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is an automatic methodology that uses the polymerase chain reaction to detect in less than two hours the presence of Mycobacterium tuberculosis and also informs about the sensibility to rifampicin. This technology has good sensibility and even better specificity in respiratory samples. In non-respiratory samples the sensibility is lower. We analyzed the results of samples sent to the Laboratory of Tuberculosis of the Instituto Nacional del Tórax-Chile (National Thorax Institute) during the last two years since we started to use this technology. We analyzed 529 samples, 384 (73%) of them were respiratory in origin and 145 (27%) were non-respiratory. Only 43 samples were positive for Mycobacterium tuberculosis, 33 from respiratory samples, and 10 from other sources. 17 smear negative samples were culture positive for Mycobacterium tuberculosis; 15 of them were detected by Xpert; 351 samples were culture negative, 17 of them were positive by Xpert, the majority in patients under treatment for tuberculosis or with old tuberculosis. Ten of 10 culture positive patients from non-respiratory samples were positive with Xpert. The interpretation of Rifampicin resistance, when its prevalence in a given population is low, like is the case in Chile, requires confirmation by using standard methods.

The difficult road to achieve sanitary tuberculosis control Tuberculosis continues to be a worldwide prevalent disease. Chile has established a tuberculosis control program since the earliest 70s which contributed to decrease the annual incidence of tuberculosis by 50% every decade, reaching the rate of 20 per 100.000 inhabitants the year 2000 ("early phase of tuberculosis elimination as a public health problem"). Unfortunately since this time the descent rate is becoming slower and between years 2009-2011 has achieved a stationary rate of 13 x 100.000. This deterioration in the epidemiological situation of tuberculosis in Chile runs in parallel with the successive reductions in the budget assigned for its control. A higher incidence of tuberculosis in high risk groups (HIV population, migrants, prisoners and elderly people) were not responsible for this epidemiologic deterioration. Lack of diagnosis in smear positive pulmonary tuberculosis patients is the most important source of persistent community infection. Only 25% of the estimated goal of sputum smear screening among medical consultations in primary care was achieved. Between the years 2006-2010 193.416 less sputum smear examinations were done. This means that nearly 966 smear positive tuberculosis patients were no identified as we know that about 0.5% smears are positive in this setting. A shortage of funds for tuberculosis in our country could increase its incidence as it was shown in Brazil, Cuba and Uruguay and would demand larger resources to strengthen the tuberculosis program. This epidemiological scene is worse in the Metropolitan Region where 40% of the country population concentrated 60% of the incidence of tuberculosis the year 2011. In this area we found counties with the highest rates. There is the need to strengthen the tuberculosis program in these areas and to organize teams in the primary care settings in order to increase case finding through the performance of sputum smears in symptomatic adult patients.

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