Drug Resistant Tuberculosis Mumbai Cases under Investigation

The Union Ministry of Health and Family Welfare has sent a central team of doctors to Mumbai to ascertain facts about the reported cases of Drug Resistant Tuberculosis cases. The central team comprising of Sr. Chief Medical Officer, Central TB Division (CTD), GOI; Consultant (Drug Resistant TB), CTD and National Program Officer (Lab.), WHO-India has already reached Mumbai on 16th January 2012 and started situation analysis. The team is in touch with the health authorities of Maharashtra, Mumbai Corporation, while also involving experts from concerned stake holders including Hinduja Hospital, Mumbai.

So far as report from Hinduja Hospital is concerned, this Hospital Laboratory is not accredited by the Revised National Tuberculosis Control Programme, GOI for culture and sensitivity for second line drugs to diagnose Extensively Drug-Resistant (XDR) / Totally Drug Resistant (TDR) cases and is only accredited for conducting Drug Susceptibility Testing (DST) by liquid culture and sensitivity for first line drug only. Recently, a proposal for accreditation of Line Probe Assay test (LPA) has been received and is under process.

As of now, the Revised National TB Control Programme has accredited only following three labs for conducting quality-assured second-line anti-TB drug susceptibility testing of flouroquinolones and injectables, viz (1) National TB Institute (NTI), Bangalore; (2) LRS Institute of TB and Chest Disease, New Delhi, and (3) National Institute of Research in Tuberculosis, Chennai.

In addition, the term TDR ‘totally drug resistant’ TB is non-standardized and is misleading; testing for resistance beyond XDR-TB is not advocated by WHO and poor clinical response to treatment has not yet been correlated with diagnosis of drug resistant TB without Laboratory conformation from Accredited Labs.

Multi-Drug Resistant (MDR-TB) is defined as resistance to at least isoniazid and rifampicin (two of the most potent first line anti-TB drugs), with or without resistance to other first-line drugs; Extensively Drug-Resistant TB (XDR-TB) is defined as resistance to at least Rifampicin, Isoniazid (i.e. MDR-TB) plus resistance to any fluoroquinolone, and to any of the 3 second-line injectable drugs (capreomycin, kanamycin and amikacin).

The term “totally drug resistant” tuberculosis is neither recognized by the WHO nor by Revised National Tuberculosis Control Programme (RNTCP). For now these cases are defined as Extensively Drug Resistant tuberculosis (XDR-TB), according to WHO definitions, and accordingly can be managed by national XDR-TB treatment guidelines. Current WHO recommendations advise against the use of the Drug Susceptibility Testing (DST) results for second line drugs beyond those used to identify XDR-TB to guide treatment.

Any type of Drug Resistant TB can only be diagnosed by Laboratory Test and not by clinical examination alone. Preliminary results of second-line DST for MDR-TB patients from DOTS Plus sites and also isolates collected from Gujarat and Maharashtra drug resistance surveys show that there is not yet any XDR-TB amongst new cases and ~0.5% amongst re-treatment cases.