
Esculin
if org. hydrolyzes esculin, the product will react with ferric salt to form a black precipitate
black is pos
Why are suspected Salmonella species isolates boiled for 20 minutes if they do not react with O typing sera?
The Vi antigen may block the O antigen and may give a false neg. If the Vi antigen is heated it will be removed and allow access to the O antigen
What is Sorbitol MacConkey agar (SMAC) used to isolate? What disease does this organism cause: What color does it appear on the SMAC plate?
E. coli:
E. coli O157:H7 which causes hemorrhagic diarrhea and hemolytic uremic syndrome it appears as a clear or colorless colony on SMAC plates
Which two genera of Enterobacteriaceae are 100% non-motile?
Shigella and Klebsiella
Which species of Proteus are indole positive?
Proteus vulgaris is indole pos
From what three sources may Salmonella typhi be isolated during the course of typhoid fever?
Blood, Gall bladder, and GI tract
Controlling diseases caused by Salmonella species is complicated by a carrier state. Explain:
Carriers shed organisms continuously or intermittently and feces may contaminate for or water sources
In a simple outbreak of Salmonella gastroenteritis, is it usually necessary to treat the patient with antibiotics? Explain:
If treated by antibiotics, patient may have a higher risk for developing the carrier state.
If treatment is necessary, trimethiprim-sulfamethoxazole is the drug of choice.
What is the purpose of MacConkey & Eosin Methylene Blue agar?
Selective: isolate GNR, inhibit gram pos organisms
Differential: Lactose pos and Lactose neg
E. coli has a very unique reaction on EMB agar. Describe the reaction:
E. coli forms blue-black colonies with a metallic-greenish sheen
What is the purpose of GN broth?
Selective enrichment media that inhibits gram pos bacteria and has high % of mannitol, which temporary favors mannitol-fermenting gram neg rods
Why is zinc dust used in the nitrate test?
If there is a negative color reaction, Zinc dust can be added to the nitrate test to show a color reaction if nitrate is still present, which shows a true negative: if negative color reaction, the nitrate has been reduced to nitrite and then further reduced to gaseous products or a true positive reaction
- What color are non-lactose fermentors on the following media?
Non-lactose fermentors
EMB: translucent, amber color MAC: colorless HE: green/blue green, black H₂S XLD: red/colorless, black H₂S Te7: red
- What color are the lactose fermentors on the following media?
Lactose fermentors
EMB: Pink MAC: Pink/red HE: Orange/salmon-pink XLD: Yellow Te7: Green/blue
Define the term coliforms. Give examples of coliform organisms:
- Organisms commonly seen in GI tract (neg rods) as normal flora
- E.coli, Klebsiella, Enterobacter, Proteus, Pseudomonas
Which genus of Enterobacteriaceae can be easily separated with a strongly positive urea reaction?
Proteae tribe is strong urea pos
Discuss the inoculum size and methodology of Microscan and Vitek systems
Inoculum size is small in Vitek system and is an enclosed walk-away system. Microscan needs more liquid for the inoculum.
Microscan system is a fluorescent color change system, in fl. system, if the microbe begins to use the substance in the well, it breaks a quenching bond for fl. and the well will fluoresce.
Klebsiella pneumoniae
Reactions: TSI MIO CIT LIA Urea
TSI: K/A g MIO: - - - CIT: + LIA: K/K Urea: +
Klebsiella oxytoca
Reactions: TSI MIO CIT LIA Urea
TSI: K/A g MIO: - + - CIT: + LIA: K/K Urea: +
Enterobacter aerogenes
Reactions: TSI MIO CIT LIA Urea
TSI: A/A g MIO: + - + CIT: + LIA: K/K Urea: -
E. coli
Reactions: TSI MIO CIT LIA Urea
TSI: K or A/A g MIO: + + + CIT: - LIA: K/K or A Urea: -
Salmonella
Reactions: TSI MIO CIT LIA Urea
TSI: K/A H₂S MIO: + - + CIT: - LIA: K/K H₂S Urea: -
Citrobacter Freundin
Reactions: TSI MIO CIT LIA Urea
TSI: K/A H₂S MIO: + - - CIT: + LIA: K/A H₂S Urea: +
Proteus vulgaris
Reactions: TSI MIO CIT LIA Urea
TSI: A/A g H₂S MIO: + + - CIT: - LIA: R/A Urea: +
Proteus mirabilis
Reactions: TSI MIO CIT LIA Urea
TSI: K/A g H₂S MIO: + - + CIT: + LIA: R/A Urea: +
Shigella
Reactions: TSI MIO CIT LIA Urea
TSI: K/A MIO: - - - CIT: - LIA: K/A Urea: -
What are the chemicals used in the indole and oxidase test?
Oxidase: C tetra methyl-p-phenylene-diamine-dihydrochloride
Indole: C paradimethylaminobenzaldehyde
Discuss the colony morphology of Klebsiella pneumoniae, E. coli, and Proteus:
Kleb. pneumoniae
Proteus
E. coli
Kleb. pneumoniae: Pink mucoid colonies
Proteus: Swarm on non-selective media
E. coli: Usually dryer pink with surrounding pink precipitated bile salt
What temperature and atmosphere does Yersinia like to grow at?
Grows best at 25-30, ambient atmosphere but will also grow at 37
Mobility, Indole, Ornithine test results
Mobility is positive when turbidity or cloudy growth extends from the line of inoculation.
Indole is positive a pink to red color band is formed at the top of the medium
Ornithine is positive when a dark, turbid purple color in the medium
Colony morphology of Klebsiella and Proteus
Klebsiella - Mucoid
Proteus - Swarming
