Routine sputum culture

Routine Sputum Culture

A routine sputum culture is a test laboratories use to identify bacteria or fungi in a patient's sputum sample. The test can help diagnose infections in the lungs or airways that can lead to respiratory problems, such as pneumonia, bronchitis, and tuberculosis.


To prepare for a sputum culture, the patient should avoid eating, drinking, or brushing their teeth for at least one hour prior to the test. Doctors may also prescribe antibiotics prior to the test to make sure existing infections are treated before the sample is taken.


The procedure for the sputum culture is simple. The patient will be asked to collect an early morning sample into a sterile container. They will then place the sample in the laboratory for testing. The technician will use a sterile swab to take multiple samples from the sputum. The laboratory will then analyze the sample using different techniques to identify bacteria or fungi in it.


There are two main types of routine sputum cultures: wet mount prep and Gram stain. The wet mount prep is used to assess the presence, shape, color, and movement of any microbes that are cultured. In the Gram stain, the sample is stained with a dye to differentiate between different types of bacteria.


The procedure for the sputum culture is generally considered to be risk-free. In rare cases, patients may experience chest pain, coughing up blood, or fever after the test.

Why and When

Doctors may recommend a routine sputum culture to diagnose or monitor an existing infection. For example, if a person is showing symptoms of pneumonia or tuberculosis, their doctor may order a sputum culture to confirm the diagnosis. The test can also be used to check for the presence of drug-resistant bacteria or to identify the cause of frequent respiratory infections. Sputum cultures should not be done in pregnant women, as they are associated with an increased risk of miscarriage.