What is Culture-Sputum?
Sputum is usually brought up from the lungs and may contain mucus, saliva, and cellular material. A sputum culture is a laboratory test that is done to identify infections in the lungs and airways by placing bacteria, viruses, or fungi from the sputum sample which is obtained from the respiratory tract.
This test is used in the diagnosis of various respiratory conditions including pneumonia, tuberculosis, and bronchitis by determining the causative pathogen. When the culture is done in the lab, the doctor can tell which bacteria, virus or fungus is present and which antibiotic or antifungal can be used to treat the infection.
How is the Test Performed?
The sputum culture test is not invasive and is collected in the morning as the mucus is thick and ensures accurate results.
Preparation
- Do not use a mouthwash before the test
- Drink more water the night before the test
- Avoid eating for at least 1 to 2 hours before the test
Collection
- The patient is asked to cough deeply from the lungs to collect the sputum sample in a sterile container
- The sample is then sent to the laboratory for further analysis
Lab Analysis
- The sample is then placed on the culture medium to allow the growth of the microbes.
- The culture is incubated for several days to get the maximum growth.
What are the symptoms that prompt this test?
The healthcare provider suggests this test when the patient is exhibiting the symptoms of respiratory tract infection;
General Symptoms
- Sputum production in excessive amounts due to cough
- Fever
- Chills
- Shortness of breath
- Coughing or breathing resulting in chest pain
- Onset of confusion in elderly
What are Normal Ranges for This Test?
The normal results are an indication of no presence of the pathogenic bacteria in the culture. The results indicate the presence or absence of the pathogenic bacteria.
Negative – Absence of pathogenic bacteria
Positive –Presence of pathogenic bacteria such as Streptococcus pneumoniae, Mycobacterium tuberculosis, or Haemophilus influenzae
**When the test results are positive the healthcare provider suggests a follow-up test of antimicrobial sensitivity to initiate an effective treatment.**
What Happens if Test Results Show Abnormal Levels?
Various pathogens can cause several infections and disorders in an individual. The following conditions are usually diagnosed in patients who have shown a positive sputum culture result;
- Pneumonia
- Bronchitis
- Tuberculosis
- Cystic fibrosis
- Fungal infections in the respiratory system
- Valley fever
- Seasonal flu
- COVID-19
- Lower respiratory tract infection
The healthcare provider will suggest the most appropriate treatment course involving antibiotics, antifungal medication, and antiviral drugs according to the type of the pathogen causing infection.
Additional testing is also recommended in some cases such as chest X-ray, TB skin test, sputum smear molecular test, or other tests.
