Lab Question Set 2 Flashcards
Enzymes called decarboxylases catalyze the removal of the _________________ from an amino acid.
5-11: Decarboxylase Test
Carboxyl group
Enzymes called deaminases catalyze the removal of the ________________ from an amino acid.
5-11: Decarboxylase Test
Amines
What is meant by the substrate of an enzyme?
5-11: Decarboxylase Test
The substrate of an enzyme is amino acid that has its variable group removed during the reaction resulting in the production of an amine or carboxyl group being released
Decarboxylases catalyze reactions that produce ________________ (pH) products.
5-11: Decarboxylase Test
Alkaline
The pH indicator bromocresol purple is ______________ at pH 6.8 and above and ______________ below pH 5.2.
5-11: Decarboxylase Test
Purple
Yellow
Why is mineral oil added to the decarboxylase broth tubes before incubation?
5-11: Decarboxylase Test
To seal off from oxygen and encourage fermentation
Why does the decarboxylase-positive tube have to turn yellow before it can turn purple?
5-11: Decarboxylase Test
- Accumulation of acidic end products will occur first
- Then low pH organisms will react to acidic enviornment and either produce decarboxylases or not resulting in positive (purple) or negative (yellow) results
Describe a positive result in this experiment and describe a negative result. What kind of pH is present in a + result and is present in a - result?
5-11: Decarboxylase Test
Positive: Purple, Alkaline, decarboxylases resulted in an increase in pH
Negative: Yellow, Acidic, lack of decarboxylases meant pH remained negative
Why is glucose included in the decarboxylase broth?* (Hint: answer is not “as a food source”)
5-11: Decarboxylase Test
- Low glucose concentration promotes fermentation lowering pH and causing proteases to activate (decarboxylase)
This decarboxylation test cannot be performed successfully on organisms that cannot ferment glucose. Explain why this is the case.*
5-11: Decarboxylase Test
- If the organism cannot lower the pH through fermentation the proteases will not be activated and no color change will occur
Cadaverine and putrescine are examples of compounds known as __________________.
5-11: Decarboxylase Test
Diamines
The names, cadaverine and putrescine, suggest that the compounds might be found in _______________, which they are, as a result of the decarboxylation of ________________ (what molecule) by bacteria.
5-11: Decarboxylase Test
- Rotting Flesh
- Lysine -> Cadaverine
- Ornothine -> Putrescine
What is phenylalanine (what type of monomer is it)?
5-12: Phenylalanine Deaminase
- Amino Acid substrate
Phenylalanine is part of an ingredient found in the popular artificial sweeteners known as _________________ or ___________________.
5-12: Phenylalanine Deaminase
Aspartane
Nutrasweet
The enzyme that some bacteria can produce that removes an amino group from phenylalanine is called ___________________________________.
5-12: Phenylalanine Deaminase
Phenylalanine Deaminase
The reagent that is added to bacterial growth on phenylalanine deaminase agar in order to determine if the enzyme has been produced, is __________________________.
5-12: Phenylalanine Deaminase
Ferric Chloride
Describe a positive result in the experiment and a negative result.
5-12: Phenylalanine Deaminase
- Green indicates positive as Phenolpyruvate is present
- Yellow indicates negative as no phenolpyruvate is present
- Note this is not a pH test as the phenyl pyruvate and ammonium cancel eachother’s pH
Phenylalanine is broken down to _____________________ and _____________________.
5-12: Phenylalanine Deaminase
Ammonium
Phenylpyruvic Acid
Why can’t you use a pH indicator to detect phenylalanine deamination?
5-12: Phenylalanine Deaminase
Because the Phenylpyruvic acid (acid) and Ammonium (base) cancel eachother’s pH
A green color results in this experiment if _______________________________ reacts with the reagent ________________________.*
5-12: Phenylalanine Deaminase
Phenylpyruvic Acid
Ferric Chloride
Like all amino acids, phenylalanine is a source of the two elements ______________ and _____________ for the bacteria.
5-12: Phenylalanine Deaminase
Nitrogen
Carbon
Write the chemical formula for an amine group (amino group).
