S K Sharma1, J Chaubey2, B K Singh2, R Sharma2, A Mittal2, A Sharma3. 1. Department of Internal Medicine, All India Institute of Medical Sciences, New Delhi, Department of Molecular Medicine, Jamia Hamdard Institute of Molecular Medicine, Hamdard University, New Delhi, Departments of General Medicine and Pulmonary Medicine, Jawaharlal Nehru Medical College, Datta Meghe Institute of Medical Sciences, Wardha. 2. Department of Internal Medicine, All India Institute of Medical Sciences, New Delhi. 3. Department of Dermatology, Venerology and Leprology, Teerthankar Mahavir University, Moradabad, India.
Abstract
BACKGROUND: xtra-pulmonary tuberculosis (EPTB) is a growing public health concern, and data on drug resistance are limited. MATERIAL AND METHODS: Specimens from 2468 clinically diagnosed EPTB patients received at the Intermediate Reference Laboratory (IRL) of a tertiary centre in India were subjected to Ziehl-Neelsen staining, Xpert® MTB/RIF testing, liquid culture and drug susceptibility testing (DST) using automated BACTEC MGIT™ 960™. Line-probe assay (LPA) was performed on all culture-positive isolates. Gene sequencing was performed on rifampicin-resistant/multidrug-resistant TB (RR/MDR-TB) and phenotypic/genotypic discrepant isolates. RESULTS: The culture positivity rate was 18.9% (483/2553). The sensitivity and specificity of Xpert in diagnosing EPTB were respectively 70.8% (95%CI 66.5-74.8) and 97.7% (95%CI 96.9-98.3), with liquid culture as the reference standard. Prevalence of RR/MDR-TB was 10.1% (49/483). Prevalence of pre-extensively drug-resistant TB (pre-XDR-TB) was 18.4% (09/49), whereas the prevalence of XDR-TB among MDR-TB patients was 2% (01/49). The sensitivity of genotypic DST for the detection of rifampicin resistance was 92.7% (95%CI 81.1-98.5) and specificity was 99.3% (95%CI 97.5-99.9), with 100% concordance between Xpert and LPA. CONCLUSION: The burden of drug resistance, including M/XDR-TB, among EPTB patients is high. Novel molecular tests can help in early diagnosis and treatment to prevent disease progression and amplification of resistance.
BACKGROUND:xtra-pulmonary tuberculosis (EPTB) is a growing public health concern, and data on drug resistance are limited. MATERIAL AND METHODS: Specimens from 2468 clinically diagnosed EPTB patients received at the Intermediate Reference Laboratory (IRL) of a tertiary centre in India were subjected to Ziehl-Neelsen staining, Xpert® MTB/RIF testing, liquid culture and drug susceptibility testing (DST) using automated BACTEC MGIT™ 960™. Line-probe assay (LPA) was performed on all culture-positive isolates. Gene sequencing was performed on rifampicin-resistant/multidrug-resistant TB (RR/MDR-TB) and phenotypic/genotypic discrepant isolates. RESULTS: The culture positivity rate was 18.9% (483/2553). The sensitivity and specificity of Xpert in diagnosing EPTB were respectively 70.8% (95%CI 66.5-74.8) and 97.7% (95%CI 96.9-98.3), with liquid culture as the reference standard. Prevalence of RR/MDR-TB was 10.1% (49/483). Prevalence of pre-extensively drug-resistant TB (pre-XDR-TB) was 18.4% (09/49), whereas the prevalence of XDR-TB among MDR-TBpatients was 2% (01/49). The sensitivity of genotypic DST for the detection of rifampicin resistance was 92.7% (95%CI 81.1-98.5) and specificity was 99.3% (95%CI 97.5-99.9), with 100% concordance between Xpert and LPA. CONCLUSION: The burden of drug resistance, including M/XDR-TB, among EPTB patients is high. Novel molecular tests can help in early diagnosis and treatment to prevent disease progression and amplification of resistance.