Microbiology-chapter 4

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you know the drill

Sterilization

destruction or removal of all microorganisms by use of heat, radiation, filtration, or chemical methods, kills everything

Disinfection

use of physical process or chemical agent to destroy vegetative microbes and viruses. Applied to inanimate surfaces, medical equipment, and man-made objects.

Antiseptics

used to disinfect skin

Sanitization

-Any cleaning technique that mechanically removes microorganisms and other debris to reduce contamination to safe levels. Uses compounds such as soap.
-Used in restaurants, dairies, breweries, and other food industries

Deceration

-Numbers of microbes on human skin are reduced by: scrubbing, immersion in chemicals, or both.

Media

Provide nutrients for growth of organisms. At least 500 different types are used.

Liquid media

-water-based solutions that don't solidify at temperatures above freezing
-tend to flow freely when container is tilted
-Growth occurs throughout container
-these media are called broths

Semisolid media

-clot like at room temperature
-contain any amount of solidifying agent-agar or gelatin
-Used to determine motility of bacteria
-Inoculated by stabbing the center of the medium with inoculating needle

Solid media

-Dispensed in Petri plates
-provide firm surface for growth
-discrete colonies
-Isolation and culturing of bacteria and fungi
-contains agar

Chemical content of media

-termed synthetic
-contain pure organic and inorganic compounds
-chemical content specified by exact formula
-standardized and reproducible

Complex media

-one or more components of a given media isn't chemically defined
-nonsynthetic
-cannot be represented by an exact chemical formula
-extracts from animals, plants, yeast, cells, tissues, ect.

General purpose media

-grow broad spectrum of microbes that don't have special growth requirement
-nutrient agar and broth
-brain-heart infusion agar
-Trypticase soy agar (TSA)

Enriched media

-contain complex organic substances such as blood, serum, hemoglobin, or special growth factors
-blood agar
-Thayer-Martin agar
-Chocolate agar

Selective media

-Contain one or more agents that inhibit the growth of a certain microbe or microbes
-favor or select a certain microbe and allows it to grow
-Isolation of a specific type of microorganisms from a complex sample such as feces, saliva, skin, water, and soil

Differential media

-grow several types of microorganisms
-differences show up as variations in colony size or color, in media color change

reducing medium

-contain substances that absorb oxygen or slow the penetration of oxygen in a medium

Identification

-determination of the type of microbe
-staining
-specialized tests: biochemical, Immunological, genetic

Wet mounts

-Live samples are placed on slides

Smear

-a thin film of a solution of microbes on a slide

Negative stain

-indirect staining process
-acidic stains-india ink or nigrosin
-dark background against organism
-doesn't require fixation of smear

Simple stain

-single stain applied to specimen after fixation onto the slide
-most commonly include:methylene blue, crystal violet

Differential stain

-uses more than one stain to differentiate cellular components
-allows differentiation between bacterial species

Gram stain

-most widely used differential stain in microbiology
-most reliable with young bacterial cultures

Color of gram positive staining

purple

color of gram negative staining

red/pink

Acid fast staining

-stained with carbolfuchsin and treated with acid-alcohol
-________ bacteria remain red
-non________ are blue when counterstained with methylene blue
-used for tuberculosis (know this)

negative stain

-used to demonstrate the presence of capsules or difficult to see structures such as spirals

Endospore stain

-used to demonstrate the presence of endospores

Flagella stain

-used to demonstrate the presence of flagella

Wright stain

-differential stain used for staining blood smears
-hematology testing

Morphological characteristics

-What does it look like on the plate?
-color, size, shape, ect
-Appearance or growth on selective and differential media

Morphology

-used for preliminary identification of bacteria, fungi, parasites
-bacilli-rods
-cocci-circles
-Sprilla

Nutrient agar

-commonly used general growth medium

Blood agar plates (BAP)

-differentiate between species based on their ability to produce hemolysins

Chocolate agar (CHOC)

-Lysed blood agar plate
-used for growing difficult respiratory bacteria

Thayer-Martin agar (TM)

-chocolate agar with antibiotics for isolatin of Neisseria gonorrea and N.meningitides

MacConkey agar

-used to differentiate between gram-positive and gram-negative bacteria

Identification

-determination of the type of microbe
-staining
-specialized tests:biochemical, immunological, or genetic

most common stain

gram stain

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