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Micro Lab

Quiz 3

One can expect for all staph microbes to grow on what type of plate? MSA (Mannitol Salt Agar) (
T/F. Only gram negative microbes grow on MacConkey Agar True
T/F. MSA, EMB, and MAC are selective and differential plates. True
Staphylococcus _________ is the most pathogenic of all staphs and most virulent of disease causing bacteria. aureus
Staphylococcus aureus can cause infection in many areas of the body such as skin, deep tissue, and fluids. There are a wide range of harmful enzymes and toxins that can cause what three major things? Kill WBCs, trigger a fibrin clot, cause shock (toxic shock syndrome).
Staphylococcus aureus can produce __________ in food that can make you sick hours after eating. Enterotoxins
The antibiotic resistant strain of Staph aureus is known as what? MRSA (Methicillin Resistant Staph aureus)
MSA plates are selective in nature because of what? It contains a high salt concentration (7.5%), which inhibits many organisms to grow, but allows salt-tolerant (halophilic) organisms such as staph aureus to grow.
MSA plates are differential in nature because of what? It contains sugar mannitol and pH indicator phenol red. Only disease causing staph will ferment in this mannitol changing the mannitol color. Staph epidermidis will grow but it will not change the color.
What can one expect to see when a pathogenic staph organism ferments (breaks down) on a MSA plate? Mannitol acid is released as a by-product and this acid changes the pH indicator from red to yellow. The colonies and the media will turn yellow. (i.e. Staphylococcus aureus)
What can one expect to see when a non-pathogenic staph organism is on a MSA plate? They will grow but they will not ferment mannitol. Therefore growth with no color. (i.e. Staphylococcus epidermidis)
_________ and _______ red allows for differentiation between pathogenic and non-pathogenic staphs. Mannitol / Phenol.
Which of the following would be positive growth non mannitol fermenters or negative growth: micrococcus luteus, Escherichia coli, and Pseudomonas aeruginosa. Micrococcus luteus = positive growth non mannitol fermenters and E. coli and Pseudomonas aeruginosa = negative growth.
What type of plate is used to test a wide variety of microbial diseases that are transmitted by ingesting water bacteria, viruses, and parasites? Fecal flora is a common source for this plate. EMB (Eosin Methylene Blue) Agar (Dark Purple Plate)
EMB plates are selective in nature because of what? The two dyes present (eosin and methylene blue) are selective and inhibit gram positive growth, but allow for gram negative growth.
EMB plates are differential in nature because of what? The sugar lactose can differentiate between non-lactose, lactose fermenters, and heavy lactose fermenters.
Heavy lactose fermenters on an EMB plate will be distinguished by a _________ __________ sheen. Metallic green / this can distinguish E. coli from other gram negatives. (Note: heavy lactose fermenters can look dark purple with the green sheen as well).
On an EMB plate, non-lactose fermenters are what color? What about lactose fermenters? Light pink or colorless / Pink with purple centers
________________ agar is a light purple plate is allows for gram negatives to grow. MacConkey
MAC plates are selective in nature because of what? Bile salts and the dye crystal violet inhibit gram positives and allow gram negatives to grow.
MAC plates are differential in nature because of what? Sugar lactose and pH indicator neutral red allows for differentiation between lactose and non-lactose fermenters. As acid is released into the media it can turn from light pink to red or dark pink to purple.
On a MAC plate, lactose fermenters turn what color? Dark pink or dark purple
On a MAC plate, non-lactose fermenters turn what color Colorless to very light pink
What does CFU stand for? Colony forming units
EMB and MAC plates differentiate between _____________ lactose and non-lactose fermenters. Enteric
MSA plates have a salt concentration of what? 7.5%
MSA plates inhibit most bacterial growth except for ___________________. Staphylococci
Staph that are able to ferment the mannitol in a MSA plate and produce acid (detected by pH indicator), a ____________ zone surrounds the growth. If there is not fermentation the color is _______________. Yellow / colorless
What feature of the MAC plate inhibit gram positive growth? Crystal violet
What features of the MAC plate differentiate enteric gram negatives of their ability to ferment lactose? pH and bile salts
Lactose and dyes _________ and _____________ blue differentiate between enteric lactose fermenters and non-fermenters. Eosin / Methylene
______________ are a large, diverse family of organic molecules that function in cells as structural and energy molecules. Carbohydrates
Cellular _____________ and _______________ are the breakdown and rearrangement of simple sugars into ATP. Respiration / fermentation
______________ is a catabolic pathway whose end products include pyruvate and ATP Glycolysis
______________ is the set of metabolic pathways that BREAK DOWN molecules into SMALLER UNITS that are either oxidized to release energy, or used in other anabolic reactions. Catabolism
The synthesis of complex molecules in living organisms from simpler ones together with the storage of energy; AKA constructive metabolism, is ultimately known as _______________. Anabolism
What type of medium is used to determine an organism's ability to ferment a specific sugar? Phenol red broth
Phenol red indicators consists of a specific _________, salts and ___________, and a small inverted tube (___________ tube) to capture gas produced. Sugar / peptones / Durham tube
When phenol red turns yellow this indicates the organism did what and what kind of reaction did it have? The organisms broken down sugar, fermented the carbohydrate, and produced acid. This is a Positive Reaction.
When phenol red has no color change what does this indicate and what reaction is this? It indicates that the organism is NOT capable of fermenting the carbohydrate substrate and this is a Negative Reaction.
If an organism produces gas in phenol red, where will this be evident? Visible bubble(s) in the Durham tube (inverted tube)
Identification of gram negative enteric bacteria is important in controlling and treating ____________ infections. Intestinal
