Nasopharyngeal culture

  • Definition
    • Nasopharyngeal culture is a test that examines a sample of secretions from the uppermost part of the throat, behind the nose, to detect organisms that can cause disease.

  • Alternative Names
    • Culture - nasopharyngeal; Swab for respiratory viruses; Swab for staph carriage

  • How the Test is Performed
    • You will be asked to cough before the test begins and then tilt your head back. A sterile cotton-tipped swab is gently passed through a nostril and into the nasopharynx. This is the part of the pharynx that covers the roof of the mouth. The swab is quickly rotated and removed. The sample is sent to a laboratory. There, it is placed in a special dish (culture). It is then watched to see if bacteria or other disease-causing organisms grow.

  • How to Prepare for the Test
    • No special preparation is needed.

  • How the Test will Feel
    • You may have slight discomfort and may gag.

  • Why the Test is Performed
    • The test identifies viruses and bacteria that cause upper respiratory tract symptoms. These include:

      • Bordetella pertussis
      • Neisseria meningitidis
      • Staphylococcus aureus
      • Methicillin-resistant Staphylococcus aureus
      • Viral infections such as influenza or respiratory syncytial virus

      The culture may be used to help determine which antibiotic is appropriate to treat an infection due to bacteria.

  • Normal Results
    • The presence of organisms commonly found in the nasopharynx is normal.

  • What Abnormal Results Mean
    • The presence of any disease-causing virus, bacteria, or fungus means these organisms may be causing your infection.

      Sometimes, organisms like Staphylococcus aureus can be present without causing disease. This test can help identify resistant strains of this organism (methicillin-resistant Staphylococcus aureus, or MRSA) so that patients can be isolated when necessary.

  • Risks
    • There are no risks with this test.

  • References
    • Murray PR. The clinician and the microbiology laboratory. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 16.