Activity 8-12 Flashcards by IVAN LESTER CALAR

-polysaccharide derived from red algae is added to solidify nutrient liquid media

-allowed specimen to be spread across the surface of the medium and grown to produce single colonies, isolating the various microorganisms which are present

-suited as a solidifying agent because it will not melt until the medium is heated to near boiling(95degree C- 100 degree C) but will remain melted untilcooled (42 degree C)- agar solidifies at this temperature

-allow strict control of the growth factors

Agar

How well did you know this?

Not at all

Perfectly

Culture media are sterilized by?

Autoclaving

How well did you know this?

Not at all

Perfectly

Media that contains heat labile components like G, A, U, S, B ARE NOT AUTOCLAVE. What are they?

glucose, antibiotics, urea, serum, blood

How well did you know this?

Not at all

Perfectly

Once the media is prepared, it is held at ________ degrees in the refrigerator for ________ weeks. How many degrees and weeks?

4-5°C;1-2weeks

How well did you know this?

Not at all

Perfectly

For Blood Agar, cool melted agar base to about 45-50°C before adding whole blood (5ml/100ml of blood agar base)

Fact

How well did you know this?

Not at all

Perfectly

Mix blood with agar by rotating media and making figures of 8, w/o producing bubbles

Fact

How well did you know this?

Not at all

Perfectly

For Chocolate Agar, cool agar base to about 50- 60 degreeC before adding whole blood.

Fact

How well did you know this?

Not at all

Perfectly

What will lyse RBC giving the medium a chocolate brown color?

High Temperature

How well did you know this?

Not at all

Perfectly

the lysis releases intracellular nutrients such as ________ and ____________?

hemin (X Factor); coenzyme Nicotinamide Adenine Dinucleotide (NAD or V Factor)

How well did you know this?

Not at all

Perfectly

What will inactivates the enzymes NADases that hydrolyze “V Factor”

Heat

How well did you know this?

Not at all

Perfectly

CONTROL of microorganisms is essential in order to prevent the transmission of diseases and infection, stop decomposition and spoilage, and PREVENT UNWANTED MICROBIAL CONTAMINATION microorganisms are controlled by means of physical and chemical agents

Autoclave

How well did you know this?

Not at all

Perfectly

Physical Agents?

High or low temperature, Dessication, Osmotic Pressure, Radiation, Filtration

How well did you know this?

Not at all

Perfectly

chemical agents?

disinfectants, atibiotics, chemoterapeutic antimicrobial chemicals

How well did you know this?

Not at all

Perfectly

Fact

Microorganisms have a minimum, an
optimum, and a maximum temperature for growth

How well did you know this?

Not at all

Perfectly

Temperatures below the minimum usually have ______ action on microorganisms

Static

How well did you know this?

Not at all

Perfectly

they inhibit microbial growth by slowing down metabolism but do not necessarily kill the organism

Static Action

How well did you know this?

Not at all

Perfectly

Temperatures above the maximum usually have __________ since they denature microbial enzymes and other proteins.

Cidal action

How well did you know this?

Not at all

Perfectly

is a very common and effective way of controlling microorganisms

Temperature

How well did you know this?

Not at all

Perfectly

vegetative microorganisms can generally be killed at _________ with moist heat.

50-70°C

How well did you know this?

Not at all

Perfectly

Fact

Bacterial endospores are very resistant to heat and extended exposure to much higher temperature is necessary for their destruction

high temperature may be applied as either moist heat or dry heat

How well did you know this?

Not at all

Perfectly

is generally more effective than dry heat because of its ability to penetrate microbial cells

kills organism by denaturing their
protein (causes proteins and enzymes to lose their three dimensional functional shape).

it also may help lipids in cytoplasmic membranes

Moist Heat

How well did you know this?

Not at all

Perfectly

Autoclaving employs?

Steam under pressure

How well did you know this?

Not at all

Perfectly

During autoclaving, the materials to be sterilized are placed under ___ pounds per square inch of pressure in a pressure cooker type of apparatus.

15; raised to 121°C; 15 minutes

How well did you know this?

Not at all

Perfectly

temperature to sufficiently kill bacterial endospores

121°C

How well did you know this?

Not at all

Perfectly

is cidal for both vegetative organisms and endospores is the most common method of sterilization for materials not damaged by heat.

Autoclaving

(Parts of the pressure cooker) holds the chamber

Body

(Parts of the pressure cooker) where apparatus or media to be sterilized is places

Chamber

measure the pressure in the chamber

Pressure Gauge

regulates the pressure inside the chamber

Pressure Relief Valve

an exhaust for steam when pressure is reduced

Air Evacuation Valve

gives simultaneous readings for pressure and temperature

Pressure Temperature Thermometer

fasten the lid orcover to the body

Wing nut compression screews

the streak plate technique is used to spread million of cells over the surface of a solid medium so that some individual cells are deposited at distance from all others. - these cells grow and reproduce, forming an isolated colony.

