Ch 2: Tools of the Laboratory

What is inoculation?

Clinical specimens are obtained from body fluids, discharges, anatomical sites, or diseased tissue.

__ is to grow microorganisms.

Culture

__ are the nutrients for the growth of microbes.

Medium (plural, media)

__ is a small sample of microbes.

Inoculum

__ is the introduction of an inoculum into media to culture microbes.

Inoculation

__ is a temperature-controlled chamber to encourage the multiplication of microbes.

Incubator

Temperatures used in laboratory propagation of microorganisms are __.

20°C to 45°C.

Atmospheric gases such as __ or __ may be required for the growth of certain microbes.

oxygen, carbon dioxide

During __, microbes grow and multiply, producing visible growth in the media.

incubation

__ is a growth media contains only a single known species or type of microorganism.

Pure

__ is a container that holds two or more identified, easily differentiated species.

Mixed

__ was once a pure or mixed culture, but has since had __ (unwanted microbes) introduced into it (like weeds in a garden)

Contaminated, contaminants

Culture media may be contained in __.

test tubes, flasks, & petri dishes.

Media may inoculated with __.

loops, needs, pipettes, & swabs.

__ technique is necessary.

Sterile

What are the three physical states?

liquid, solid, semisolid

What has the following characteristics:

• Complex polysaccharide isolated from Gelidium

• Solid at room temperature

• Liquefies at 100°C, solidifies at 42°C

• Flexible and moldable

• Not a digestible nutrient for most microorganisms!!

Agar

Which chemical content of media:

• Composition is precisely chemically defined

• Contain pure organic and inorganic compounds that vary little from one source to another

• Molecular content specified by means of an exact formula

defined (synthetic)

Which chemical content of media:

• One or more components is not chemically defined

• Contains extracts of animals, plants, or yeasts

• Blood, serum, meat extracts or infusions, milk, yeast extract, soybean digests, and peptone

complex

A medium can be both __ and __.

selective, differential.

Which type of media:

• Contains a substance that absorbs oxygen or slows the penetration of oxygen

• Important for growing anaerobic bacteria

Reducing medium

Which type of media:

• Used to maintain and preserve specimens that have to be held for a period of time before clinical analysis

Transport media

Which type of media:

• Contains sugars that can be fermented with a pH indicator to show this reaction

Carbohydrate fermentation media

Which type of media:

• Used by technologists to test the effectiveness of antimicrobial drugs

• Used by drug manufacturers to test the effectiveness of disinfectants, antiseptics, cosmetics, and preservatives on microorganisms

Assay media

__ requires the following:

• A medium with a firm surface

• A Petri dish

• An inoculating loop

Isolation

__ is a macroscopic cluster of cell appearing on a solid medium arising from the multiplication of a single cell.

Colony

The dimensions of macroscopic organisms are given in __ and __.

centimeters (cm), meters (m).

Protozoa and algae measure __.

3 to 4 mm.

Yeast are generally __.

3 to 4 µm

The smallest bacteria measure around __; largest around __.

200 nm, 750 um

Most __ measure between 20 nm and 400 nm; some can be as big as 800 nm or 1500 nm (as big as cells).

viruses

What are order of microbes from smallest to largest?

viruses, bacteria, yeasts, protozoa

__ is formed by the objective.

Real image

__ is formed when the image is projected through the microscope body through the ocular lens.

Virtual image

__ is the capacity of an optical system to distinguish two adjacent objects or points from one another.

Resolution

Resolving power of the human eye is __.

0.2 mm.

__ consists of a drop or two of culture placed on a slide and overlaid with a cover slip.

Wet mount

__ is a drop of culture is placed in a concave (depression) slide, Vaseline, adhesive or sealant, and cover slip are used to suspend the sample.

Hanging drop

__ is any procedure that applies colored chemicals (dyes) to specimens.

Staining

__ have a positive charge.

Basic dyes

__ have a negative charge.

Acidic dyes

__ dye sticks to the specimen and gives it color.

Position stain

__ does not stick to the specimen but settles some distance from its outer boundary forming a silhouette.

Negative stain

__ only require a single dye and uncomplicated procedure.

Simple stain

__ use two differently colored dyes: the primary dye and the counterstain.

Differential stain

Different results in the __ stain are due to differences in the structure of the cell wall.

gram

The __ stain remain the universal basis for bacterial classification and identification.

gram

Endospore stain distinguishes between __ and __ cells.

endospores, vegetative

Which special stain has the following:

• Used to observe the microbial capsule, an unstructured protective layer surrounding the cells of some bacteria and fungi

• Negatively stained with India ink

Capsular staining

Which special stain has the following:

• Used to reveal tiny, slender filaments used by bacteria for locomotion

• Flagella are enlarged by depositing a coating on the outside of the filament and then staining it

Flagellar staining

Identify the following staining techniques as simple, differential, or special.

• capsule stain

special

Identify the following staining techniques as simple, differential, or special.

• acid-fast stain

differential

Identify the following staining techniques as simple, differential, or special.

• crystal violet

simple

Identify the following staining techniques as simple, differential, or special.

• Gram stain

differential

Identify the following staining techniques as simple, differential, or special.

• flagellar stain

special