5-12: Phenylalanine Deaminase
NH2
What is the difference between the deamination and the decarboxylation of an amino acid (Hint: think of oxygen requirements)?
5-12: Phenylalanine Deaminase
Decarboxylation occurs in anaerobic conditions
Deamination occurs in aerobic conditions
Urea can be hydrolyzed to carbon dioxide and ___________________ by bacteria that produce the enzyme ______________________________.
5-18: Urease Test
Ammonium
Urease
Urinary tract pathogens from the genus ______________________ can be distinguished from other enteric bacteria by their rapid urease activity.
5-18: Urease Test
Proteus
What other disease is caused by this organism? (Proteus)
5-18: Urease Test
Proteus mirabilis and Proteus vulgaris cause diaper rash
H. Pylori causes stomach ulcers
Urease-positive organisms break down urea to _______________, which ________________ the pH of the medium and changes the color of the pH indicator phenol red from _______________ to _______________.
5-18: Urease Test
Ammonium
Increases
Orange
Pink
Describe a positive urease test and a negative test (include the relative pH).
5-18: Urease Test
Pink: Urease was produced leading to release of ammonium as urea broke down (+), pH >8.4
Orange: (-) pH <8.4
Yellow: Organism was unable to produce urease and did not break down urea (-), pH <8.4
In order for a urease-positive organism to turn the urea broth pink, the organism must ___________________ the pH of the medium enough to overcome the effects of the __________________, potassium phosphate.
5-18: Urease Test
Increase
Buffer
The urease test is an important part of the identification of the organism _________________________ , that causes peptic ulcers.
5-18: Urease Test
H. pylori
How does this organism (H. pylori) survive stomach acid?
5-18: Urease Test
Rapid Urease production leads to ammonium production which can neutralize the stomach acid
A rapid urease test is performed on the ______________________ of patients with peptic ulcer symptoms.
5-18: Urease Test
majority
Why is it important that urease broth contain a buffer that can resist alkalinization of the medium from peptone metabolism?*
5-18: Urease Test
To avoid false positives from reversion of peptone metabolism
Ammonia is used by many bacteria as a source of the element ______________________.
5-18: Urease Test
Nitrogen
Bacteria use nitrogen, in order to make what two classes of macromolecules?*
5-18: Urease Test
Nucleic acids and Polypeptides
TSI is a differential medium that is useful in differentiating _______________________________________.
2-7: Triple Sugar Iron (TSI) agar
Fermentation
Triple Sugar Iron agar contains 3 sugars in its recipe. The monosaccharide ___________ is supplied in a low percentage (0.1%) while the disaccharide sugars ____________ and ____________ are provided in a higher percentage (1%).
2-7: Triple Sugar Iron (TSI) agar
Glucose
Lactose
Sucrose
The results of TSI tubes are recorded according to the pH of the __________ over the pH of the ________(e.g., K/A). The pH indicator in TSI is __________________ which is the color ______________ when it’s acidic and ______________ when it’s alkaline.
2-7: Triple Sugar Iron (TSI) agar
Slant
Butt
Phenol Red
Yellow
Red
Fermenters only capable of fermenting _______________ will run out of sugar within the first few hours during incubation. Explain what these organisms do next and what the results look like in both the slant and butt.
2-7: Triple Sugar Iron (TSI) agar
Glucose
- These organisms will then swap to peptone digestion which will turn the slant red while the anaerobic butt remains yellow
Fermenters capable of fermenting one or both disaccharides (sucrose and/or lactose) will never run out of sugar during the required 24-hour incubation. Explain what TSI slant looks like in this case.
2-7: Triple Sugar Iron (TSI) agar
- Because Fermentation will occur throughout the entire 24H period the slant and butt will both be yellow
Besides sugar, other substrates found in TSI agar include _____________ and ________________________. These substrates are a source of reducible ____________, and digestion of these substrates leads to the formation of H2S.
2-7: Triple Sugar Iron (TSI) agar
Cysteine
Sodium Thiosulfate
Sulfur
H2S is a colorless gas that smells like rotten eggs. It is visually detected when a black color (precipitate) forms by reacting with the iron-containing ingredient ___________________________________.
