Lab Question Set 3 Flashcards by Rene Galindo

What is a selective medium?

4-4: Mannitol Salt Agar

A medium that allows for the growth of a type of bacteria while inhibiting others

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Explain how mannitol salt agar is selective.

4-4: Mannitol Salt Agar

The salt inhibits non-osmotolerant bacteria from growing. Only salt tolerant bacteria can grow on the medium

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What is a differential medium

4-4: Mannitol Salt Agar

A medium that allows for the growth of many bacteria but provides a visual distinction

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Explain how mannitol salt agar is differential.

4-4: Mannitol Salt Agar

Manitol is differential as it is only fermented by S. aureus

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Mannitol salt agar favors organisms capable of tolerating ______________________.

4-4: Mannitol Salt Agar

Salt

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Mannitol salt agar is used to differentiate pathogenic __________________________________ species, which ferment mannitol, from less pathogenic species that do not.

4-4: Mannitol Salt Agar

Staphylococcus aureus

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The pH indicator in mannitol salt agar is ___________________________.

4-4: Mannitol Salt Agar

Phenol Red

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The development of ________________ halos around bacterial growth on this medium is an indication that mannitol has been fermented with the production of ____________________.

4-4: Mannitol Salt Agar

Yellow
Acids

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Organisms plated on mannitol salt agar that cannot tolerate the level of salinity in the agar will show what kind of growth?

4-4: Mannitol Salt Agar

No growth

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Describe a negative result on mannitol salt agar (2 possibilities).

4-4: Mannitol Salt Agar

Red/pink growth: (-)
- Fermentation of mannitol did not occur
- Possible Staphyloccocus epidermis
No growth: (-)
- Not salt tolerant therefore no growth

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If bacteria grow on this agar and produce a pink color, is that a positive or a negative result? What causes the pink color?

4-4: Mannitol Salt Agar

Negative
- Bacteria were able to grow using peptones which resulted in the production of bases
- No mannitol was fermented

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True or false. If an organism grows on mannitol salt agar and produces a pink color, the organism cannot tolerate the sodium chloride concentration (osmotic pressure) in the medium.

4-4: Mannitol Salt Agar

False
- The organism was able to survive on the salt agar and grow but it did not ferment mannitol

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Why are selective and differential media like this one very helpful identifying bacteria?

4-4: Mannitol Salt Agar

Because they allow for a potentially unknown bacteria to be quickly identified. You can quickly determine if an organism is osmotolerant and if it is wheather or not it can ferment mannitol

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Name an organism (genus and species) that gives a positive result on the agar.

4-4: Mannitol Salt Agar

Staphylococcus aureus

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Your lab manual says that the nutrient agar control plate in this experiment, is “a comparison for growth quality.” Why is this useful?

4-4: Mannitol Salt Agar

To compare how the bacteria grew in a salty vs not salty environment

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Describe a + result on mannitol salt agar. What did the organism do, in order to produce this result?

4-4: Mannitol Salt Agar

Yellow growth
- The organism tolerated the salt medium
- The organism fermented mannitol
- The organism is likely (presumptive)S. aureus

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What is hemolysin?

5-25: Blood Agar

A virulence factor of Staphylococcus aureus
Exotoxin that uses RBC for nutrients and destroys them

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What does alpha hemolysis look like on blood agar? What do bacteria do to RBC’s to produce the typical color of alpha hemolysis? Give a genus and species.

5-25: Blood Agar

Green zones
Partial destruction of RBC
S. pneumoniae

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What does beta hemolysis look like on blood agar? What are bacteria doing to RBC’s to produce the typical appearance of beta hemolysis? What type of bacteria?

5-25: Blood Agar

Clear zones
Complete destruction of RBC
Group A and B Strep

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Which pathogen is an example of a beta hemolytic organism? What disease does this organism cause? What is the significance of being a carrier of this organism?

