Biochemical ID of Gram (-) Bacteria Flashcards
What family is also referred to as “enterics”
Family Enterobacteriaceae
What family is gram-negative bacilli and coccobacilli (rods), non- spore forming, facultative anaerobic composition??
Family Enterobacteriaceae
Family Enterobacteriaceae do not produce _____ except Plesiomonas
cytochrome C oxidase
Family Enterobacteriaceae are motile at body temperatures except what bacteria?
Klebsiella, Shigella and Yersinia
In the specimen collection of the laboratory diagnosis, fecal specimens or stool samples are collected, usually
within first ____ days of illness and ____ the
administration of antibiotic.
four (4); before
In the specimen collection of the laboratory diagnosis, Specimen should be processed within what time
of collection?; if not, place it to appropriate transport
media and kept in what temperature?
1-2 hours; 4 ̊C
In the gram stain of the laboratory diagnosis, Direct smear examination of stool samples is not particularly
helpful in identifying enteric pathogens but may reveal the presence of _____
inflammatory cells
Cultures grow at an optimal temperature of ______
35°C to 37°C
Cultures grow at an low temperatures of ______°C, example of a bacteria is _______
1-5;Serratia and Yersinia
Cultures grow at an low temperatures of ______°C, example of a bacteria is _______
45-50°C; E. coli
To ensure isolation of both opportunistic and
fastidious pathogens, laboratories must provide
appropriate transport media, such as ________
Cary-Blair, Amies, or Stuart media
All Enterobacteriaceae produce similar growth on ___ agars.
blood and chocolate
What bacteria may be mucoid because of their polysaccharide capsule
Klebsiella or Enterobacter
What bacteria “swarm” on blood and chocolate agars.
P. mirabilis, P. penneri, and P. vulgaris
Broth cultures of Y. pestis exhibit what characteristic?
“stalactite pattern”
What bacteria produces bull’s-eye colonies?
Y. enterocolitica
Agar that is best used to characterize gram negative rods
MacConkey AGAR
What agar is selective for gram-negative enteric bacilli
MacConkey AGAR
Lactose fermenter have what color of colonies?
dark pink colonies
Time of incubation of a Rapid Lactose Fermenter
18 to 24 hours
Time of incubation of a Late Lactose Fermenter
48 to 72 hours
Identify the bacteria if it is a Rapid or Late Lactose Fermenter: Escherichia
Rapid Lactose Fermenter
Identify the bacteria if it is a Rapid or Late Lactose Fermenter: Enterobacter
Rapid Lactose Fermenter
Identify the bacteria if it is a Rapid or Late Lactose Fermenter: Klebsiella
Rapid Lactose Fermenter
Identify the bacteria if it is a Rapid or Late Lactose Fermenter: Hafnia
Late Lactose Fermenter
Identify the bacteria if it is a Rapid or Late Lactose Fermenter: Citrobacter
Late Lactose Fermenter
Identify the bacteria if it is a Rapid or Late Lactose Fermenter: Serratia
Late Lactose Fermenter
Identify the bacteria if it is a Rapid or Late Lactose Fermenter: Salmonella arizonae
Late Lactose Fermenter
Identify the bacteria if it is a Rapid or Late Lactose Fermenter: Shigella sonnei
Late Lactose Fermenter
Identify the bacteria if it is a Rapid or Late Lactose Fermenter: Yersinia enterocolitica
Late Lactose Fermenter
Non-lactose fermenter have what color of colonies?
clear
In the biochemical tests on carbohydrate utilization, what bacterium serve as transport enzyme to facilitate the lactose to enter the plasma membrane of the bacteria?
B-galactoside permease or lactose permease
In the biochemical tests on carbohydrate utilization, what is the enzyme that hydrolyzes lactose
into glucose and galactose
B-galactosidase
What fermenter possess both B-galactoside permease and B- galactosidase
LFs
What fermenter do not possess either enzyme
NLFS
What fermenter lack ẞ-galactoside permease but possess ẞ- galactosidase
LLFS
OF Basal Medium produces what color on pH indicator?
brom thymol blue
OF Basal Medium produces what color on uninoculated medium?
green
OF Basal Medium produces what color on alkaline environment?
blue
These reaction are produced by what element?
