Detection of multidrug resistance and extensively drug resistance among smear-negative extrapulmonary tuberculosis cases in a reference laboratory

Background: Extrapulmonary tuberculosis (EPTB) constitutes about 15%–20% of all cases of TB. Patients with EPTB are more likely to have negative sputum smear results. It is often hard to diagnose because of difficulty of sampling and paucibacillary nature of samples. Methods: Smear negative extra pulmonary (EP) specimens were included in the study. An attempt was made to recover M. tuberculosis (MTB) from such EP specimens using rapid liquid culture (MGIT 960). Molecular Line probe assay (LPA) was used to determine the resistant for first line drugs, and second line drug resistant was determined using liquid culture. Results: Culture positivity was found in 21.3% (133/623) of specimens; of these 95.48% (127/133) were found to be MTB and 4.51% (6/133) of specimens were found to be non tubercular mycobacteria. Among MTB detected 18.9% of specimens were multi drug resistant, 3.90% were Rifampicin mono-resistant and 13.30% were Isoniazid resistant. Second line DST (N=29) was performed for Kanamycin and Ofloxacin; of which 3.4 % was found to be resistant to both drugs, 3.4 % was found to be resistant to Ofloxacin and 93.1% were sensitive to both drugs. Conclusion: Large percentage of drug resistance was observed in the study. Early recovery of MTB and determination of its drug resistance helped in early initiation of treatment and controlled further transmission of drug-resistant TB in the population.