5-25: Blood Agar

Streptococcus agalactiae
- Part of normal floura but can be pathogenic for immunocompromised
- 25% of females are vaginal and/or anal carriers and can lead to major neonatal disease such as pneumonia, sepsis, and meningitis

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Define “normal microbiota” (“normal flora”). Give an example

5-25: Blood Agar

The natural bacteria that inhabits the digestive tract and does not cause illness under regular circumstances
Ex. S. agalactiae can cause neonatal disease such as pneumonia, sepsis or meningitis causing 50% mortality in those untreated

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Besides the organism mentioned in #20, another beta-hemolytic pathogen is the nosocomial organism that produces a golden-yellow pigment and also causes a food borne illness, __________________________.

5-25: Blood Agar

Staphylococcus aureus
Food poisoning

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What does it mean to say that an organism is “fastidious”?

5-25: Blood Agar

It requires very specific conditions to grow

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Hemolysins produced by bacteria of the genus Streptococcus are called ________________________.

5-25: Blood Agar

Streptolysin

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What is “presumptive identification” of a microorganism? What organism are we trying to presumptively identify in the bile esculin test? ## Footnote 4-3: Bile Esculin Test

Enterococcus faecalis

Esculin is an example of a type of molecule known as a glycoside; its 2 components are the sugar ________________________ and a compound called ___________________________. ## Footnote 4-3: Bile Esculin Test

Beta-D-Glucose Esculetin

The bile in bile esculin agar inhibits the growth of most __________________________ bacteria, except _____________________________ bacteria. ## Footnote 4-3: Bile Esculin Test

- Gram positive - Enterococcus

What is the source of bile in bile esculin agar? ## Footnote 4-3: Bile Esculin Test

Oxgall (bile salts)

Sodium azide is included in this agar to inhibit the growth of some ___________________ organisms. ## Footnote 4-3: Bile Esculin Test

Gram negative

When esculin molecules are split by bacteria, _______________________ reacts with ferric citrate and forms a ____________________ (color) phenolic iron complex. ## Footnote 4-3: Bile Esculin Test

Esculatin Brown

Describe a positive results in this experiment (include the time frame) ## Footnote 4-3: Bile Esculin Test

Medium darkens within 48H as esculin is metabolized

Describe a negative result in this experiment (include the time frame) ## Footnote 4-3: Bile Esculin Test

Medium remains the same color as esculin was not metabolized after 48H and no growth was observed

If an organism that cannot break down esculin grows on bile esculin agar, what would the organism have used as a food source?* Is this a positive or negative result?* Why?* ## Footnote 4-3: Bile Esculin Test

- Peptones - Negative because it is not E. faecalis but instead another type of Enterococcus

Explain how bile esculin agar acts as a differential medium, including the ingredients in the media that are differential. ## Footnote 4-3: Bile Esculin Test

- Esculin and Ferric citrate make it differential - Esculin will turn to esculatin if E. faecalis is present because of the enzyme esculinase - Ferric citrate is an esculin detector and will turn brown if +

Explain how bile esculin agar acts as a selective medium, including the ingredients in the media that are selective. ## Footnote 4-3: Bile Esculin Test

- Oxgall and sodium axide are selective as they only allow for growth of Enterococcus - Oxgall inhibits all G+ except Enterococcus - Sodium azide inhibits all G- - Only Enterococcus can resist the inhibitors

Explain how the ferric citrate in bile esculin agar allows you to observe a + result ## Footnote 4-3: Bile Esculin Test

Esculin ---(esculinase)---> esculatin Esculatin + Fe --> Dark Brown (+)

Describe some general characteristics of fungi? ## Footnote 12-1: Fungi (Yeast and Molds)

- Eukaryotic - Chitin Cell Wall - Heterotrophic

What are the two general categories of fungi and what characteristics are associated with them? ## Footnote 12-1: Fungi (Yeast and Molds)

Yeast: -Unicellular - Colonies resemble bacteria - Reproduce via budding (asym division) Molds: - Multicellular - Velvety/fuzzy - Hyphae filaments for nutrient absorption - Filamentous - thread like - Reproduce either sexually or asexually via spores

