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The increasing burden of drug-resistant tuberculosis (TB) poses an escalating threat to national TB control programs. To assist appropriate treatment for TB patients, accurate and rapid detection of drug resistance is critical. The GeneChip test is a novel molecular tool for the diagnosis of TB drug resistance. Performance-related data on GeneChip are limited, and evaluation in new and previously treated TB cases has never been performed. We evaluated the diagnostic performance of GeneChip in detecting resistance to rifampin (RMP) and isoniazid (INH) and in detecting multidrug-resistant tuberculosis (MDR-TB) in comparison with standard drug susceptibility testing (DST) and compared the results in a group of previously treated and newly detected TB patients in an urban area in southeastern China. One thousand one hundred seventy-three (83.8%) new cases and 227 (16.2%) previously treated cases were collected between January 2011 and September 2013. The GeneChip showed a specificity of 97.8% and a sensitivity of 94.8% for detection of RMP resistance and 97.3% and 70.9%, respectively, for INH resistance in new cases. For previously treated cases, the overall sensitivity, specificity, and agreement rate are 94.6%, 91.3%, and 92.1%, respectively, for detection of RMP resistance and 69.7%, 95.4%, and 86.8%, respectively, for INH resistance. The sensitivity and specificity of MDR-TB were 81.8% and 99.0% in new cases and 77.8% and 93.4% in previously treated cases, respectively. The GeneChip system provides a simple, rapid, reliable, and accurate clinical assay for the detection of TB drug resistance, and it is a potentially important diagnostic tool in a high-prevalence area. T uberculosis (TB) is an infectious disease caused by the bacillusMycobacterium tuberculosis and remains a major global health problem. In 2012, the World Health Organization (WHO) estimated an incidence of 8.6 million new TB cases and 1.3 million TB deaths (just under 1.0 million among HIV-negative people and 0.3 million HIV-associated TB deaths) (1).The emergence of drug-resistant TB (especially multidrug-resistant TB [MDR-TB], defined as resistance to both rifampin [RMP] and isoniazid [INH]) represents a serious threat to TB control efforts worldwide. Globally, 3.6% of new TB cases and 20.2% of previously treated cases are estimated to have MDR-TB (1, 2). Acid-fast bacillus (AFB) smear microscopy is the most common method for diagnosing TB. However, low sensitivity and an inability to detect smear-negative pulmonary cases limit the usefulness of this technique (3, 4). Diagnosis based on culture is the reference standard, but results take weeks to obtain. Conventional drug susceptibility testing (DST) can provide definitive results, but this approach is time-consuming and usually requires several weeks to produce susceptibility profiles, which can lead to inadequate treatment and further acquired drug resistance during this period (5, 6). Therefore, highly sensitive and specific, easy-toapply, quick, and cost-effective methods are needed in the ...

ObjectiveTo evaluate a biochip system in determining isoniazid and rifampicin resistances of Mycobacterium tuberculosis in sputum samples in a Chinese population.MethodsWe assembled 907 sputum smeared positive specimens of tuberculosis patients in total. Each sample would be separated into two parts for culture and biochip assay simultaneously. And those cultured positive and having full drug resistance results would be used as reference. The McNemar χ2 test was adopted for evaluating the paired 2×2 table.ResultsCompared with drug sensitivity test, the agreement rates of the two methods in detecting rifampicin and isoniazid resistances were 93.37% and 94.49%, respectively. The sensitivity and specificity of biochip in detecting isoniazid were 74.31% and 96.92%, respectively. Meanwhile, the sensitivity and specificity for rifampicin were 79.76% and 96.53%, respectively. For multi-drug resistance, the sensitivity and specificity were 64.62% and 97.75%, respectively.ConclusionsThe biochip system is a rapid and accurate method for drug resistant tuberculosis diagnosis using sputum samples directly, especially for rifampicin resistance detection.

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