Kids with cystic fibrosis (CF)
tend to get frequent respiratory infections, sometimes caused by bacteria
or fungi. A sputum (mucus) CF respiratory screen or culture helps doctors detect
and identify these bacteria or fungi so they can prescribe the most effective antibiotics
to target a specific infection.
Why It's Done
A sputum culture can help identify specific causes of infections in the lungs and
airways. Such infections can lead to coughing that produces yellow, greenish, or blood-tinged
sputum, in addition to fever and difficulty breathing.
Before the test, be sure to tell the doctor whether your child has taken antibiotics
recently. The best time for testing is usually in the morning, before your child has
had anything to eat or drink. Also, make sure your child doesn't use mouthwash before
the test because it may contain antibacterial ingredients that could affect results.
Your child will be asked to rinse his or her mouth out with water, then breathe
deeply and cough deeply to produce sputum from the airway.
You or the health professional helping your child may need to tap gently on your
child's chest to loosen the sputum in the lungs. If your child can't produce a sample,
the lab technician may need to use a tongue depressor to stimulate a cough, or your
child may need to inhale a mist solution to help produce a cough.
If your child is scheduled for a bronchoscopy (a test done with a small telescope
to evaluate the upper airway and bronchi), a sputum screen is likely to be done at
What to Expect
Your child may feel mild discomfort when taking a deep breath or coughing. If your
child inhales the mist solution, the urge to cough may be strong. It may take several
attempts at coughing to produce the amount of sputum needed for the test.
Getting the Results
The sputum sample is collected into a sterile container and sent to a laboratory.
The sample is then placed on a special plate that enables growth of certain bacteria
and fungi if an infection is present.
If your child has a bacterial infection, the organisms may need 48 hours to grow.
Fungi need a week or longer. These organisms will be seen under a microscope or through
chemical tests. If the tests show an infection, another 1-2 days may be needed to
choose the best antibiotic to treat it.
Coughing to produce the sputum specimen may be mildly uncomfortable, but there
are no risks associated with this procedure.
Helping Your Child
Explaining the test in terms your child can understand might help ease any fear.
Also reassure your child that the procedure doesn't hurt.
If You Have Questions
If you have questions about the sputum respiratory screen, speak with your doctor.