Chapter 2: Tools of the Laboratory Flashcards
The Five I’s
Inoculation Incubation Isolation Inspection Identification
Culture
the propagation of microorganisms with various media
Medium
a nutrient used to grow microorganisms outside their natural habitat
Inoculation
the implantation of microorganisms into or onto culture media
Usual incubation temperatures
between 20°C and 40°C
Pure Culture
container of medium that grows only a single known species
Mixed Culture
Contains two or more identifiable species
Contaminated Culture
Was once pure or mixed, but has since been contaminated; can’t identify all the organisms
Physical States of Media
liquid semisolid solid (can be converted to liquid) solid (cannot be liquefied)
Agar
complex polysaccharide from the alga Gellidium; liquefies at 100°C and solidifies at 42°C and can be poured in liquid form that will not harm the microbe or the handler
General Purpose Media
Grows a broad spectrum of microbes; complex; Nutrient agar, broth, brain-heart infusion, & TSA
Selective Media
Contains one or more agents that inhibit growth of certain microbes but not others; for samples containing dozens of different species (saliva, skin, water, soil)
Enriched Media
Contains complex organic substances; for growing certain species (fastidious microbes); Blood agar, Chocolate agar
Differential Media
Allows multiple types of microorganisms to grow; causes different reactions (dyes make microorganisms easily identifiable)
Transport Media
Used to maintain and preserve specimens that have to be held for a period of time before clinical analysis; also used to sustain species that die quickly
Reducing Media
Contains sodium thioglycollate or cystine that absorbs oxygen or slows the penetration of oxygen; grows anaerobic bacteria or determines oxygen requirements of isolates
Carbohydrate Fermentation Media
Contains sugars that can be fermented (converted to acids) and a pH indicator to show this reaction; identifies bacteria and fungi
Streak Plate
Easy and effective; method of choice
Loop Dilution
Allows colonies to grow deep in the solution, not just on the surface
Viruses measurements
between 20 – 800 nm
Smallest bacteria measurements
200 nm
Protozoa and Algae measurements
3-4 mm
Objective Lens
closest to the specimen, forms the initial image called the real image
Ocular Lens
forms the second image called the virtual image that will be received by the eye and converted to the retinal and visual image