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Year : 2014  |  Volume : 32  |  Issue : 4  |  Page : 430--433

Declining trend of resistance to first-line anti-tubercular drugs in clinical isolates of Mycobacterium tuberculosis in a tertiary care north Indian hospital after implementation of revised national Tuberculosis control programme

A Jain, P Diwakar, U Singh 
 Department of Microbiology, Tuberculosis Laboratory, King George's Medical University, Lucknow, Uttar Pradesh, India

Correspondence Address:
A Jain
Department of Microbiology, Tuberculosis Laboratory, King George«SQ»s Medical University, Lucknow, Uttar Pradesh
India

Abstract

Trends showing drug-resistance pattern are needed to understand direction of tuberculosis (TB) control programme. The drug-resistance pattern in state of Uttar Pradesh, India, is not documented. Here we are reporting the prevalence of multi-drug-resistant (MDR) and drug-resistant TB in previously treated cases of pulmonary tuberculosis following launch of revised national TB control programme (RNTCP) in whole of Uttar Pradesh. Isolates of Mycobacterium tuberculosis, from patients of pulmonary tuberculosis, who were treated with antitubercular drugs for more than 4 weeks, were tested for resistance to first-line drugs; streptomycin (S), Ethambutol (E), Rifampicin (R) and isoniazid (H) over a period of 4 years, 2009-2012. Total 2496 isolates of M. tuberculosis were tested, of which 1139 isolates (45.6%) were pan-sensitive and 370 (14.8%) were pan-resistant. Total 695 isolates (27.8%) were MDR. Maximum resistance was with Isoniazid (n = 1069, 42.8%) followed by streptomycin (n = 840, 33.7%), rifampicin (n = 742, 29.7%), and ethambutol (n = 613, 24.6%). A decline in number of MDR strains and individual drug resistance was seen. Total MDR strains in the year 2009, 2010, 2011 and 2012 were 35.6%, 30.8%, 26.7% and 22.8% respectively. The drug resistance pattern reported from time to time may vary substantially. The decline in drug resistance visible over last four years, after implementation of DOTS, appears promising.

How to cite this article:
Jain A, Diwakar P, Singh U. Declining trend of resistance to first-line anti-tubercular drugs in clinical isolates of Mycobacterium tuberculosis in a tertiary care north Indian hospital after implementation of revised national Tuberculosis control programme .Indian J Med Microbiol 2014;32:430-433

How to cite this URL:
Jain A, Diwakar P, Singh U. Declining trend of resistance to first-line anti-tubercular drugs in clinical isolates of Mycobacterium tuberculosis in a tertiary care north Indian hospital after implementation of revised national Tuberculosis control programme . Indian J Med Microbiol [serial online] 2014 [cited 2019 Dec 6 ];32:430-433
Available from: http://www.ijmm.org/text.asp?2014/32/4/430/142257

Full Text

 Introduction



There has been major progress in reducing tuberculosis (TB) cases past two decades. Mortality and incidence rates are falling in all of World Health Organization's (WHO) six regions and in most of the 22 high-burden countries that account for over 80% of the world's TB cases. Geographically the burden of TB is highest in Asia and Africa. India and China combined have almost 40% of the world's TB cases. Globally 3.7% of new cases and 20% of previously treated cases are estimated to have multi-drug-resistant-tuberculosis (MDR-TB). In India, estimated percent of new TB cases with MDR-TB is 2.1 with confidence interval of 1.5-2.7 and estimated percentage of previously treated TB cases with MDR-TB is 15.0 with confidence interval of 13 to 17. [1]

In India, revised national tuberculosis control programme (RNTCP) adopting internationally recommended directly observed treatment short course (DOTS) was started in a phased manner in 1993 by the Government of India and was successfully expanded to the whole of India by March 2006. RNTCP has been adhering to the global targets of 70% case detection rates and >85% success rates. [2]

A recurring and pertinent question is whether the number of MDR-TB is increasing, decreasing or stable following implementation of RNTCP in India. Unfortunately, there is not enough reliable data from India to provide a determinative assessment. Trends showing drug-resistance pattern are also needed to understand direction of TB control programme. The drug-resistance pattern in the state of Uttar Pradesh (UP), India, is not documented yet, which may be important to review. Here, we are reporting the prevalence of MDR and drug-resistant TB in previously treated cases of pulmonary tuberculosis following launch of RNTCP in the whole of UP.