2-7: Triple Sugar Iron (TSI) agar
Ferrous ammonium sulfate
H2S can be made by certain species of sulfur-reducing bacteria. The formation of H2S requires a reducing environment where excess hydrogen is present, and the pH is _____________.
2-7: Triple Sugar Iron (TSI) agar
Acidic
Explain why a K/K [H2S +] result is not possible.
2-7: Triple Sugar Iron (TSI) agar
Because in order for the agar to be H2S+ it would require an acidic environment which is not possible if the tube is K/K
Enzymes that are released into the bacterial environment and work there are known as ______________________________.
2-7: Triple Sugar Iron (TSI) agar
Exoenzymes
Bacteria that produce protein-digesting (proteolytic) enzymes break down large ___________________ to smaller _____________________ or individual ____________________.
5-16: Casease Test
Proteins
Peptides
Amino Acids
Why do bacteria have to break down proteins in their environment (outside the cell) in order to use the proteins as a food source?
5-16: Casease Test
Because it is too big to be taken across the membrane and therefore needs to be broken down.
Why is milk opaque?* Why does the milk agar turn clear when an organism produces the casease enzyme?*
5-16: Casease Test
Casein is the protein that gives milk its white color but when it is broken down it becomes clear and less opaque
Top line is Casease +
What is a polypeptide? What is the difference between a polypeptide and a peptide? Between a polypeptide and a protein? Between a peptide and an amino acid?
5-16: Casease Test
- A polypeptide is a long chain of amino acids
- A peptide is a shorter chain of amino acids
- A protein can be made of multiple polypeptides
- An amino acid is a monomer.
What is the difference between casein and pancreatic digest of casein?
5-16: Casease Test
- Casein is large bulky protein
- Pancreatic digest of casein has been broken down and is an accessible food source
Why are whole, undigested proteins (as opposed to peptones), not usually included in the microbiological growth media?*
5-16: Casease Test
Because they’re often too large or hard to break down if the bacteria dont have the right exoenzymes. Food sources must be able to be digested and taken into the cell
Most nitrate-reducing bacteria contain the enzyme ________________________ and perform a single-step reduction of nitrate.
5-8 Nitrate Reduction
Nitrate Reductase
What is denitrification?
5-8 Nitrate Reduction
The loss of biologically available nitrogen; occurs by release of nitrogenous gas
Write the chemical formulas for nitrate, nitrite, potassium nitrate, ammonia, ammonium ion, molecular nitrogen, and nitric oxide.
5-8 Nitrate Reduction
Nitrate: NO3
Nitrite: NO2
Potassium Nitrate: KNO3
Ammonia: NH3
Ammonium ion: NH4+
Nitrogen: N2
Nitric Oxide: NO
Why is the conversion of nitrate to nitrite an example of reduction?
5-8 Nitrate Reduction
Because you go from NO3 to NO2 which is a gain in electrons for nitrogen as nitrogen’s oxidation state goes from +5 to +3 (oxidation state going down is reduction)
Why is the conversion of nitrite to the ammonium ion an example of reduction?
5-8 Nitrate Reduction
Because you go from NO2 to NH4+ and the oxidation state goes from +2 to -3 which is reduction
Why do bacteria need nitrogen (which 2 macromolecules require nitrogen)? (2 answers)*
5-8 Nitrate Reduction
Nucleic acids and Peptides
Why are there Durham tubes in the nitrate broth?
5-8 Nitrate Reduction
Because if denitrification occurs, N2 gas will be produced
Explain thoroughly each of the following results in this experiment.
a. After incubation, turbid nitrate broth turns red when test reagents A and B are added.
b. After incubation, turbid nitrate broth does not turn red when reagents A and B are added.
c. A turbid tube that did not turn red when reagents A and B were added turns red when zinc is added.
d. A turbid tube that did not turn red when reagents A and B were added does not turn red when zinc is added.
e. There is gas in the Durham tube after incubation with a non-fermenting organism.
