Micro 150 CH 3.1 Quiz + HW WIP

The identities of microorganisms on our planet

are still mostly unknown.

Not only is blood agar an enriched medium that can support fastidious organism growth, but it can also serve as a differential medium in the identification of streptococcal species because of the presence of red blood cells that can be destroyed by an organism's hemolysins. Looking at this photo, how could you describe the organism growing on the surface of this blood agar plate?

Beta-hemolytic

If a Gram stain result is unclear, which of the following should be considered?

All of the choices are correct.

A fastidious organism must be grown on what type of medium?

Enriched medium

Choose the description that best fits a medium that has been designed to support the growth of MRSA (methicillin-resistant Staphylococcus aureus) while inhibiting all species and strains of other bacteria.

Selective

Viruses are commonly grown in/on

animal cells or tissues.

Choose the term that describes motility media.

Semisolid

Select the type of media where the chemical composition is precisely known

Defined

Some organisms ferment certain carbohydrates to produce an acidic byproduct while others don’t. What component of mannitol salt agar makes this media differential?

Both the mannitol and the phenol red

E. coli is an intestinal organism, and Staphylococcus epidermidis resides on the skin. What do you hypothesize will occur when both are inoculated onto mannitol salt agar?

The salt inhibits the growth of E. coli which is not a halophile; the S. epidermidis will grow.

Choose the media categorization that includes enriched, selective, and differential media.

Media categorized by its purpose

Enterococcus faecalis broth

Sodium azide allows for the growth pf fecal enterococci

MacConkey Agar

Bile and crystal violet allow for the growth of gram-negative enterics

Lowenstein-Jensen

Malachite green allows for the growth of Mycobacterium

Sabouraud's Agar

Acidic media which allows for the growth of fungi

Blood Agar

Demonstrates hemolysis of erythrocytes by Streptococcus species

Mannitol Salt Agar

Phenol red allows for identification of Staphylococcal species

Triple-sugar Iron Agar

Identification of hydrogen sulfide producing bacteria

MacConkey Agar

Neutral red allows for identification of lactose fermenting bacteria

Range of the human eye can view

1 mm

Range of a light microscope can view

100 um

10 um

1 um

Range of an electron microscope

200 nm

100 nm

10 nm

1 nm

Requires special microscope to view

0.1 nm

What are the 5 I’s

1. Inoculation

2. Incubation

3. Isolation

4. Inspection

5. Identification

Inoculation

Sample is spread onto several types of culture media or growth medium via inoculation. Medium can be solid or liquid or a live animal such as a chicken embryo

Incubation

Culture media are placed at the proper growth temperature and allowed time to grow.

Isolation

A colony is spread onto a new plate of media using a quadrant streak method.

Inspection

Cultures are observed macroscopically and Microscopically. Possibly with the aid of staining

Identification

The identity of the isolated microbe is determined. Usually to the special level inspection may be enough to identify some microbes. Techniques include Biochemical test, Immunologic tests, and genetic analysis (A variety of biochemical tests are used to characterize a microbe.)

Loop Dilution/Pour Plate

Pour plating involves adding a sample to liquefied agar, and then pouring the agar into a plate to solidify.

Streak Plate

Involves diluting one inoculum across the surface of a plate using a quadrant pattern

Spread Plate

Involves adding a sample to the surface of a plate and then using a L-shaped glass rod to evenly spread across the surface.

Types of Media physical states

Liquid

Semisolid

Solid (can become liquid)

Solid (cannot be liquefied)

Media Functional Types

General purpose

Enriched Selective

Differential Anaerobic growth

Speciment transport

Assay

Enumeration

Types of Media Chemical Composition

Chemically defined

Complex, not chemically defined

Mannitol salt agar is defined as both a selective and a differential agar since it selects against non-halophiles and allows the researcher to distinguish between organisms that vary in their ability to ferment mannitol. T/F

True

The terms "sterile" and "pure" can be used interchangeably when discussing cultures, because they both refer to a culture that has not been contaminated. T/F

False

Chocolate agar purpose

Enriched

Mannitol salt sugar purpose

Selective and differential

Nutrient Agar purpose

General-purpose

Phenylethanol agar purpose

Selective

Reducing media

Growing anaerobic microbes

Urea agar purpose

Differential