Isolation Techniques

Example of streaking method of isolation:

- Four way streak method - Urine culture streak method - Three way streak method - S- Streak method

For incubation, what are the degrees for it and until what time?

place the plate in 35-37 degree celcius incubator for 18-24 hrs

T Streak Method

- draw T on the bottom of petri dish - aseptic technique is observed - the loop should be parallel to agar surface to prevent digging into the agar - streak about half of agar plate -make one streak into the inoculated portion of the plate. finish b streaking about 1/4 of uninoculated plate.

Pour Plate Technique

One in which a small amount of inoculum from broth cultures/liquid specimen is added by pipette into a molten, cooled agar medium (45-50 degree C) - pour plates allow microorganisms to grow broth on the surface within the medium. - most of the colonies grow within the medium and are small in size; few that grow on the surface are oyn the same size and appearance as those on a streak plate.

tube media maybe in form of _______,_____,______ depending on the purpose of the inoculation and the type of medium used, inoculating loop or wire loop may be used.

solid agar slants, semi solids or broths,

place the loop at the base of the slant surface and draw it up the agar surface while moving it from side to side.

Agar slants

insert the inoculating needle and stab it in the center of the agar tube to the bottom. draw the needle out carefully, keeping it straight.

Agar butts

Used to test large volume of liquid samples, including water and filterable beverages

Membrane Filtration Method

used as enrichments and general cultivation

Innoculation of Broth Media

contains two or more bacterial species that are known and can be easily separated based on cultural or biochemical characteristics.

Mixed Culture

provides a means for maintaining adequate nutrition for the organisms so they can continue to survive

Culturing Techniques

Culturing procedures

Isolation techniques

is a colony that is not touching any other colonies and assumed to be a pure culture. these colonies are easily accessible for performing staining identification processes.

Isolated Colony

is a very homogeneous population formed by the progeny of a single bacterium

Bacterial Colony

Seven macroscopic characteristics of bacterial colonies

Size, Shape(Form), Margin, Surface Texture, Pigmentation, Transmitted light/ optical property, & Elevation

whenever possible measure colony diameter and express in mm

Size

- punctiform- to small to measure - moderate- 1mm-5mm - large- 5-10mm

Shape/Form

Circular, Irregular, Filamentous, Rhizoid

outer edge/periphery of the coloy

Margin

- entire- even - Undulate/wavy - Filamentous - Erose/serrated - Lobate/Curled

Surface Texture

- Rough/coarse - smooth/shiny - mucoid - wrinkled

the color as precisely as possible

Pigmentation

Transmitted light/ optical property:

Transparent, Opaque, Transluscent

the light passes to the colony; clear

Transparent

if the light does not pass through the colony

Opaque

if the light can pass in a diffuse manner so that a colony is illuminated but objects at the other side cannot be seen directly

Translucent

Elevation

- flat raised - convex/dome shape - umbonate

enriched, general supportive and differential medium used to grow a variety of fastidious microorganism such as Streptococcus. - can function as differential media because it can demonstrate different types of hemolysis such as: Beta, Gamma(Non), Alpha hemolysis

Blood Agar

complete lysis of RBC by streptolysin O and streptolysin S enzymes; which produces clear halo around the colonies

Beta hemolysis

incomplete lysis of rbc resulting in breakdown of hemoglobin, which produces greenish halo around bacterial colonies

Alpha Hemolysis

no lysis of rbc; no significant change in color of the agar surrounding the colonies

Gamma (Non) Hemolysis

provide serum ingredients and erythrocytes which would allow differentation of microorganisms growing based on their hemolytic reactions.

Blood

-selective media -grows only staphylococcus bacteria -7.5% salt is inhibitory to most other bacteria - it is a nutritive medium due to its contents of peptones and beef extract, which supply essential growth factors such as nitrogen, carbon, sulfur and trace nutrients - also a differential media used to distinguish between Staphylococcus aureus and other Staphylococcus spp.

Mannitol Salt Agar (MSA)

Fact

mannitol fermenation with subsequent acid production by S. aureus is indicated by a change in the color of the phenol red indicator to yellow

the name of the enzyme found in most bacteria which initiates the breakdown of hydrogen peroxide (H202) into water (H20) and free oxygen (02)

Catalase

Fact

Most bacteria are catalase (+)

Catalase (-) certain genera that dont carry out aerobic respiration, such as

Streptococcus, Lactobacillus, and Clostridium

The catalase test differentiates the

Staphylococci Streptococci

Streptococci catalase ?

Staphylococci catalase ?

Oxygen bubbling in catalase test?

Positive

Little to no bubbling in the catalase test?

Negative

Little to No bubbling in catalase test

Negative

Little to No bubbling in catalase test

Negative

Fact

Do not pick colonies from BAP for catalase test because RBC contains catalase. This may lead to false positive reaction.

- used to differentiate Staph aureus (coagulase positive) from coagulase negative staphylococci. - S. aureus produces two forms of coagulase: •bound coagulase •free coagulase

Coagulase Test

is bound to the bacterial cell wall and directly reacts with fibrinogen.

Bound coagulase or clumping factor

macrocopic clumping in 10-15 secs

Positive

No clumping

Negative

Activity 8-12 Flashcards

(82 cards)