5-8 Nitrate Reduction
A. (+) Nitrate is present and bacteria did reduce nitrate
B. Zinc must be added to determine if zinc can reduce nitrate (-) or if no nitrite is present (+). Either no reduction or full reduction occured
C. (-) Red indicates bacteria did not reduce, the zinc did
D. (+) Bacteria were able to reduce nitrate broth and either underwent ammonification or underwent full nitrification
E. (+) Full denitrification occured resulting in gas in durham tube
Describe the results that would occur in an uninoculated control tube when reagents A and B are added to it?* Why?*
5-8 Nitrate Reduction
The tube would stay transparent as there is no nitrite to react with
What results should an uninoculated control tube give when ONLY zinc is added to it?* Why?*
5-8 Nitrate Reduction
The broth should remain transparent as the zinc is for reducing the broth but is not an indicator
What results should an uninoculated control tube give when reagents A, B, and zinc are added to it?* Why?*
5-8 Nitrate Reduction
The Tube will turn red because the zinc will reduce nitrate and the indicator will show the presence of nitrite
What do reagents A and B test for? What does the zinc test for?
5-8 Nitrate Reduction
- Reagents A and B test for nitrite presence. - - Zinc test if reduction occured and will turn nitrate into nitrite if it has not already occured
Why is the conversion of nitric oxide to molecular nitrogen an example of reduction?
5-8 Nitrate Reduction
Because the electronegativity went from +2 to 0
After incubation, gas in the Durham tube in a tube inoculated with a non-fermenting organism means that _____________________ has occurred. Is this a + or a – test for nitrate reduction? What type of gas has been produced?
5-8 Nitrate Reduction
Denitrification
Positive
Nitrogen
What is the original source of nitrate in the nitrate broth? Write the formula for this compound.
5-8 Nitrate Reduction
KNO3
What are aerobic bacteria? (see textbook)
5-6 Catalase Test
Bacteria that require an oxygenated environment because they use oxygen as their final electron acceptor
What are aerotolerant bacteria? (see textbook)
5-6 Catalase Test
Bacteria that can grow in an oxygenated environment but prefer an anaerobic environment
What are facultative bacteria? (facultative anaerobes) (see textbook)
5-6 Catalase Test
Facultative anaerobes can grow better with oxygen but still grow at a slower rate in an anaerobic environment
Aerobic and aerotolerant bacteria produce enzymes capable of detoxifying 2 very potent cellular toxins, ___________________________ and __________________________.
5-6 Catalase Test
Superoxide dismutase
Catalase
The enzyme _____________________ catalyzes conversion of ______________________, the more lethal of the 2 compounds, to _________________________.
5-6 Catalase Test
Superoxide dismutase
Superoxide radicals
Hydrogen peroxide
The enzyme __________________ converts hydrogen peroxide to _____________ and _________________.
5-6 Catalase Test
Catalase
Water
Oxygen
What happens when hydrogen peroxide is added to a catalase-positive culture? What is the appearance of the catalase-negative culture when hydrogen peroxide is added?
5-6 Catalase Test
- The culture will fizz and bubble
- A catalase negative culture will not bubble when it encounters hydrogen peroxide
This test is most commonly used to differentiate members of the catalase-positive __________________________ from the catalase-negative __________________________.
5-6 Catalase Test
Micrococcaceae
Streptococcaceae
If an organism is catalase-negative, what does that tell you about its oxygen requirements?* Why?*
5-6 Catalase Test
It is anaerobic because it does not have a way to get rid of superoxide radicals
If an organism is catalase-positive, what does that tell you about its oxygen requirements?* Why?*
5-6 Catalase Test
It is aerobic as it has a way to get rid of harmful superoxide radicals
What is the morphology and gram reaction of the organism used in this experiment? Even before you performed the catalase test on this organism, you should suspect that it is catalase positive because:
5-6 Catalase Test
S. Epidermidis (Gram positive coccus) which lives on the skin and is an aerobe.
E. Faecalis (Gram positive coccus) which is found in the colon where there isn’t much oxygen.
Would you expect bacteria that are facultative anaerobes to be catalase-positive or catalase-negative?* Why?*
5-6 Catalase Test
They should be catalase positive because using oxygen as an electron acceptor will lead to superoxide radical productions. This means bacteria must have a way to deal with them
The oxidase test that is useful in the presumptive identification of the gram-negative coccus _________________________. Name 2 diseases caused by species of this genus.
