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Routine Sputum Culture

Definition

Routine sputum culture is a test of secretions from the lungs and bronchi (tubes that carry air to the lung) to look for bacteria that cause infection.

Alternative Names

Sputum culture

How the test is performed

You will cough deeply and spit any sputum into a sterile cup. The sputum is then taken to the laboratory. There, it is placed in a special substance (medium) under conditions that allow the bacteria or fungi to grow.

How to prepare for the test

Drinking a lot of water and other fluids the night before the test may help to get the sample.

How the test will feel

You will need to cough. Sometimes the health care provider will tap on the chest to loosen deep sputum. There may be a steam-like mist to inhale to help you cough up the sample.

Why the test is performed

The culture is done on the sputum to help identify the bacteria that are causing an infection in the lungs or airways (bronchi).

Normal Values

In a normal sputum sample there will be no disease-causing organisms present.

What abnormal results mean

If the sputum sample is abnormal, the results are called "positive." Identifying disease-producing organisms may help diagnose:

  • Bronchitis
  • Lung abscess
  • Pneumonia
  • Tuberculosis

Other conditions under which the test may be performed:

  • Aspiration pneumonia
  • Atypical mycobacterial infection
  • Atypical pneumonia
  • Blastomycosis
  • Bronchiectasis
  • Coccidioidomycosis; acute (primary) pulmonary
  • Coccidioidomycosis; chronic pulmonary
  • Coccidioidomycosis; disseminated
  • Cryptococcosis
  • Disseminated tuberculosis (infectious)
  • Histoplasmosis; acute (primary) pulmonary
  • Histoplasmosis; chronic pulmonary
  • Hospital-acquired pneumonia
  • Mycoplasma pneumonia
  • Plague
  • Pulmonary aspergilloma (mycetoma)
  • Pulmonary aspergillosis; invasive type
  • Pulmonary tuberculosis
  • Viral pneumonia

What the risks are

There are no risks with this method of obtaining a sample.

Special considerations

Sometimes a Gram stain or AFB stain of the sputum done at the same time can help make the diagnosis.

Review Date: 10/15/2009

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Information developed by A.D.A.M., Inc. regarding tests and test results may not directly correspond with information provided by UCSF Medical Center. Please discuss with your doctor any questions or concerns you may have.