Clinical diagnostic techniques

• What is the first clinical diagnostic technique mentioned for isolating microorganisms?

  Isolation of microorganisms by colonization and culture
• What technique is used for the identification of specific microbial genes or products?

  PCR and MALDI-TOF-MS
• What is the third clinical diagnostic technique mentioned?

  Detection of specific antigen of antibody to a pathogen
• What is the purpose of counter stains in clinical diagnostics?

  Counter stains are used to enhance the visibility of microorganisms.
• What factors contribute to the quality of samples collected for clinical diagnostics?

  Good quality samples depend on optimal timing, appropriate samples, minimal contamination, and minimal delay to the lab.
• What are the steps involved in the isolation and culture of microorganisms?

  1. Microscopy - cell morphology and staining
  2. Culture - isolation of pure sample using streak plates and differential/selective media
  3. Identification - biochemical assays
  4. Sensitivity testing - MIC and disc test
• What is the purpose of staining techniques in microscopy?

  Staining techniques provide rapid indication of the type of microorganism.
• What color indicates a Gram-positive bacterium after Gram staining?

  Purple (crystal violet)
• What color indicates a Gram-negative bacterium after Gram staining?

  Pink (counter stain)
• What is the significance of the Ziehl Neelsen stain?

  It confirms bacterial infection and is rapid and inexpensive.
• What is the purpose of streak plates in microbiology?

  Streak plates are used to produce single colonies from a mixed culture.
• What is the disc diffusion method used for?

  It is used to measure the zone of inhibition to determine bacterial sensitivity to antimicrobials.
• What does MIC stand for in microbiology?

  Minimum inhibitory concentration
• What is the breakpoint in antimicrobial susceptibility testing?

  Breakpoint is the highest plasma concentration of a drug that can be safely achieved in a patient.
• What are the advantages and disadvantages of biochemical identification methods?

  Advantages:

  • Culturable cells
  • Entered whole species
  • Culture sensitivity for resistance
  • Cost-effective

  
  

  Disadvantages:

  • Lengthy process (days or more)
  • Potential for errors
  • Anaerobic conditions must start before completion
• What is the basic principle of PCR?

  PCR involves repeated cycles of heating and cooling to copy a specific piece of DNA.
• What is used as a template in PCR?

  Pathogen DNA extracted from the sample
• At what temperature does the denaturation step of PCR occur?

  96°C
• What happens during the annealing step of PCR?

  Specific DNA primers attach to the target DNA at 60°C.
• What occurs during the extension step of PCR?

  DNA polymerase adds single nucleotides to the primer to create identical DNA.
• What is the purpose of quantitative PCR (qPCR)?

  qPCR allows measurement of DNA generation during each cycle of PCR.
• What is one advantage of using PCR in clinical diagnostics?

  PCR is faster than culture and can detect viruses and resistance genes directly from samples.
• What are the steps involved in the MALDI-TOF-MS process?

  1. Sample co-crystallized with matrix on target
  2. Ionized by MALDI using a nitrogen/UV laser
  3. Charged molecules accelerated by electric field
  4. Ions separated by mass-to-charge ratio (m/z)
  5. Mass spectra produced for analysis
• What is one advantage of using MALDI-TOF-MS in diagnostics?

  MALDI-TOF-MS provides very rapid results (30 minutes) and is highly accurate.
• What do immunoassays detect in clinical diagnostics?

  Viral/bacterial antigens and antibodies
• How does the enzyme-linked immunosorbent assay (ELISA) work?

  ELISA uses antibodies to capture specific target antigens from a sample.
• What is a key advantage of lateral flow immunoassays?

  Lateral flow immunoassays are fast and do not require specialized equipment.