5-7 Oxidase Test
Neisseria
N. meningitidis causes meningitis
N. gonorrhoeae causes gonorrhea
Bacteria that belong to the family Pseudomonadaceae are oxidase __________________; bacteria that belong to the family Enterobacteriaceae are oxidase ________________________.
5-7 Oxidase Test
Positive
Negative
What does a positive oxidase test look like? Include the time frame.
5-7 Oxidase Test
A positive test will result in a purple smear after 20 seconds
What does a negative oxidase test look like? (2 answers)*
5-7 Oxidase Test
No color change within 20sec
Color change (pink)after a minute due to reagent oxidation
If your bacteria turn pink after more than one minute has elapsed since the oxidase reagent was added, why is this happening?
5-7 Oxidase Test
The reagents are unstable and were oxidized independently given enough time
The quantitative sensitivity disk method of antibiotic sensitivity testing is called the _________________
method.
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
Kirby-Bauer
In this method, the diameter of the ___________________________ around the disk is measured to the
nearest _____________________ (unit).
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
Zone of inhibition
Milimeters
The inhibition zone diameter that is produced in this experiment will indicate the ___________________ of a bacterium to each antibiotic.
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
Sensitivity
How do you determine if an organism is susceptible to a particular antibiotic in this test? How do you determine if the organism is resistant?
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
The susceptibility zone is measured and compared to a document that states according to what antibiotic is being used a diameter under X is resistant and over X is susceptible
What will a negative test for antibiotic sensitivity look like? Describe such a result and explain what it means.
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
A negative would be shown as no ZOI or a small ZOI. This means that the antibiotic was unable to stop or kill the bacteria
What will a positive test for antibiotic sensitivity look like? Describe such a result and explain what it means.
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
A large ZOI that is greater than the susceptibility break point
ex. Breakpoint <10mm, actual D = 18mm
Why is it important that the sensitivity disks used in this experiment contain a specific, standardized amount of antibiotic?* How is this test standardized (i.e. what is standardized in this test)?(4)
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
- To ensure all results are reliable and safe for humans
- The agar is 4mm (thinner than usual) to promote lateral diffusion
- pH is kept to 7.2-7.4 to mimic blood pH
- Agar is incubated at 37 degrees C to mimic human body temp
- Agar is incubated for 18 hours to select for younger bacteria
Why is it important that the results of antibiotic sensitivity test guide treatment of bacterial infections?
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
It allows us to understand how different drugs interact with bacteria and what is an effective medication that could be used to adress a bacterial infection appropriately
Penicillin is an antibiotic produced by the mold ________________________ (genus), which is also responsible
for __________________________ (type of food).
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
Penicillium
Cheese
What is “intermediate susceptibility” to an antibiotic?* Under what conditions would it be appropriate to use an antibiotic to which a particular organism was intermediately susceptible?*
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
- When the ZOI is above resistant but below susceptibility
ex. R<5, I=6-8, S>9 - Appropriate if the person is allergic to other antibiotics or can be used with another drug for enhanced effects
True or false: All bacteria found within the clear area around the disks are dead. Why did you answer true or false?
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
False. There are bacteriostatic antibiotics which are not bacteriocidal. Often times with gram negative infections when they are lysed they release lipid-A which is toxic and can cause shock and even death. Therefore a bacteriostatic drug is better to pause development and allow the patient’s body to fight the infection in a safer way
What is a broad-spectrum antibiotic? When would it be better to use a broad-spectrum antibiotic? Why?
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
A broad-spectrum antibiotic is an antibiotic that many bacteria are susceptible both gram positive and gram negative. Broad spectrum antibiotics are generally reserved as a last ditch effort as it also kills natural flora. Otherwise targetted antibiotics are usually more appropriate
What is a narrow spectrum antibiotic? When would it be better to use a narrow spectrum antibiotic? Why?
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
Narrow spectrum antibiotics are antibiotics that are effective at targetting a specific bacteria. This is effective when you know exactly what the bacterial infection is and will not affect your natural flora
What is drug synergy? What does plate look like if two drugs are synergistic?
