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• Polymerase Chain Reaction (PCR)


  Enzymatic DNA amplification
• What you need for PCR

  • Sample (containing target DNA)
  • Primers for specific detection
  • Nucleotides
  • Enzyme
• PCR overview


  1. Denaturation of DNA at 95°C

  2. Annealing of primers at 50-60°C

  3. Extension of primers at 72°C
• If primers fit, there is amplification of target DNA
• If primers do not fit, no amplification product => the DNA (micro-organism) was not in the sample
• For RNA detection we use reverse transcriptase to convert RNA to cDNA
• Advantages of PCR


  • Quick
  • Reliable
  • Sensitive
  • Relatively easy
  • Specific
• Restrictions of PCR


  • Contamination of reagents or lab results in false positive results
  • Failure due to a mistake in the protocol
  • Different materials/parts of the sample can inhibit the PCR process
  • Expensive
• Contamination can lead to false positive results and is a major concern in PCR as it can lead to erroneous results
• Viruses detected by PCR diagnostics

  • HIV
  • SARS
  • H5N1
• Bacteria detected by PCR diagnostics

  • meningococcus
  • legionellosis
• Analysis for resistant genes using PCR

  • MRSA
  • VRE
• E. coli is not a bacterium that can be detected using PCR diagnostics