How Does A Sputum Test for TB Work?
- Tuberculosis (TB) is an infectious bacterial disease that usually attacks the lungs. It is spread through the air by coughing, sneezing, even speaking. Symptoms of TB include a severe cough that lasts for more than three weeks; chest pain; coughing up blood or bloody sputum; weakness; loss of appetite and weight loss; chills; fever and night sweats. TB can also be latent--it may be present in a person but not cause any symptoms. Latent TB carriers do not spread the disease. A sputum (phlegm) test can be used to detect TB infections of either type.
- Sputum is material coughed up from the lungs. To perform a sputum test, the patient coughs deeply to expel sputum into a sterile cup. The sputum is then analyzed in a laboratory. The lab technician smears a sample of the sputum on a microscope slide and then stains it with a special stain that causes TB bacteria to show up under fluorescent light. This will indicate the presence or absence of TB in the sputum sample.
- The sputum test also provides a method for further treatment of infected individuals. The bacteria that cause TB have evolved into many forms and have different responses to different types of medications. The bacteria in the sputum sample can be cultured (multiplied) so that different types of antibiotics and drugs can be tested on that particular strain of bacteria to determine the best course of treatment.
Children or patients with respiratory problems may not be able to produce sputum. Sputum can still be sampled using a bronchoscope or by trying to isolate the bacteria from other locations in the body.
