AFB Culture, AFB Smear

This is a test on your sputum. Sputum is phlegm, thick mucus that is coughed up from the lungs. The tests are done to look for tuberculosis. Tuberculosis is a disease that is caused by a germ (acid fast bacilli, or mycobacteria) that often affects the lungs. It may be done if you have a long standing cough, weight loss, fever, chills, and weakness that may be due to a tuberculosis infection. Those who do have active TB may not feel ill at first. Early symptoms may be subtle and, if the TB is extra-pulmonary (outside of the lungs in organs such as the kidney and bone), the tuberculosis may be fairly advanced by the time it is causing noticeable symptoms.

These tests are also be used to monitor treatment. TB spreads through the air in secretions from your lungs. It is a public health risk. It is easily spread in confined populations. The very young, elderly, or people withy poor immune systems tend to be vulnerable. AFB smears and cultures can help track and minimize the spread of TB in these populations. The AFB smears are done when a smear of sputum is looked at under the microscope and a specialist looks for the germs which cause TB.


No preparation is required. Usually, three sputum samples are collected early in the morning on different days. Your caregiver will instruct you if there are other special instructions to collect the sputum. Sometimes blood samples are taken if your caregiver suspects infection elsewhere in the body.


No bacilli seen.

Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.


Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.


It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.