II. Technique: Obtaining Samples

  1. Dacron Polyester swab of posterior nasopharynx
    1. Insert into posterior nostril
    2. Leave swab in place for 10 seconds
    3. Do not swab anterior nare or throat (low efficacy)
  2. Nasopharyngeal aspirate
    1. Higher efficacy than swab
    2. Requires special equipment

III. Labs: Tests Recommended by CDC (obtain both PCR and culture)

  1. Nasopharyngeal swab PCR
    1. Indicated as first-line test for Pertussis
    2. Test Sensitivity: 94%
    3. Test Specificity: 97%
    4. Result returned in 1-2 days
    5. Pertussis Culture was previously recommended by CDC for confirmation
      1. PCR is now considered accurate enough for diagnosis without confirmatory culture
  2. Pertussis Culture
    1. Previously indicated for confirmation of positive PCR (but PCR alone is now considered sufficient)
    2. Test Specificity: 100%
    3. Test Sensitivity
      1. Overall: 15%
      2. Early disease: 80%
      3. After Erythromycin for 4 days: approaches 0%
    4. Result returned in 7-12 days

IV. Labs: Tests Not recommended by CDC

  1. Pertussis Direct Fluorescent Antibody (DFA)
  2. Pertussis Serology (not standardized)

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