 Materials and Methods



This is a prospective observational study. Isolates of Mycobacterium tuberculosis, from patients of pulmonary tuberculosis, who were treated with antitubercular drugs for more than 4 weeks (prescription available with patients) were enrolled for further testing. Detailed history of the patients like existing comorbidities, etc., could not be collected from the patients. Study was done at TB laboratory, Department of Microbiology, K G Medical University. Specimen collection and processing was done as per standard protocols. Briefly,

 



hree sputum samples (one on spot and two early morning samples) were collected in sterile container from each patient (minimum 5 ml of sputum). All sputum samples were examined for presence of acid-fast bacilli (AFB) by Ziehl- Neelsen method. Single sputum sample from each patient, showing maximum numbers of AFB, was decontaminated by Petroff's method, and inoculated on to two Lowenstein- Jensen (L-J) tubes, and one L-J tube containing Paranitrobenzoic acid (PNB) [3],[4],[5] The culture bottles were incubated at 37 0 C for 12 weeks. These bottles were read after 48 hours of incubation to rule out contamination. Thereafter bottles were read weekly; no growth in the LJ tube after 12 weeks of incubation was treated as negative. If growth was present in the presence of PNB, isolate was treated as Mycobacterium other than tuberculosis (MOTT) and was excluded from the study. If growth was present in the LJ tube but not in the PNB tube isolate was treated as M. tuberculosis. Drug susceptibility testing (DST) was performed on LJ medium according to the conventional 1% proportion method. [4] The concentration of anti-TB drugs used was; 0·2 μg/ml for H, 40 μg/ml for R, 4 μg/ml for S, 2 μg/ml for E, 2.0 μg/ml for OFX and 30 μg/ml for KM. All the drugs and chemicals were procured from Sigma, USA. External quality control for first-line drugs DST was provided by the National JALMA Institute for Leprosy and Other Mycobacterial Diseases, Agra (India). A standard H37Rv strain was used as the quality control strain for each new batch of medium throughout the study.

 Result



Total 2496 isolates of M. tuberculosis, isolated in the laboratory during 2009-12 (4 years) were tested for drug sensitivity against four first-line drugs i.e., Streptomycin, Rifampicin, Ethambutol and isoniazid (S R E H), of which 1139 isolates (45.6%) were sensitive (pan sensitive) and 370 (14.8%) were resistant to all four drugs (pan resistant). Total 695 isolates (27.8%) were resistant to both isoniazid and rifampicin (MDR). Maximum resistance was with isoniazid (n = 1069, 42.8%) followed by streptomycin (n = 840, 33.7%), rifampicin (n = 742, 29.7%) and ethambutol (n = 613, 24.6%). Year-wise stratified analysis is shown in [Table 1].{Table 1}

A decline in number of MDR strains and individual drug resistance is visible over 4 years. Total MDR strains in the year 2009, 2010, 2011 and 2012 were 35.6%, 30.8%, 26.7% and 22.8%, respectively. Pan-sensitive strains in the year 2009, 2010, 2011 and 2012 were 42.3%, 39.6% 47.7% and 46.8%, respectively. Total pan resistance was 22.7%, 19.0%, 10.6% and 13.3% in the years 2009, 2010, 2011 and 2012, respectively. Streptomycin resistance in the year 2009, 2010, 2011 and 2012 was 40.1%, 42.8%, 28.2% and 32.1%, respectively. Resistance to isoniazid was 47.9%, 40.6%, 41.8% and 42.7% in the years 2009, 2010, 2011 and 2012, respectively. Resistance to rifampicin in the year 2009, 2010, 2011 and 2012 was 39.2%, 35.3%, 17.1% and 21.8%, respectively. Ethambutol resistance was 36.7%, 35.3%, 17.1% and 21.80% in the years 2009, 2010, 2011 and 2012, respectively [Table 1].

