The tuberculosis (TB) bacteria can be resistant to one or multiple used first line medicines. Multidrug Resistant Tuberculosis or MDR-TB, a form of tuberculosis (TB) that is resistant to two of the most potent anti-TB drugs (rifampicin and isoniazid). Sometimes the tuberculosis (TB) bacteria might be resistant to only one anti-TB drug, the most common is resistance to isoniazid.
Children usually acquire MDR-TB through transmission from a family member or close contact with MDR-TB. In some children improper tuberculosis (TB) treatment leads to drug resistant tuberculosis (TB).
Why is it important to know about drug resistance in tuberculosis (TB) treatment?
As per the recent data the incidence of drug resistant tuberculosis is increasing and thought to be approximately 5 to 10% of the total tuberculosis (TB) cases. Children who have drug resistant tuberculosis (TB) would usually not respond to the first line treatment which is started. Knowing to which drug the bacteria is sensitive makes treatment easier and more effective. Since the treatment of multi drug resistant tuberculosis or MDR-TB is completely different compared to drug sensitive tuberculosis (TB) it is extremely important to know whether the bacteria is sensitive or resistant. In case the child has drug resistant tuberculosis (TB) but gets treatment for drug sensitivity the child will not improve. On the other hand the disease would progress and lead to more problems. In addition the child or the adult who has drug resistant tuberculosis and is inappropriately treated would spread the bacteria to the other family contacts during this time.
When should you suspect drug resistant TB?
The current national guidelines is to test all patients including children with tuberculosis (TB) for at least resistance to rifampicin, which is the key drug for treatment of tuberculosis (TB). In case resistance has not been checked at the start of treatment, any child who fails to improve after one month of tuberculosis (TB) treatment should be evaluated for drug resistance. In addition any child who is detected to have tuberculosis (TB) a second time and patients who have stopped treatment of tuberculosis (TB) in between (called as a defaulter), should also be evaluated for drug resistance. Children who have contact at home who have drug resistant tuberculosis (TB) should also be screened for drug resistance before starting treatment for tuberculosis (TB) disease.
Which tests are used to diagnose drug resistant tuberculosis?
The diagnosis of Multidrug Resistant Tuberculosis or MDR-TB can be challenging, especially in young children because of two reasons. First, young children cannot easily produce a sputum sample for bacteriological testing. Second, children have a low number of bacilli in their samples compared to adults, making it difficult for the tuberculosis (TB) tests to detect the bacteria.
In older children a sputum sample is sent for analysis to the laboratory. In children who are young and are unable to bring out sputum either a gastric aspirate or an induced sputum can be performed. In some situations if the sample is not adequate, a bronchoscopy and bronchoalveolar lavage needs to be performed. Children who have lymph node tuberculosis a lymph node aspirate can be done. Other samples like tissue biopsies might be required depending on the situation and involvement of tuberculosis (TB) in particular organs.
The samples as mentioned above are sent to the laboratory for detailed analysis. Recently, molecular tests are available which have made the diagnosis of tuberculosis (TB) rapid and more accurate. These tests include Cartridge based nucleic acid amplification test, also known as a Gene Xpert test, Line Probe Assays, also known as Hain’s test and MGIT tuberculosis (TB) cultures.
In case your child is detected to have tuberculosis (TB) all efforts should be made to detect the bacteria and check whether the bacteria is sensitive to the commonly used anti TB medicines. If the child with tuberculosis (TB) doesn't seem to be responding or has been detected to have tuberculosis (TB) a second time or has stopped treatment in between there are very high chances of having drug resistance. You need to get in touch with a child TB specialist for further guidance and treatment.