7-3 Antibiotic Sensitivity Testing (Kirby-Bauer Method)
- Drug synergy is when antibiotics combine and have a greater effect together than their individual effects summed
- If the drugs synergize the ‘halo’ between the two drugs will be bigger than the halo around the drug itself
Name the causative agent (organism) of amoebic dysentery (amebiasis).
12-3: Examination of Common Protozoans of Clinical Importance
Entamoeba histolytica
Amoebic dysentery is most common in areas with __________________________.
12-3: Examination of Common Protozoans of Clinical Importance
Poor water sanitation
Identification of the amoebic dysentery organism may be made by finding either trophozoites or _________________ in a _________________________.
12-3: Examination of Common Protozoans of Clinical Importance
Cysts
Stool Sample
Infection with the amoebic dysentery organism occurs when a human host ingests _______________ (stage) in _____________________________________.
12-3: Examination of Common Protozoans of Clinical Importance
__________________ of the amoebic dysentery organism are shed in the feces and may _______________________.
12-3: Examination of Common Protozoans of Clinical Importance
Cysts of the amoebic dysentery protozoan may persist in the original host, resulting in ____________________________________.
12-3: Examination of Common Protozoans of Clinical Importance
How does the organism that causes amoebic dysentery move through its environment?
12-3: Examination of Common Protozoans of Clinical Importance
The only ciliated human pathogen is (genus and species) __________________________________ and it causes the disease __________________________________.
12-3: Examination of Common Protozoans of Clinical Importance
- Balantidium coli
- Balantidiasis
____________________ in sewage-contaminated water are the infective form of Balantidium coli.
12-3: Examination of Common Protozoans of Clinical Importance
Cysts
Most infections of Balantidium coli are asymptomatic, however it can cause the following symptoms in some patients:
12-3: Examination of Common Protozoans of Clinical Importance
Diarrhea (bloody,invasive)
Name the organism that causes giardiasis.
12-3: Examination of Common Protozoans of Clinical Importance
Giardia lamblia (intestinalis)
Transmission of giardiasis typically involves:
12-3: Examination of Common Protozoans of Clinical Importance
Fecal or oral transmission due to drinking river/lake water
What is the infective stage of the organism that causes giardiasis?
12-3: Examination of Common Protozoans of Clinical Importance
Cyst
Diagnosis of giardiasis is made by identification of the protozoan trophozoites or ______________ in ____________________.
12-3: Examination of Common Protozoans of Clinical Importance
Cysts
Stool Sample
The STI/STD known as trichomoniasis is more common in ________________ than _________________.
12-3: Examination of Common Protozoans of Clinical Importance
Women
Men
Protozoal vulvovaginitis in humans is caused by (genus and species) ______________________________.
12-3: Examination of Common Protozoans of Clinical Importance
Trichomonas Vaginalis
Trichomonas is typically transmitted by _______________.
12-3: Examination of Common Protozoans of Clinical Importance
Sexual transmission
The ____________________ is the only stage of the Trichomonas life cycle and moves by _______________________.
12-3: Examination of Common Protozoans of Clinical Importance
Tryphozoite
Swimming
What drug is used to cure (treat) Trichomonas, Entamoeba, Balantidium, and Giardia?
12-3: Examination of Common Protozoans of Clinical Importance
Flagyl
(metronidazole)
The genus of the organism that causes African trypanosomiasis, a disease commonly known as ______________________________, is __________________________________.
12-3: Examination of Common Protozoans of Clinical Importance
African Sleeping Sickness
The intermediate host (vector) for African trypanosomiasis is the _______________________.
12-3: Examination of Common Protozoans of Clinical Importance
Tsetse fly
The stage of Trypanosomes that multiplies in the intermediate host is the ___________________, while the ___________________ stage multiplies in the human host.
12-3: Examination of Common Protozoans of Clinical Importance
Epimastigote
Trypomastigote
Which area or part of the body is affected during the advanced stages of infection that lead to coma and death in African Sleeping Sickness?