 Discussion



There have been a number of reports on drug-resistance TB in India, but most studies were undertaken using non-standardised methodologies with bias and small samples usually from tertiary level care facilities. [6],[7],[8],[9],[10],[11],[12] To obtain a more precise estimate of Multi-Drug Resistant TB (MDR-TB) burden in the country, RNTCP carried out drug resistance surveillance (DRS) surveys in accordance with global guidelines in selected states, Gujarat (56 million population) and Maharashtra (107 million) in 2005-2006 and Andhra Pradesh (81 million) in 2007-2008. The results of these surveys indicate prevalence of MDR-TB to be low i.e., less than 3% amongst new cases and 12-17% in re-treatment cases. These surveys also indicate that the prevalence of MDR-TB is stable in the country as the previous studies conducted by TRC, Chennai and NTI, Bangalore have shown a similar prevalence figures. Based on the results of Gujarat, Maharashtra and Andhra Pradesh DRS Survey, estimated proportion of MDRTB is 2.1% (1.5%-2.7%) in new TB cases and 15% (13%-17%) in previously treated cases. As compared to global rates, the proportions of MDR-TB are lesser in India. [13]

In the present study prevalence of drug resistant TB especially MDR-TB is much higher than reported in RNTCP report 2012. [13] We are a tertiary care centre, catering to one of the most populous states of India. TB laboratory receives samples referred from all over the surrounding districts of UP for Mycobacterial culture and sensitivity. This is the only accredited culture and DST laboratory in the state and is biased to choose the samples from those cases which are difficult to treat, in order to manage the work overload. Therefore, the figures shown here may not be truly representative of the population. However, the data shown here is only taken into account after laboratory has reached the accredited status, to make sure that there are no quality issues. As also reported from all most all the tertiary centres levels of MDR-TB are much higher in both previously untreated and first-line treatment-failure cases than those projected by national estimates. [6],[7],[8],[9],[10],[11],[12] All of these isolates were from patients of pulmonary TB, who had received antitubercular drugs in past, many of them had even completed the treatment. These patients were from both public and private sector. They carried a prescription of antitubercular drug written by a physician; however, it was not possible to decipher the degree of adherence or the quality of drugs taken, as many of these cases were not on directly observed therapy as recommended in RNTCP. Here we are unable to comment on causes and issues related to drug resistant TB due to non-availability of clinical details.

Most of the studies from India [6],[9],[10] and rest of the world [14] have shown a worsening trend, showing an increase in number of drug-resistant cases. However, we have found a decreasing trend. Reporting periods of majority of previous studies are 1990-2006; while we are reporting recent data (2009-2012) collected after 3-7 years after RNTCP was implemented in whole of the country. Impact of any programme may be visible after certain years of implementation. At this point we also cannot ignore the fact that with implementation of DOTS plus in state of UP and with wider availability of good quality laboratory testing facility, awareness among physicians and patients has increased and reference in the laboratory has increased since 2011 as also visible in the data [Table 1]. There is a possibility of population variation from year to year. Another recent study from Taiwan has also shown effectiveness of DOTS and DOTS Plus in reducing drug resistance. [15]

The drug-resistance pattern reported from laboratory to laboratory and from time to time may vary substantially. However, the decline in drug resistance over last 4 years after implementation of DOTS, appears promising.

 Acknowledgement



The authors acknowledge the help of staff of Intermediate reference laboratory, KGMU, Lucknow, UP, India for their support in performing the tests.

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