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39 terms

Microbiology-chapter 4

you know the drill
STUDY
PLAY
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