Clinical Diagnostic Techniques

List some of the main ways in which infection can be diagnosed:

• Microscopy, culture, & sensitivity (M, C, & S)

• Biochemical tests

• PCR

• Sequencing

• MALDI-ToF MS

• ELISA

• Lateral flow

What tests do we use to identify microorganisms by isolation and culture?

• Microscopy, culture, & sensitivity (M, C, & S)

• Biochemical tests

How is microscopy used to identify microorganisms?

• We can look at cell morphology

• We can stain a plate and look at it under a microscope to identify what pathogen it is (examples of stains: gram stain, acid fast stain, capsule stain, endospore stain)

How is cell culture used to identify viruses?

• Viruses are grown in tissue culture cell lines

• Characteristic cell damage can help identify viruses

• Plaque assays counts plaques (areas where infected cells have been destroyed) to estimate the amount of infectious virus is in the sample

What are the limitations of cell culture used to identify viruses?

• Time consuming

• Expensive

• Does not always identify the exact virus or determine the most effective treatment

How is cell culture used to identify bacteria?

• Streak plates isolate single bacterial colonies, allowing follow on tests to identify individual species

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