The group of bacteria found in the intestinal tract belong to the group __________________________________. Enterobacteriaceae
Enterobacteriaceae are short _____-_________ forming bacilli. Non-spore (Note: C-dif is gram positive and forms spores, and would not belong to this group).
________-____________ _________ agar test is designed to differentiate among the species in the Enterobacteriaceae group. Triple-Sugar Iron (TSI)
The group of Enterobacteriaceae are gram negative bacilli capable of fermenting ______________ with the production of _________. Glucose / Acid
Using TSI helps distinguish the Enterobacteriaceae from other gram negative intestinal ___________. Bacilli
The TSI agar test relies on the basis of differentiation in _______________ fermentation patterns and ___________ sulfide production. Carbohydrate / Hydrogen
TSI slants contain lactose and sucrose in ____% concentration and glucose in _____% concentration. 1% / .01%
The phenol red indicator in TSI slants will turn from an orange-red media to _________ in the presence of acids from carbohydrate fermentation . Yellow
TSI slants contain sodium _____________, a substrate for hydrogen sulfide (H2S) production and ferrous ___________ for detection. Thiosulfate / Sulfate (Note: ferrous sulfate is necessary because H2S is not visible alone and this addition allows you to see it as black).
In TSI slants, organisms that are capable of producing ________ will show a blackening in the butt of insoluble ferrous sulfide. Gas
TSI slants are inoculated by the _______-_______ method. Insertion of sterile straight needle from the base into the butt of the slant and as needle is withdrawn, the slanted surface is streaked. Stab-streak
In the TSI slant, if there is an alkaline slant (red) and acid butt (yellow) with or without gas production (breaks in agar) what does this indicate? Only glucose fermentation occurred. It prefers glucose 1st, & which is a small amount, & small amount of acid produced on slant is oxidized rapidly (aerobic). In the butt, the acid reaction is maintained b/c reduced O2 tension & slower organism growth
In the TSI slant, if there is an acid slant (yellow) and acid butt (yellow) with or without gas production, what does this indicate? Glucose along with lactose and/or sucrose fermentation has occurred. Both present in high concentrations, serve as substrates that encourage continued fermentative activities.
In the TSI slant, if there is an alkaline slant (red) and alkaline butt (red) or no change, what does this indicate? No carbohydrate fermentation occurred. Instead, peptones are catabolized under anaerobic and/or aerobic conditions, resulting in an alkaline pH due to the production of ammonia.
What TSI response would be expected in a TSI slant that has an acid slant / acid butt / no H2S? ** EEK ** E. coli / Klebsiella (occur in immunocompromised peeps)/ Enterobacter
What TSI response would be expected in a TSI slant that has an acid slant / acid butt / H2S produced? ** CAP ** Citrobacter, (urinary pathogen) Arizona (version of Salmonella), and some Proteus SSP (causes chronic UTI, pneumonia, bad shit)
What TSI response would be expected in a TSI slant that has an alkaline slant / acid butt / no H2S? ** SP** Shigella (the shits), and some proteus SSP (cause chronic UTIs pneumonia and lots of other real bad shit).
What TSI response would be expected in a TSI slant that has an alkaline slant / acid butt / H2S produced? ** SAC** Salmonella / Arizona / Citrobacter (all of which are bad shit)
What TSI response would be expected in a TSI slant that has an alkaline slant / alkaline butt or no change? **APA** Alcaligenes (pneumonia, septicemia, peritonitis) / Pseudomonas (very common and doesn't usually cause symptoms) / Acinotobacter (bacterimia, pneumonia, UTI and meningitis).
What does IMViC stand for? Indole / Methyl Red / Voges Proskauer / Citrate
In the IMViC test, _____ separate test are used to detect and identify enteric gram-negative bacilli. 4
What does SIM stand for? Sulfur / Indole / Motility
SIM agar is used for indole test which test the ability of an organism to degrade the amino acid ______________ by the enzyme tryptophanase. If the enzyme is broken down indole is released as a by-product. Tryptophan
After inoculation and incubation of SIM agar, ___________ reagent is added to the top of the agar. During this process indole (if present) is extracted from the layer and forms a complex p-__________________________________. Kovac's / dimethylaminobenzaldehyde
In SIM agar, a positive reaction has a __________ ______ reagent layer, while a Negative reaction has a _________ color. Cherry red / Clear (no red)
How many drops of Kovac's is added to the SIM agar? 10 drops
SIM agar can also detect motility in microorganisms. Motility is seen as growth of _______________ organisms not restricted to the line of ________________. Flagellated / Inoculation
T/F. In the SIM agar, if the growth stays confined to the line of inoculation this indicates that is has flagella. False, it indicated it does NOT have flagella
SIM agar detect microorganisms that produce hydrogen sulfide from _________ salts and _____________ that is added to the SIM tube. Iron / Thiosulfate
In SIM agar, when thiosulfate is reduced, __________ _________ (H2S) gas is produced. The gas reacts with the iron salts to form a __________ iron sulfide precipitate, Hydrogen sulfide / black
In the absence of glucose, sucrose, or lactose, some organisms can utilize _________ as a carbon source of energy. Citrate
Presence of the citrate permeate facilitates the transport of citrate in the ________. Cell (bacterial cell)
Citrate is acted upon by the enzyme __________, and bacteria utilizing citrate form ___________ into the medium, which raises the ______ in media becomes alkaline . Citrase / ammonia
In citrate indicator, ______________ blue indicator changes from green to deep __________ blue, which indicates a ______________ reaction. Bromthymol / Prussian / Blue
The clinical application for phenol red, TSI slants, and IMViC are used to identify possible __________ form the intestinal tract and also identify source of the infection-raw food or fecal contamination. Pathogens
What study finds common pathogens and source to contain or eliminate spreading of infection. Epidemiology
Created by: Sam2121



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