12-3: Examination of Common Protozoans of Clinical Importance
The Brain
Name a disease caused by Trypanosoma other than African sleeping sickness.* How is this disease transmitted?* In what part of the world is the disease most common?*
12-3: Examination of Common Protozoans of Clinical Importance
South America Sleeping Sickness
Transmitted by bug bite
South America
Name the genus and species of the 4 protozoans that cause malaria.
12-3: Examination of Common Protozoans of Clinical Importance
Plasmodium falciparum
Plasmodium malariae
Plasmodium ovale
Plasmodium vivax
The most severe form of malaria involves which organism? (genus and species)
12-3: Examination of Common Protozoans of Clinical Importance
Plasmodium falciparum
The arthropod vector for malaria is the _____________________________________.
12-3: Examination of Common Protozoans of Clinical Importance
Anopheles Mosquito
For malaria, the ________________________ stage of the pathogen is introduced into a human by a bite by the arthropod vector.
12-3: Examination of Common Protozoans of Clinical Importance
Sporozoite
For malaria, the _____________________ stage are released from the ruptured liver cells in humans, enter the blood, and infect erythrocytes.
12-3: Examination of Common Protozoans of Clinical Importance
Merozoites
Name two drugs in current use in the treatment of malaria.*
12-3: Examination of Common Protozoans of Clinical Importance
Doxycycline
Prophylactically
The sexual phase of the life cycle of Toxoplasma occurs in the _______________ where ____________________ are produced and shed in the ____________________.
12-3: Examination of Common Protozoans of Clinical Importance
Cat intestines
Oocysts
Feces
The more serious form of toxoplasmosis involves:
12-3: Examination of Common Protozoans of Clinical Importance
An infection of a fetus across the placenta that can result in still birth
Fetal infection with toxoplasmosis may result in:
12-3: Examination of Common Protozoans of Clinical Importance
Still birth
______________________ patients may suffer fatal complications from toxoplasmosis.
12-3: Examination of Common Protozoans of Clinical Importance
Immunocompromised or pregnant
List the gram reaction and morphology of the enteric bacteria.
4-5: MacConkey Agar
- Gram (+) poor growth or no growth, organism is inhibited by crystal violet and / or bile.
- Gram (-) Good growth, organism is not inhibited by crystal violet or bile.
MacConkey agar is used to isolate and differentiate members of the family Enterobacteriaceae based on their ability to ferment _____________________.
4-5: MacConkey Agar
Lactose
MacConkey agar is both a __________________ and a _________________ medium. Define both these terms.
4-5: MacConkey Agar
Selective: A medium that favors the growth of a specific type of microorganism (gram negative in this case)
Differential: A media containing ingriedients that help distinguish which bacteria can undergo a biochemical process (lactose fermentation in this case)
The sugar in MacConkey agar is _____________________.
4-5: MacConkey Agar
Lactose
Besides MacConkey, name 3 other tests that can give a presumptive indication that an organism is a coliform.
4-5: MacConkey Agar
- Membrane filter technique w/ endoagar
- Multiple tube fermentation method (LTB)
- Multiple tube fermentation (BGLB)
Besides nutrients, the sugar, the dye, and the pH indicator, MacConkey agar also contains:
4-5: MacConkey Agar
Bile salts to inhibit gram-positive growth
Why are bile salts and crystal violet included in MacConkey agar?
4-5: MacConkey Agar
To inhibit gam-positive growth
The presence of bile salts and crystal violet makes MacConkey agar a ___________________ medium.
4-5: MacConkey Agar
Selective
At a pH of less than 6.8, the pH indicator neutral red is ________________; at a pH of more than 6.8, it is _____________________.
4-5: MacConkey Agar
Red
Colorless
When bacteria are growing on MacConkey agar, what will cause the pH indicator to turn red?
4-5: MacConkey Agar
The pH becoming more acidic than 6.8 as a result of lactose fermentation
After growing on MacConkey agar, what do colonies of lactose nonfermenters look like? What do coliform colonies look like?
4-5: MacConkey Agar
- Nonfermenters retain their normal color or the color of the medium
- Fermenters turn pink then Red
What will gram-positive bacteria look like when plated on MacConkey agar?
