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MDR in India & abroad |
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Although drug resistance in tuberculosis in India has been reported frequently during the last four decades, the available information from India is localized, inaccurate or incomplete. In order to formulate a national treatment policy, reliable and periodic updates on the prevalence of drug resistance for the entire country is needed, which would serve as an indication of the transmission of drug resistant organisms as well as the efficacy of the NTP. In view of the large size of the country and several other administrative as well as financial constraints, surveys of drug resistance at a national level are logistically difficult to undertake. Most of the published reports on drug resistance in India, with the exception of studies reported from the Tuberculosis Research Centre (TRC) in INDIAN J MED RES, OCTOBER 2004 ,Chennai, the National Tuberculosis Institute (NIT) in Bangalore and a few others, are deficient in several aspects, such as lack of standardized methodology, improper elicitation of previous treatment history, sample selection, non-uniformity in bacteriological procedures, sub-standard drug powders used for susceptibility testing and lack of quality assurance studies. In India , drug resistance patterns vary widely across different parts of the country. The data on drug resistance in ‘new’ cases has been variously estimated by different investigators. The first nation wide survey conducted by Indian Council of Medical Research (ICMR) during the 1960s showed a resistance level of 8.2% to Isoniazid (H) alone, 5.8% to Streptomycin (S) alone, and 6.5% to both the drugs (SH). Data published by the Tuberculosis Research Centre (TRC), Chennai have shown a gradual rise in the prevalence of resistance in ‘new’ cases over the past four decades, 3% to 17% for Isoniazid and 3% to 13% for Streptomycin. Drug resistance to Rifampicin emerged during the 1990s and data from the recent studies conducted by TRC and NTI, have reported MDR-TB levels between 0.5% to 3% in new cases and 12% amongst re-treatment cases. A high prevalence of MDR-TB is mostly due to poor TB case management. Any intervention designed to treat and /or control MDR TB must place the highest priority on correcting such errors in TB management, in the public as well as the private sector, prior to incorporating treatment for MDR-TB cases into the programme. The current global concern in the treatment of tuberculosis (TB) is the emergence of resistance to the two most potent drugs viz., Isoniazid and Rifampicin. The level of initial drug resistance is an epidemiological indicator to assess the success of the TB control programme. Though drug resistance in TB has frequently been reported from India , most of the available information is localized, sketchy or incomplete. A review of the few authentic reports indicates that there is no clear evidence of an increase in the prevalence of initial resistance over the years. However, a much higher prevalence of acquired resistance has been reported from several regions, though based on smaller numbers of patients. A strong TB control programme and continuous surveillance studies employing standardized methodology and rigorous quality control measures will serve as useful parameters in the evaluation of current treatment policies as well as the management of multidrug resistant (MDR) TB cases. Despite all the advances made in the treatment accelerated this situation and it is believed that, as of and management, tuberculosis (TB) still remains as now, about 3.5 million people in India are infected one of the main public health problems, particularly with HIV2. There is a grave concern in India regarding in the developing countries. India accounts for nearly the increase in HIV-associated TB and the emergence 30 per cent of the global TB burden1. of MDR-TB in both magnitude and severity of TB epidemic. Causes of drug resistance The emergence of drug resistance in M. tuberculosis in India has been associated with a variety of management, health provider and patient-related factors. These include
Initial drug resistance in India The Indian Council of Medical Research (ICMR) undertook drug resistance studies during 1965-67 in nine urban areas of the country. However, this exercise was not a surveillance study and did not use strict sampling techniques, the centres being selected more for logistic considerations than for epidemiological reasons. Sputum specimens collected from all patients attending chest clinics were tested for drug susceptibility to streptomycin, Isoniazid, Para amino salicyctic acid (PAS) and thioacetazone. The first study was on patients who had denied any history of previous treatment, while in the second study, patients with and without previous chemotherapy were included. The results showed that in the first study resistance to Isoniazid ranged from 11-20 per cent, to streptomycin from 8-20 per cent and to both drugs from 4-11 per cent. The second study showed resistance to Isoniazid to range from 15-69 per cent, to streptomycin from 12-63 per cent and to both drugs from 5-58 per cent. Further, the level of drug resistance was proportional to the duration of previous treatment. A decade later, a study at the Government Chest Institute and Chest Clinic of Government Stanley Hospital (GCI-SH), Chennai20 yielded results similar to those in earlier ICMR surveys, indicating that the prevalence of initial drug resistance had not risen during the span of ten years. However, both the above studies were undertaken in the pre-Rifampicin era and are not of relevance in the present setting. During the 1980s, though the levels of initial drug resistance to Isoniazid and streptomycin in 11 reports (Table II) were similar to those in the earlier studies, Rifampicin resistance was observed in all the centres studied except Gujarat . The rates of acquired resistance are invariably higher than those of initial resistance, though data on acquired resistance are limited. A study conducted by the Institute of Thoracic Medicine , Chennai in four District Tuberculosis Centres of Tamil Nadu, showed that acquired resistance was 63 per cent, out of which 23.5 per cent was resistance to single drug and 39.5 per cent to more than one drug. Resistance to Isoniazid and Rifampicin (MDR-TB) was reported in 20.3 per cent. TB in all the centres (except Wardha) was observed to be less than 5 per cent. The reason for the emergence of Rifampicin resistance during this period may be the introduction of short course chemotherapy (SCC) regimens containing Rifampicin. Further, a higher level of initial drug resistance to Isoniazid (32.9%) was observed among the rural population in Kolar compared to the urban patients, contradicting a Korean study, where a much higher level of initial resistance was seen among urban patients, attributed to easy access to the Antituberculosis drugs. There was also an increase in the proportion of initial drug resistance to Rifampicin (4.4%) encountered in this rural population in Karnataka. In the early 1990s, a retrospective study done at New Delhi showed a high level of initial drug resistance to Isoniazid (18.5%) and a low level of resistance to Rifampicin. In view of the results presented above, there is no clear evidence of an increase in the prevalence of initial drug resistance in India over the years. However, relatively high prevalence of acquired resistance has been reported from Gujarat , New Delhi , Raichur and North Arcot districts. When compared to the global prevalence of drug resistance, initial drug resistance is found to be marginally less while that of acquired resistance is much higher in India in specialized settings. The magnitude of drug resistance problem to a large extent is due to acquired resistance. The prevalence of MDR-TB also is found to be at a low level in most of the regions of India . However, these studies need to be repeated in different regions and in diverse settings to reconfirm this belief. TRC, Chennai and NTI, Bangalore have been working closely with central TB division and finalized recently a protocol for carrying out drug resistance surveillance (DRS) at the state level. The central TB division has been providing assistance to investigators in carrying out DRS at their respective places. As a follow-up, DRS protocols have been finalized for two large Indian states, namely, Gujarat and Maharashtha and the results are expected to be known in 2005. Similar efforts are underway for two other states, namely, Andhra Pradesh and Orissa with funds provided by the WHO Global Fund for AIDS, tuberculosis and malaria (GFATM). MDR TB abroad Links: 1.
International Union
Against Tuberculosis
and Lung Disease 4.
Amedeo - The Medical Literature Guide References 1.
PROBLEMS IN ESTIMATING THE BURDEN OF PULMONARY TUBERCULOSIS IN
INDIA: A REVIEW Review Article |
