MLAB%202434%20

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MLAB 2434 CLINICAL MICROBIOLOGYSUMMER,
2005CECILE SANDERS KERI BROPHY

• Chapter 8 Microscopic Examination of Infected
  Materials

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Chapter 8 - Microscopic Examination of Infected
Materials (contd)

• Purposes for direct gram stain from patient
  specimens
• Confirm that specimen submitted is representative
  (ex. Sputum vs. spit)
• Determine probability of infection by identifying
  debris of inflammation
• Identify specific infectious agents

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Chapter 8 - Microscopic Examination of Infected
Materials (contd)

• Guide initial antibiotic therapy
• Use for epidemiologic data
• Direct gram stains observed with light microscope
  after staining
• Preparing smears
• Using swabs
• Smears should not be made using swab that has
  been used to streak cultures

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Chapter 8 - Microscopic Examination of Infected
Materials (contd)

• Ideally, if culture AND gram stain are to be
  done, two swabs of the specimen should be
  collected and sent to the lab
• Swab is NOT rubbed on the slide, but rolled back
  and forth (p. 263)
• Smears from thick liquids or semisolids (ex
  stool)
• Smears from thick or mucoid material
• Pull slides

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Chapter 8 - Microscopic Examination of Infected
Materials (contd)

• Smears from thin fluid (ex CSF)
• Mark back of slide with marking pen to show
  location of specimen on the slide for ease in
  finding under microscope
• Cytocentrifuge

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Chapter 8 - Microscopic Examination of Infected
Materials (contd)

• Examination of Prepared and Stained Slides
• If sputum, first evaluate the smear to determine
  if it is REALLY sputum
• Unacceptable 10-20 squamous epithelial
  cells/LPF
• Acceptable 10-25 PMN/LPF
• Evaluate smear first under low power to look for
  background material, such as WBC (pus),
  epithelial cells, etc.
• Search for microorganims

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Chapter 8 - Microscopic Examination of Infected
Materials (contd)

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