Lesson 12 Flashcards
Laboratory diagnosis of an infection is usually confirmed by isolating and culturing microorganisms in what kind of media?
artificial media
are cultured in either liquid (broth) or on solid (agar) artificial media.
Bacteria and fungi
-, developed the Petri dish (plate), a container for solid culture media.
Richard Petri
A nutrient material prepared for the growth of microorganisms in a laboratory
Culture medium
When microbes are introduced into a culture medium to initiate growth,
Inoculum
- The microbes that grow and multiply in or on a culture medium
culture
-: is the process of growing microorganisms in culture
Cultivation
- taking bacteria from the infection site
in vivo environment
- by some means of specimen collection and growing them in the artificial environment of the laboratory
the in vitro environment
- a laboratory culture containing a single species of organism.
Pure culture
Purposes of bacterial cultivation
i. To grow and isolate all bacteria present in an infection.
ii. Infection and contaminants or colonizers: To determine which of the bacteria that
grow are most likely causing infection and which are likely contaminants or
colonizers.
iii. Identification and characterization: To obtain sufficient growth of clinically relevant
bacteria to allow identification and characterization.
Purposes of bacterial cultivation
i. To grow and isolate all bacteria present in an infection.
ii. Infection and contaminants or colonizers: To determine which of the bacteria that
grow are most likely causing infection and which are likely contaminants or
colonizers.
iii. Identification and characterization: To obtain sufficient growth of clinically relevant
bacteria to allow identification and characterization.
is often suitable for culture media, particularly if it has a low
mineral content, however glass-distilled or demineralized water is best used.
Tap water
is prepared from a variety of seaweeds and is now
universally used for preparing solid media
Agar
most bacteriological agars melt at what temperature ?
95°C
Agar solidify only when
cooled in what temperature?
42°C
almost universal ingredient of common media is . It is a
complex mixture of partially digested proteins.
peptone
The important constituents of peptone?
peptones
proteoses
amino acids
a variety of inorganic salts including phosphates,
potassium and magnesium,
certain accessory growth factors such as nicotinic
acid and riboflavin
: It contains a wide range of amino acids, growth factors and
Inorganic salts. is used mainly as a comprehensive source of growth
factors and may be substituted for meat extract in culture media.
Yeast extract
It consists mainly of maltose (about 50%), starch, dextrins and
glucose, and contains about 5 percent of proteins and protein breakdown products,
and a wide range of mineral salts and growth factors
Malt extract:
There are use for enriching culture media. Either human or animal blood can be used
Blood and serum
-the earliest culture media.
Liquid media
-The original media used by Louis Pasteur was liquids such as what?
Urine and broth
are dissolve in water, and bacterial growth is indicated by a change in broth appearance from clear to turbid
Broth media nutrient
-Uses of broth media nutrient
For obtaining bacterial growth from blood and water when large volume has to be tested
Preparing bulk of cultures of antigens or vaccines
-are made by adding a solidify agent to the nutrients and water
Solid media/agar
-are made by adding a solidify agent to the nutrients and water
Solid media/agar
-most common solidifying agent
Agarose