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.
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 gently tap 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 this time.
Your child may experience 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.
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 identified under a microscope or through chemical tests. If the tests indicate an infection, an additional 1-2 days may be required to determine which antibiotic is best suited to treat it.
Coughing to produce the sputum specimen may be mildly uncomfortable, but there are no risks associated with this procedure.
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 about the sputum respiratory screen, speak with your doctor.
Reviewed by: Yamini Durani, MD
Date reviewed: June 2012
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