“Acid produced on both tubes”
oxidizer and fermenter
These reaction are produced by what element?
“Acid only in closed tube”
fermenter and possible obligate anaerobe
These reaction are produced by what element?
“Acid in open tube:”
Oxidizer
What test is used to determine glucose and lactose or sucrose utilization and H2S production, gas production
TRIPLE SUGAR IRON (TSI)
What is the composition of TSI?
10 parts lactose, 10 parts sucrose, 1 part glucose and
peptone
What is the pH indicator of TSI?
Phenol Red - Yellow
What is the ideal pH for the TSI to be called acidic?
pH 6.8
What is the H2S indicator of TSI?
Ferrous sulfate and Sodium thiosulfate
Reactions should be read within an ______ (time) incubation period; otherwise, erroneous results are
possible.
18- to 24-hour
What is the fermenters present on A/A reaction on TSI agar
Lactose fermenter
Sucrose fermenter
Glucose fermenter
What is the fermenters present on K/A reaction on TSI agar?
Glucose fermenter
What is the fermenters present on K/K reaction on TSI agar?
No fermentation - not a member of
Enterobacteriaceae
What are the H2S-producing bacteria in Triple Sugar Iron?
Salmonella
Proteus
Arizona
Citrobacter
Edwardsiella
What test determine the ability of organism to produce B- galactosidase that hydrolyzes ONPG, a colorless compound, into galactose and o-nitrophenol, a
yellow compound (lactose fermenter)
ORTHO-NITROPHENYL-B-D-GALACTOPYRANOSIDE TEST (ONPG TEST)
ONPG remains what color if the organism is an
NLF?
colorless
In ONPG test, the suspension is incubated at ____°C, and
positive results can generally be seen within _____ hours
35°C; 6
What test is performed if glucose is metabolized by the Mixed Acid Fermentation Pathway, stable acid end products are produced, which results in a low pH.
METHYL RED TEST
Reagent used in Methyl Red Test
Methyl Red
Positive Result in Methyl Red Test yields what color?
Red color
Negative Result in Methyl Red Test yields what color?
Yellow
What test detects the organism’s ability to convert the
acid products to acetoin and 2,3-butanediol
VOGES-PROSKAUER TEST
After incubation, what material is added first as a
catalyst or color intensifier?
a-naphtol
Next, 40% _______ or ______(solution) is added
potassium hydroxide (KOH) or sodium hydroxide (NaOH)
Negative Result in Voges-Proskauer Test yields what color?
Yellow
Positive Result in Voges-Proskauer Test yields what color?
Red
What agar is used to differentiate gram-negative bacilli based on decarboxylation or deamination of lysine and the formation of hydrogen sulfide (H2S)
LYSINE IRON AGAR
pH indicator of Lysine Iron Agar
Bromcresol purple
Positive result in Lysine Deaminase yields what color?
Burgundy/Red
Negative result in Lysine Deaminase yields what color?
Purple
What element is formed on the Lysine Decarboxylase?
Cadaverine
Negative result in Lysine Decarboxylase yields what color?
Yellow (acidic-glucose is fermented)
Positive result in Lysine Decarboxylase yields what color?
Purple (presence of Cadaverine)
What are the deaminase-producing bacteria in Lysine Iron Agar?
Proteus
Providencia
Morganella
What are the H2S producer bacteria in Lysine Iron Agar?
Salmonella
Arizona
Citrobacter
Edwardsiella
What test determines whether an organism possesses the enzyme that deaminates phenylalanine to
phenylpyruvic acid.
PHENYLALANINE DEAMINASE (PAD) TEST
What is the purpose of Sulfide (H2S) in Sulfide Indole Motility Agar?
black precipitate
What is the purpose of indole in Sulfide Indole Motility Agar?
organisms that possess the enzyme trytophanase are capable of deaminating tryptophan with the formation of the intermediate degradation products of indole, pyruvic acid, and ammonia.
