Studied by 48 PeopleDescribe the Enterobacteriaceae
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Describe the Enterobacteriaceae
gram-negative bacilli, facultative anaerobes
Name three species of the Enterobacteriaceae that are pathogens. Name the disease that each causes
Klebsiella pneumonia- causes pneumonia shigella dysenteriae- causes shigellosis salmonella typhi- causes typhoid fever
how do these pathogens differ from the non-pathogenic forms?
pathogens do not ferment lactose, but the non-pathogens do ferment lactose
Do all E. coli normally cause disease?
No
What are MacConkey and EMB agar selective for?
gram-negative rods
What do MacConkey and EMB agar differentiate?
lactose fermenters from non-lactose fermenters
Phenylalanine is broke down into---when bacteria that produce phenylalanine deaminase are grown in culture
phenylpyruvic acid
in the phenylalanine deaminase test, a reagent called ferric chloride is added after incubation. What does a positive reaction look like (color)?
a green color
Name a genus in Enterobacteriaceae that is phenylalanine deaminase positive.
Morganella and Proteus
urea is hydrolyzed into___ and ___
ammonia and carbon dioxide (CO2 and NH3)
Name the exoenzyme studied in the urea hydrolysis exercise
urease
name one genus of bacteria that can hydrolyze urea
Proteus mirabillis
after incubation, how can you tell if a urea slant was inoculated with a urease-positive organism or a urease-negative organism?
if positive that slant turns a pink color
Name the indicator that was added to the urea slant before inoculation
phenol red
This indicator is ___ in a solution below pH 8.4 and ___ above pH 8.4
yellow/orange below pH 8.4; pink/red above pH 8.4
What does the acronym SIM stand for?
Sulfur, Indole, Motility
Name the enzyme responsible for sulfide production
cysteine and thiosulfate
After incubation, how can you tell if a SIM tube had been inoculated with an organism positive for sulfide production?
the SIM media turns black
name a genus in Enterobacteriaceae that is positive for sulfide production
salmonella, shiegella, proteus
How is SIM medium used to determine motility of an organism?
when bacteria is stabbed and incubated, growth would be observed throughout the medium and the medium will appear uniformly cloudy if the organism is motile
Name a genus in Enterobacteriaceae that is motile
enterobacter
in the presence of tryptophanase, tryptophan breaks down into ____ plus ammonia
indole
What does Kovac's reagent indicate?
to detect the presence of indole
after incubation, how can you tell if a SIM tube had been inoculated with an indole-positive organism or an indole-negative organism?
if there is a red color then indole is positve