Prevalence of multidrug-resistant tuberculosis among Category II pulmonary tuberculosis patients.

Background & objectives: Multidrug-resistant tuberculosis (MDR-TB) has emerged as a significant global health concern. The most important risk factor for the development of MDR-TB is previous anti-tuberculosis therapy. Category II pulmonary TB includes those patients who had failed previous TB treatment, relapsed after treatment, or defaulted during previous treatment. We carried out this study to ascertain the prevalence of MDR-TB among category II pulmonary TB patients. Methods: This was a cross-sectional, descriptive study involving category II pulmonary TB patients diagnosed between 2005 and 2008. All sputum-positive category II TB cases were subjected to mycobacterial culture and drug-susceptibility testing (DST). MDR-TB was defined as TB caused by bacilli showing resistance to at least isoniazid and rifampicin. Results: A total of 196 cases of sputum-positive category II pulmonary tuberculosis patients were included. Of these, 40 patients (20.4%) had MDR-TB. The mean age of MDR-TB patients was 33.25 ± 12.04 yr; 9 patients (22.5%) were female. Thirty six patients showed resistance to rifampicin and isoniazid; while 4 patients showed resistance to rifampicin, isoniazid and streptomycin. The prevalence of MDR-TB among category-II pulmonary tuberculosis patients was 20.4 per cent. Interpretation & conclusions : The prevalence of MDR-TB in category II TB patients was significant. However, nation-wide and State-wide representative data on prevalence of MDR-TB are lacking. We stress the importance of continuous monitoring of drug resistance trends, in order to assess the efficacy of current interventions and their impact on the TB epidemic.

Prevalence of multidrug-resistant tuberculosis among newly diagnosed cases of sputum-positive pulmonary tuberculosis.

Background & objectives: The prevalence of multidrug-resistant tuberculosis (MDR-TB) is increasing throughout the world. Although previous treatment for TB is the most important risk factor for development of MDR-TB, treatment-naïve patients are also at risk due to either spontaneous mutations or transmission of drug-resistant strains. We sought to ascertain the prevalence of MDR-TB among new cases of sputum-positive pulmonary TB. Methods: This was a prospective, observational study involving newly diagnosed cases of sputum-positive pulmonary tuberculosis diagnosed between 2008 and 2009 carried out in New Delhi, India. All sputum-positive TB cases were subjected to mycobacterial culture and first-line drug-susceptibility testing (DST). MDR-TB was defined as TB caused by bacilli showing resistance to at least isoniazid and rifampicin. Results: A total of 218 cases of sputum-positive pulmonary tuberculosis were enrolled between 2008 and 2009. Of these, 41 cases had negative mycobacterial cultures and DST was carried out in 177 cases. The mean age of the patients was 27.8 ± 10.2 yr; 59 patients (27%) were female. All patients tested negative for HIV infection. Out of 177 cases, two cases of MDR-TB were detected. Thus, the prevalence of MDR-TB among newly diagnosed pulmonary tuberculosis patients was 1.1 per cent. Interpretation & conclusions: MDR-TB prevalence is low among new cases of sputum-positive pulmonary TB treated at primary care level in Delhi. Nation-wide and State-wide representative data on prevalence of MDR-TB are lacking. Efforts should be directed towards continued surveillance for MDR-TB among newly diagnosed TB cases.

Prevalence of extensively drug-resistant tuberculosis among patients with multidrug-resistant tuberculosis: a retrospective hospital-based study.

Background & objective: Extensively drug-resistant tuberculosis (XDR-TB) is a difficult-to-treat form of multidrug-resistant tuberculosis (MDR-TB). High rates of XDR-TB have been reported from India. We sought to ascertain the prevalence of XDR-TB among patients with MDR-TB treated at a tertiary care centre in New Delhi, India. Methods: Case records of patients treated for MDR-TB at the All India Institute of Medical Sciences hospital, New Delhi, between 1997 and 2003 were retrospectively reviewed. All patients underwent a pretreatment drug-susceptibility testing (DST) to first- as well as second-line drugs. XDR-TB was defined as TB caused by bacilli showing resistance to rifampicin and isoniazid in addition to any fluoroquinolone and to at least one of the three following injectable drugs: capreomycin, kanamycin, and amikacin. Results: A total of 211 laboratory-confirmed cases of MDR-TB were reviewed. The mean age of the patients was 33 ± 12 yr. Fifty one (24%) patients were females. All patients were sero-negative for human immunodeficiency virus infection. Five of the 211 MDR-TB patients had XDR-TB. The prevalence of XDR-TB was 2.4 per cent among MDR-TB patients. Interpretation & conclusion: Our results showed that XDR-TB was rare among patients with MDR-TB treated between 1997 and 2003 at our centre. Unreported selection bias might have been responsible for the high prevalence of XDR-TB reported in previous hospital-based studies from India.