Drug Resistance Tuberculosis

Tuberculosis drug resistance is a man-made amplification of spontaneous mutations in the genes of tuberculosis bacilli. Anti-tuberculosis (TB) drug resistance is a major public health problem. It threatens the progress made in TB control and care Worldwide. Drug-resistant TB occurs when the drugs used to treat TB are misused or mismanaged in drug-susceptible TB patients.  The administration of improper treatment regimens, issues of drug compliance are the few actions that lies beneath the improper use of TB drugs. The drug resistance arises in region/places where TB control programmes are weaker.

Multidrug-resistant tuberculosis (MDR Tuberculosis) refers to resistance to two or more anti-tuberculosis drugs. The two most potent TB drugs isoniazid and rifampin are used to treat all persons with TB disease.  When sputum smear positive/active tuberculosis is treated with a single drug “acquired drug resistance” may be produced. The growth of susceptible strains to that drug is suppressed, but the multiplication of drug-resistant strains is permitted. Acquired drug resistance may be caused by irregular drug supply, inappropriate prescription, or poor adherence to treatment. Primary resistance may occur when a person is infected for the first time with a drug-resistant strain of tuberculosis from someone who harbors MDR tuberculosis and may not be receiving adequate treatment. WHO estimates that every year 490,000 MDR tuberculosis cases emerge, with more than 110,000 deaths. Surveillance data shows that several countries with the highest burden of tuberculosis have significant multidrug resistance tuberculosis. 

 

Extensively drug-resistant TB (XDR TB) is a rare type of MDR TB. XDR TB is resistant to isoniazid and rifampin, plus any fluoroquinolone and at least one of three injectable second-line drugs.  XDR TB is resistant to the most potent TB drugs therefore; patients are left with much less effective treatment options. People with HIV infection and weaker immune system are more likely to develop TB disease once they are infected, and also have a higher risk of death once they develop TB. XDR TB is of special concern for people with HIV infection or other conditions that can weaken the immune system. The latest report of highly lethal strains of XDR tuberculosis underscores the potential threat of expanding resistance. XDR tuberculosis has been found in 45 countries; at least one case has been confirmed in these countries.  The highest rates of MDR tuberculosis are in countries of the former Soviet Union and China.  In the two countries with the highest tuberculosis burden, China and India, 8% and 5% of tuberculosis cases are estimated to have MDR tuberculosis. Drug-resistant tuberculosis in global "hot spots” has already reached a level at which the relatively inexpensive DOTS approach is not adequate to address the tuberculosis problem.

DOTS remain the most important intervention for preventing MDR tuberculosis. DOTS treat regular tuberculosis if, administered properly. It also prevents the development of drug-resistant tuberculosis. If drug-resistant tuberculosis is already present among a population programmatic management of MDR and XDR tuberculosis strategy should be considered. The DOTS and programmatic management of MDR and XDR tuberculosis needs to be an integrated approach. The most important way to prevent the spread of drug-resistant TB is by focusing on the issue of compliance. It is very crucial for the patient to understand that prescribed TB drugs should be taken regularly as directed. The prescribed doses should not be missed and treatment should not be stopped prematurely. Better counseling techniques needs to be in place, so that during patient follow-up the issues related to non-compliance should be diagnosed and addressed.  Another way to prevent drug-resistant TB is by avoiding exposure to known drug-resistant TB patients in closed or crowded places such as hospitals, prisons, or homeless shelters.