Why is a sputum culture used after tuberculosis bacteria are found in a sample?

When tuberculosis bacteria are detected in a sputum smear, a sputum culture is performed to confirm that the identified bacilli are specifically Mycobacterium tuberculosis rather than other types of bacteria.1

This diagnostic step is essential because accurate identification of the causative organism ensures that the patient receives the correct antimicrobial drugs for treatment. Furthermore, culturing the bacteria allows clinicians to determine the specific drug sensitivity of the strain, which is critical for managing and preventing the development of multidrug-resistant tuberculosis (MDR TB) and other resistant forms of the disease.2