TDR TB: ARE WE PREPARED

“The health is not all, but all without the health are no one.” Socrates. 

Totally drug resistant; Are we prepared for this?

Tuberculosis is one of the most serious infectious diseases of the developing world and it remains the leading cause of death from infectious disease globally. Tuberculosis (TB) is a contagious and potentially fatal disease that can affect almost any part of the body but manifests mainly as an infection of the lungs. It is caused by a bacterial microorganism, the tubercle bacillus or Mycobacterium.

 Totally drug-resistant tuberculosis (TDR-TB) is a generic term for tuberculosis strains that are resistant to a wider range of drugs than strains classified as extensively drug-resistant tuberculosis. TDR-TB has been identified in three countries; India, Iran, and Italy. The emergence of TDR-TB has been documented in four major publications. TDR-TB has resulted from further mutations within the bacterial genome to confer resistance, beyond those seen in XDR- and MDR-TB. Development of resistance is associated with poor management of cases. Drug resistance testing occurs in only 5% of TB cases worldwide. Without testing to determine drug resistance profiles, MDR- or XDR-TB patients may develop resistance to additional drugs. TDR-TB is relatively poorly documented, as many countries do not test patient samples against a broad enough range of drugs to diagnose such a comprehensive array of resistance. The United Nations' Special Programme for Research and Training in Tropical Diseases has set up a TDR Tuberculosis Specimen Bank to archive specimens of TDR-TB. Multi-drug-resistant tuberculosis (MDR-TB) is defined as tuberculosis that is resistant at least to isoniazid (INH) and rifampicin (RMP), the two most powerful first-line anti-TB drugs. Isolates that have multiple resistant to any other combination of anti-TB drugs but not to INH and RMP are not classed as MDR-TB. Extensively drug-resistant tuberculosis (XDR-TB) is a form of tuberculosis caused by bacteria that are resistant to some of the most effective anti-TB drugs. XDR-TB strains have arisen after the mismanagement of individuals with multidrug-resistant TB (MDR-TB).

Though terms likes such as “totally drug resistant” have not been clearly defined for tuberculosis by WHO. While the concept of “total drug resistance” is easily understood in general terms, in practice, in vitro drug susceptibility testing (DST) is technically challenging and limitations on the use of results remain: conventional DST for the drugs that define MDR and XDR-TB has been thoroughly studied and consensus reached on appropriate methods, critical drug concentrations that define resistance, and reliability and reproducibility of testing. Data on the reproducibility and reliability of DST for the remaining SLDs are either much more limited or have not been established, or the methodology for testing does not exist. 

To be remembered is the fact that the race by all medical practitioners to find a cure started since the existence of TB down to all its variants. Yet this mycobacterium seems to elude us as it keeps resisting each of our solution? Hence, it begs the question will these devastating disease take its leave? Will it be eradicated completely? Will our generation survive it? And if yes, will another strain of this mycobacterium exist?

Finally, I ask you all if our medical society of practitioners will survive these.