4-5: MacConkey Agar
No Growth
If an organism grows on MacConkey agar but its growth is colorless, what can you conclude about this organism? What is the organism’s gram reaction? How do you know?
4-5: MacConkey Agar
- This organism is not a coliform as it could not ferment lactose and did not turn red
- Gram negative as gram positive will not grow
Any organism that grows well on MacConkey, regardless of the appearance of the growth, is gram ____.
4-5: MacConkey Agar
Negative
Explain what the results on your nutrient agar (NA) control plate prove in this experiment*
4-5: MacConkey Agar
Brilliant Green Lactose Bile (BGLB) broth and Lauryl Tryptose Broth (LTB) are both selective and differential. Describe how each broth is selective and how each is differential.
8-12: Coliform Test
BGLB:
Selective -
Differential -
LTB:
Selective -
Differential -
What is the concern if coliform bacteria are found in water?
8-12: Coliform Test
What is the purpose of the brilliant green dye and the oxgall in BGLB broth?
8-12: Coliform Test
Why is it important that BGLB contain lactose?*
8-12: Coliform Test
BGLB broth and LTB are both ______________________ and _______________________ media.
8-12: Coliform Test
Describe a + result in BGLB broth. Describe a negative result.
8-12: Coliform Test
Describe a + result in LTB. Describe a negative result.
8-12: Coliform Test
Why would it be important to determine if E. coli were present in a seawater sample?*
8-12: Coliform Test
Gram _______ bacteria will not usually grow in BGLB broth.
8-12: Coliform Test
What characteristics make an organism a coliform?
8-12: Coliform Test
Two other types of media that can be used to help determine if an organism is a coliform are ___________________ and _____________________.
8-12: Coliform Test
Name 4 genera of coliforms.
8-12: Coliform Test
Why is it that LTB is used to presumptively determine the presence or absence of coliforms, and BGLB is used to confirm the presence of coliforms?
8-12: Coliform Test
Give 2 reasons why sodium sulfite and basic fuchsin are included in Endo agar.
8-12 Endo Agar
- They inhibit the growth of gram-positive bacteria
- They both test for lactose fermentation
Endo agar inhibits the growth of _______________________ bacteria.
8-12 Endo Agar
Gram positive
The fermentable carbohydrate in Endo agar is _____________________.
8-12 Endo Agar
Lactose
What will colonies of lactose fermenters look like growing on Endo agar?
8-12 Endo Agar
Lactose fermentation -> Acids -> If rapid fermenter green metalic sheen, If slow fermenter dark pink/red
What appearance is created in this agar by lactose-fermenting organisms that produce large amounts of acid?
8-12 Endo Agar
- A metalic sheen green on the top of the agar and black appearance from the back of the plate
Name one coliforms (genus and species) that produce large amounts of acids when grown on Endo agar.
8-12 Endo Agar
E. coli
What appearance will be created by lactose non-fermenters growing on Endo agar?
8-12 Endo Agar
Light pink/colorless growth
Bacteria that will grow on Endo agar are Gram _______.
8-12 Endo Agar
Negative
Endo agar is used to detect fecal contamination in water and dairy products. What is the connection between fecal contamination and the bacteria that produce a metallic sheen on this agar?*
8-12 Endo Agar
Water and milk are tested for because E.coli lives in the intestines and their presence signals fecal contamination. The metalic sheen growth on endo agar is a visual indicator that the bacteria was a lactose fermenter and is presumptively a fecal coliform
If an organism that cannot ferment lactose grows on Endo agar, what is it using as a food source?* What kind of pH would this organism be expected to produce in the medium?* What will the colonies of this kind of organism look like?*
8-12 Endo Agar
Peptones, this organism would have a alkaline pH from peptone digestion. This organism would grow in light pink or colorless colonies
- It is important to note, nonfermenter could still be possible salmonella or shigella
What will be the appearance of a presumptive coliform organism growing on this agar? Why?
8-12 Endo Agar
- Metalic sheen green if the organims is a rapid fermenter of lactose
- Dark pink/red if the organism is a slow fermenter of lactorse
If an organism will not grow on Endo agar, that is a presumptive indication that the organism is __________________.
8-12 Endo Agar
Gram Positive
