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What is the purpose of Clinical Microbiolist?
- Asist physicians in diagnosis and treatment of infectous disease
- Determine etiology
- Determine susceptibility of etiologic agent to antibiotics
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Clinical Microbiologist methods
- culture
- direct detection
- serology
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Cell culture can be performed with:
- living cells
- viruses
- highly fastidious bacteria
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Cell culture is useful because it allows for:
observation fo cytopathic effects
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Arificial culture medium is characterized by:
- non-living
- liquid or solid
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Artificial culture medium is useful for cultivating:
bacteria and fungi
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Liquid broth media is composed of:
- nutrients for growth
- e.g. thioglycollate and breain heart infusion
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Disadvantages of liquid broth media are:
purity issues
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Growth can be seen in Liquid broth media by observing the:
clarity
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Esmaples of liquid broth media are:
heart brain infusion and thioglycollate
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Turbidity on liquid broth indicates:
growth
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Turbidity of broth increase 1:1 with what other aspect?
Bacteria/mL
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Detecting mixed cultures:
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Solid media is made from
agar
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agar forms a solid above what temperature?
greater than or equal to 45 degrees celcius
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a colony begins with:
a single organism
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Advantages of sold media:
- can detect purity
- can detect morphology
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Disadvantages of soldi media are:
sensitivity and standardization
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Blood and chocolate agars are examples of:
solid media
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Examples of solid media are:
blood and chocolate
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Enriched media is used for:
nutritionally fastidious organisms grow on
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Examples of Enriched media are:
chocolate and blood agars
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Bacterial types that need enriched media:
Haemophilus and Neisseria
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Neisseriand Haemophilus need what type of media?
enriched
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What does Enriched media supply advantagously?
Vitamins, minerals, cofactors
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Which type of media provides vitamins, co factors and minerals?
Enriched media
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Selective media is used for:
selection of certain organsims and inhibition of others
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selective agenst usde in media include:
dyes, antibiotics and salts
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Selective media is most useful when:
Normal flora need to be inhibited
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Examples of Selective media are:
MacConkey, CNA, Mannitol Salt
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MacConkey, CNA and Mannitol Salt are all exmaples of what type of media?
Selctive media
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MacConkey is made iwth what dye?
crystal violet
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CNA contains what selective agents?
colistin and nalidixic acid
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Mannitol Salt contains what selective agent?
Sodium chloride
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Differential Media is used to:
make different organisms look different
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Differential gaent used are:
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Differential media is useful when:
normal flora must be differntiated from pathogens
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Examples of Differential media are:
MacConkey agar and Mannitol Salt agar
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The differential agent of Mannitol Salt agar is:
Mannitol
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The differential agent of MacConkey agar is:
lactose
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Selective-Differential media combines advantages of both for use in:
stol specimens
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Examples of Selective-Differential media are:
MacConkey and Mannitol Salt
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Critical factors are:
- Disease
- Body site
- susptected pathogens
- presense or basence of normal flora
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Incubation considerations are:
- atmosphere
- temperature
- time
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types of Atmosphere for incubation are:
- aerobic
- anaerobic
- increased C02 (5%)
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temperature types for incubation are generally:
- 35-37 degrees Celsius
- 25 degrees Celsius for some fungi sporulation
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Incubation times are generally:
24-48 hours
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Macroscopic morphology includes:
- colony type
- Hemolysis
- Pure or mixed
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Colony type includes:
size, shape, consistency and color
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Hemolysis (on blood agar) can be:
alpha, beta and gamma
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Pure or mixed cultures can be determined by:
visual inspection of differences
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A molar tooth colony look like:
A molar took, surrounded by petals
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Medusa head colonies look like:
hairy
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Swarming proteus colonies look like
Bulls eye/target
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Alpha hemolysis looks like:
Dark greenish agar under colonies (incomplete)
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Beta hemolysis looks like:
Complete hemolysis. The agar appear lightened or yellow under the colonies
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Gamma Hemolysis looks like:
No hemolysis. The agar appears unchanged under the colonies
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Microscopic morphology includes:
- Gram reaction
- Shape
- Arrangement
- Size
- Spore and Capsule
- Acid fast staining
- ALL of a single organism
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Staph looks like
clusters
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pneumococci are arranged in:
pairs
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Acid fast staining positive reactions looks like:
red
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Acid fast stain negative reaction looks like:
blue
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Acid fast staining indicates:
mycobacteria
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Identification of microbe can be performed by:
macroscopic and microscopic evaluation and physiological tests
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Physiological tests are generally of this formula:
enzyme +substrate = product which is then detected.
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Catalase detects what?
H202
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H202 and catalase results in:
bubbles
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Glucose fermentation is usually detected by:
pH indicator (glucose breakdown leads to lowered pH)
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Direct detection of microbes can be carried out by:
- Microscopy
- Tests for antigens
- molecular tests
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Molecular tests include:
probes and PCR
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Tests for antigens require what
specific antibodies to create agglutination reactions
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An example of a test for an antigen is
EIA or enzyme immunoassay
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Enzyme immunoassay is what type of detection method?
Direct detection: test for antigen
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Microscopy includes what tests:
- gram stain
- acid fast stain
- direst flourescent antibody stain (DFA)
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gram stain, acid fast stain and direct flourescent antibody stain are examples of:
Microscopy
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Enzyme immunoassay is carried out by these steps:
- 1.) antibody bounds to solid phase
- 2.) add antigen slution and wash off
- 3.) add specific antibody conjuated to enzyme
- 4.) add substrate
- 5.) view for color reaction
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An example of an Enzyme immunoassay is:
Step A detection
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Molecular probes are:
complements to DNA
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Serology method is direct or indirect?
Indirect method -detect s specifi antibodies to infectous agents
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Serology requires:
antibodies present in a high concentration
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Recent infection can be detected by serological methods if data show:
greater than or equal to 4 fold rise in titer
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Past infection can is edtected via serological methods when:
there is less than a four fold increase in titer
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no present titer means:
no infection
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indications for serological tests:
- inability to diagnose infection directly
- for epidemiologic survey
- determine immune status
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The best indicator for immunity is a:
serological test
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the best indicator of population exposure is what method?
serological tests
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If culture is impossible the most rapid and accurate method of detecting/identifying an infection is:
Serological assay
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convalescent means:
recovering from an infection
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Which type of test can identify both acute and retrospective infections?
serology
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