Why is Sabouraud Dextrose Agar used in this experiment? ## Footnote 12-1: Fungi (Yeast and Molds)

Low pH of 5-6 encourages fungal growth over bacteria

Which segment of the human population is most susceptible to infection by fungi? (5) ## Footnote 12-1: Fungi (Yeast and Molds)

- Diabetics - Immunocompromised - Catheterized patients - Infants - Women on antimicrobials

Members of the genus Penicillium are well known for producing the antibiotic ____________________. ## Footnote 12-1: Fungi (Yeast and Molds)

Penicillin

What are two examples of asexual spores that exist for filamentous fungus? ## Footnote 12-1: Fungi (Yeast and Molds)

Rhyzopus stolonifer: - Sporangium have sporangiospores Penicillium notatum: - Conidiospores (naked) are used for asexual reproduction

The HUrBi biplate contains selective media where Gram ______ bacteria grow on one side of the plate and Gram ______ bacteria grow on the other side. ## Footnote 6-2: HUrBi Urinalysis

Positive Neegative

Two selective ingredients contained in this medium that work to inhibit Gram (+) bacteria are _____________________________ & ______________________________. ## Footnote 6-2: HUrBi Urinalysis

-Sodium Azide - PEA

Two selective ingredients contained in this medium that work to inhibit Gram (-) bacteria are _______________________________ & _______________________________. ## Footnote 6-2: HUrBi Urinalysis

- Bile (oxgall)/synthetic desoxycholate - Sodium Sulfite

Chromagar ingredients are considered differential because they change ____________ based on distinct metabolic properties of various species of bacteria. What is the differential ingredient on the second side? ## Footnote 6-2: HUrBi Urinalysis

- Color - Lactose shows lactose fermentation (coliform)

The genus and species __________________ _________________ causes 90% of urinary tract infections (UTI’s). ## Footnote 6-2: HUrBi Urinalysis

E. coli

UTI’s are almost always caused by bacteria that are normal flora of the ___________________ tract (hint: it’s not the urinary tract). ## Footnote 6-2: HUrBi Urinalysis

Digestive

Lactose is contained in the Gram (-) side of the HUrBi plate because this fermentation of this sugar is important in the identification of _____________________ bacteria, which are members of the family Enterobacteraciae ## Footnote 6-2: HUrBi Urinalysis

Coliform

Greater than _ bacteria per mL of urine indicates a positive for UTI. ## Footnote 6-2: HUrBi Urinalysis

100,000

Although urine should be sterile when it is produced by the kidneys, why does urine from a healthy individual without a UTI still contain some bacteria? ## Footnote 6-2: HUrBi Urinalysis

Natural flora from urethra may contaminate sample

The number of bacteria/ mL of urine can be calculated by counting the number of _________________ of a given genus and species and multiplying by ____________________. ## Footnote 6-2: HUrBi Urinalysis

- Colony Forming Units (CFU) - 1000

Name the causative agent (genus and species) of schistosomiasis. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Schistosoma mansoni (trematode)

Schistosomiasis is most common in freshwater tropical areas with snails and _________________ contamination. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Fecal

Identification of the schistosomiasis organism may be made by finding eggs in the _____________________ or ______________________ of infected individuals. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Feces Urine

Infection with most helminths usually occurs when a human host ingests ___________________ (stage). ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Eggs

_______________ of the pinworm organism are present on the ___________________ region of the human body and may spread on clothing, bedsheets, towels, and fingers and survive for up to ______ weeks. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Eggs Perianal 2

Describe the way in which a physician would test someone for pinworm infection. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Cellophane tape on perianal region, Stain and put on slide

The most common helminth infection in the United States is _________________________. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Pinworm

Name the causative agent (genus and species) of pinworm. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Enterobius vermicularis (Nematode)

Hookworm is contracted by larvae that penetrate through human _____________________. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Foot

Adult hookworms suck ____________________ from the intestines and can cause anemia in severe infections. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Blood

The most prevalent helminth infection in the world is caused by the genus and species ______________________ _____________________. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Ascaris lumbaricoides (nematode)

