M2 Flashcards
what is the procedure of sampling as part of a clinical practice/ research?
- handling of specimen
- laboratory processing and reporting
- interpretation and use of information
Describe isolating and identifying organism.
- Sample- (for culture,microbial product detection, Ab detection)
- Timing- (secondary infection)
- Handling- ( rapid/match transport medium)
- Request form- (relevant clinical information,thorough and concise)
How do you sample purulent infection?
- aspirate of pus
- prevents contamination
- maintains anaerobes
How do you sample mucosal infections?
- yeast,swab or oral wash
- herpes,lesion swab
how long after are results received for sample cultures?
within 2-5 days
Describe the process of samples for culture.
-Streaked on Blood Agar, aerobic & anaerobic
– Smear of pus fixed and analysed by Gram stain
– Initial plate seeded for Antibiotic sensitivity
– Visible colonies analysed at 24-48 hours
– Biochemical profiling
– Antibiotic sensitivity determined (24-48 hours)
– Prolonged incubation for slow growing species optional
what are the reasons for culturing?
- determines viability (aerobic versus anaerobic)
- component species (mixture of species
- provides pure materials (amplifies the bacteria/fungus responsible, choose single colony for further characterisation)
what is the primary inoculum?
clean loop to spread bacteria
what is general media?
transport media :
-excess of nutrients
what is enrichment media?
addition of blood/serum/extracts will support growth of fastidious organisms
what is selective media?
- a media that selects for the growth of specific prokaryotes
- presence of specific substances permits the growth of one organism over another
what is differential media?
Incorporation of chemicals produces visible changes in colonies that facilitate identification
How are colonies identified?
Microscopy (single colony or pus sample):
– Pure culture or polymorph
– Shape, size, grouping
– Structures (capsules, flagella, spores)
– Staining (Gram)
what is the shape of cocci?
spheres
what are the arrangements of cocci?
- single coccus
- pair of cocci (diplococci)
- cluster of cocci (staphylococci)
- chains of cocci (streptococci)
what is the difference between staphylococci and streptococci?
staphylococci changes direction and forms cluster whereas streptococci growths in one direction to form poles
Describe the process spores and involved in.
- binary fission
- sporulation
- prespore
- endospore
- cell lysis
- spore
- germination
Describe biochemical characterisation.
Metabolic profiling:
- utilisation of carbon sources
- utilisation of amino acids
Describe serological tests.
Host immune response to Ag by the raising of
Abs.
• Ab specific to microbe/virus (polyclonal), or
single component (monoclonal)
• Detect presence of specific IgM Ab to virus/ microbe
• Demonstrate in vitro by agglutination (aggregation) reaction
• Rapid detection of viruses (24 hours), even possible to identify the stage of infection using two different tests.
• Can identify specific Serotypes of bacteria
Name 3 immunological techniques.
- agglutination reactions (clumping)
- direct fluorescence antibody test (DFA)
- ELISA
what does agglutination do?
slide agglutination use Ag/Ab specificity
what is 16sRNA?
RNA component of Holoenzyme used as molecular signature
molecular signature of bacteria that allows us to assign them to a general species
what does MALDI-TOF do?
-Generates a series of ions from a sample dependent on its constituents
• Separates the ions according to mass & charge
• Detects the spectrum of proteins released from a sample
• Results in characteristic signature
what is effective about MALDI-TOF?
- powerful-99% correct
- rapid- colony tested in 6 mins
- precise
- cost-effective
