Introduction. Multidrug resistance tuberculosis (MDR TB), the combined resistance of Mycobacterium tuberculosis to isoniazid (INH) and rifampin (RFM) is a major public health problem in India as it ranks second among the MDR-TB high burden countries worldwide. WHO recommends RFM resistance as a “surrogate marker” for detecting MDR. FNAC is the most widely used noninvasive investigative technique for TB lymphadenitis. Real-time polymerase chain reaction, an extremely versatile technique can be used for the timely detection and treatment of MDR TB by assessing RFM resistance status in the FNAC samples of TB lymphadenitis. Aim. To assess the status of rpoB gene by real-time PCR in FNAC samples of TB lymphadenitis. Materials and Methods. Thirty FNAC samples from patients with persistent LAP or appearance of new LAP after 5 months or more of Anti Tubercular Treatment were assessed for status of rpoB gene by Real-Time PCR using probe covering the “hot spot resistance” region of the rpoB gene. Result. By using probe covering codons 531 and 526 of rpoB gene, we could detect 17 of 30 (56.7%) rifampin resistant isolate. The PCR could detect Mtb DNA in 100% of cases. Conclusion. Use of molecular methods like Real-Time PCR for detection of MDR-TB in FNAC samples is time saving, logical and economical approach over the culture based method. 1. Introduction Multidrug resistant tuberculosis (MDR-TB) is a major public health problem in India as it ranks second among the MDR-TB high-burden countries worldwide [1]. MDR-TB is defined as the combined resistance of Mycobacterium tuberculosis (Mtb) to isoniazid (INH) and rifampin (RFM). However, resistance to RFM, the first-line antituberculosis drug is considered to be more critical since it usually occurs in combination with other drugs specially INH. Hence, WHO has recommended RFM resistance as a “surrogate marker” for detecting MDR [2]. Ninety-six percent of RFM-resistant Mtb strains possess genetic alterations within an 81？bp “rifampin resistance-determining region” (RRDR) in the rpoB gene [3, 4], corresponding to codons 507 to 533. Real-time polymerase chain reaction (PCR) is a rapid and reliable method that enables both the amplification and the detection of mutations by using fluorescently labelled DNA probes [5]. The assessment of RFM resistance in cases of TB lymphadenitis (LAP), the most frequent (30–52%) cause of LAP in developing countries [6], is important for the timely detection and efficient treatment of such cases. Fine needle aspiration cytology (FNAC), a widely practised noninvasive, safe, simple, and
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