Transmission of ascariasis occurs through the ingestion of _________________ in contaminated food or water. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Feces

Ingestion of undercooked pork may result in an infection with the helminth _________________________ _________________________ (genus and species). ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Taenia solium (cestode)

Ingestion of undercooked beef may result in an infection with the helminth ________________________ _________________________(genus and species). ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Taenia saginata (cestode)

Ingestion of Taenia solium eggs may result in a brain, eye, or muscle infection with the larval stage of this worm, the name for this infection is ____________________________. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Cysticercosis

An adult tapeworm has a head called a _____________________ and body parts that appear to be segmented that are referred to as gravid __________________________. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Scolex Proglottids

Flatworm helminths that are long and appear to be segmented are referred to as _______________________. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Cestodes (tapeworms)

Flatworm helminths that are non-segmented and often “leaf-shaped” are called ________________________. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Trematodes (flukes)

Roundworm helminths are referred to as ______________________. ## Footnote 12-4 Examination of Common Helminths of Clinical Importance

Nematodes

What are the two groups that leukocytes are divided into? How do we distinguish between these two groups? ## Footnote 11-1: Differential Blood Smears

Granulocytes: Have prominent granules - Neutrophils - Eosinophils - Basophils Agranulocytes: Lack granules - Lymphocyte - Monocyte

What are the three basic types of granulocytes? ## Footnote 11-1: Differential Blood Smears

Neutrophils: - 55-65% - 12-15 um -Phagocytosis and digestion Eosinophils: - 1-3% - 12-15 um - Phagocytic, worms, allergies Basophils: - 0.5-1% - 12-15 um - Release histamine during allergic response

What are the two types of agranulocytes? ## Footnote 11-1: Differential Blood Smears

Lymphocyte: - 25-33% - 7-18 um - Aquired immunity (B&T) Monocyte: - 3-7% - 12-20 um - Macrophage (phagocytosis)ZZ

An increase in which type of white blood cell (WBC) is indicative of a systemic bacterial infection? ## Footnote 11-1: Differential Blood Smears

Neutrophils

Because of the variation in nuclear appearance for neutrophils, they are sometimes referred to as ___________________________________________ ## Footnote 11-1: Differential Blood Smears

polymorphonuclear neutrophils (PMNs) or polys

## Footnote 11-1: Differential Blood Smears

List the 5 types of WBCs IN ORDER, from most abundant in the blood to least abundant. ## Footnote 11-1: Differential Blood Smears

1. Neutrophils 2. Lymphocytes 3. Monocytes 4. Eosinophils 5. Basophils

What total magnification should you use to view the blood smears? ## Footnote 11-1: Differential Blood Smears

1000x

__________________________ is a general term applied to any agglutination test in which the clumping of red blood cells indicates a positive reaction. ## Footnote 11-5 Blood typing

Hemeagglutination

If a person has an A antigen on their RBC, they are type _______ blood and they produce ____________ antibodies. ## Footnote 11-5 Blood typing

A B

What antigen is expressed on type B blood cells? What antibodies does a person produce if they are type B blood? ## Footnote 11-5 Blood typing

- B antigen - A antibodies

If an individual lacks BOTH the A and B antigen on their RBC, what blood type are they? What antibodies will that person produce? ## Footnote 11-5 Blood typing

-O - Will produce A and B antibodies

If you perform an agglutination with anti-A antiserum and you see agglutination, and then with type-B anti-serum and you don’t see agglutination, what blood type is the person? ## Footnote 11-5 Blood typing

Type A

If you get agglutination after adding the anti-Rh antiserum, is the person Rh positive or negative? ## Footnote 11-5 Blood typing

Rh +

What blood type is the universal donor, including the Rh factor? What blood type is the universal recipient, including the Rh factor? ## Footnote 11-5 Blood typing

Universal donor: O- Universal recipient: AB+

## Footnote 11-5 Blood typing

Lab Question Set 3 Flashcards

(87 cards)