on Bacterial Smear Preparation, Heat-Fixing
Principles, Acid-Fast and Negative Staining
Techniques, Morphology and Arrangement of Cocci,
Bacilli and Spiral Bacteria, Gram Reaction,
Chromophore Function, Microscope Utilization and
Resolution, Culture Media, Pure and Mixed
Cultures, Isolation Techniques, Selective and
Differential Media, Staphylococcus and
Streptococcus Identification, Pyogenic Bacteria,
Mannitol Salt Agar Interpretation, Aseptic and
Antiseptic Practices, Water Quality and Enteric
Pathogen Detection, Coliform Group Analysis, and
Microbial Ecology of Skin and Oral Cavities Exam
Questions Verified and Provided with A+ Graded
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What is a smear?
A thin film of material containing microorganisms spread over the surface of a clean microscope
slide
Sucess at bacterial staining depends on what?
preperation of a suitable smear of the organism
What is heat-fixing?
using a flame; the heating of a smear on a slide briefly and gently. partially melts the cell walls
of bacteria
What are the three things Heat-fixing does?
1: causes the cells to adhere to the slide so it wont wash off
2:Kills the microorganisms
3:Causes changes in the bacterial cells which causes them to stain better
,Hows does Heat-Fixing work?
It removes water from the bacterial cell, pores open in the cell so more stain can enter the cell
wall.
A good heat-fixes smear should be able to do what 2 things?
1. Must be able to withstand ane or more washings w/out the loss of microorganisms
2.Does not result in excessive cell distortion ***heat-fixing always results in some degree of cell
distortion,
Name 7 things that may go wrong in heat-fixing.
1.Over heat; incincerated cells will not stain
2.Under heat;if bacteria cells aren't killed, their ability to accept stain is altered
3.Must be Air-Dried; if not organism could be boiled and rupured and will not adhere to slidw
4.Too thick; light cannot pass, you cannot see individual cells
5.Too Thin; not enough cells to stain or see
6.Liguid broth;may be too little cells;use 2-3 loopfuls to compansate
7.Solid media (Agar);colonies are here and may have too many;dilute with 1-2 looful of distilled
water.
Steriliazation
It is an absolute value : 100%
-The complete destruction or removal of all microbes, including viruses(nonliving) &
endospores(Resting)
How are the organisms killed?
Steam; dry heat; incineration
Define Disinfection.
A process in which vegetative microorganisms are destroyed on non-living objects and surfaces
What does vegetative mean?
Actively growing
What is the number 1 agent for disinfection?
Bleach
What are the 3 definitions of Sepsis?
, 1:The growth of microorganisms in normally sterile tissues of the body
2:Decay, contamination,putrification
3:The presence of bacteria in blood that ate ectively multiplying (Serious)
Define ASEPSIS
A medical tem, any procedure that prevents the entrance of infectious agents into sterile tissue,
thus preventing infection.
What is Aseptic Techniques?
Practices used by micobiologists to exclude all organisms from contaminating media or
contacting living tissues
Antiseptics
Chemical agents ( often dilute disinfectants) that can be safely applied, externally, yo living
tissues (skin, mucous membranes) to destroy or inhibit vegetative bacteria
What is the #1 Antiseptic
Alcohol Pads
List 7 facts about Bacteria.
1. Most numerous and widely distributed organism
2.Found eveywhere in nature
3.Where microbes are normally found(like staph on skin) is presumably where they are adapted
to
4.They are not confined to to those areas and can easily move to other environments
5. They can be transfered easily
6.They can tolerate and take advantage of their new environment
7.Need Aseptic techniques for handling micobes
What is Media?
Any nutrient substance ( solid or liquid) that can support microbial growth
What is Inoculate?
To introduce microorganisms into normally sterile media
What is a Fomite?
Any non-living, inanimte abject that can carry (transmit) micobes
(and and ourselves are not fomites)