Genotypic analysis of multidrug-resistant tuberculosis isolates from extra pulmonary tuberculosis cases in tertiary care centers in Northern India

Abstract

Objective/backgroundMultidrug-resistant tuberculosis (MDR-TB) is a major public health problem. The diagnosis of MDR-TB is of paramount importance in establishing appropriate clinical management and infection control measures. Rapid detection of MDR-TB allows the establishment of an effective treatment regimen, minimizes the risk of further resistance, and limits the spread of drug-resistant strains. The aim of this study is to determine the genotypic characterization of MDR-TB isolates from extra pulmonary tuberculosis (EPTB) cases in tertiary care centers in Northern India. MethodsThis study was a prospective study. In total, 756 extra pulmonary specimens were collected from patients with suspected tuberculosis in two tertiary care hospitals in Northern India. Specimens were processed for Ziehl–Neelsen staining, culture, and first-line drug susceptibility test using BacT/ALERT 3D system and GenoType MTBDRplus assay for genotypic analysis of MDR-TB. MDR-TB strains were further processed by novel multiplex polymerase chain reaction for rapid identification of Beijing and non-Beijing strains associated with MDR-TB. ResultsOf these 164 Mycobacterium tuberculosis complex isolates, 100 (60.9%) strains were fully susceptible and 64 (39.1%) strains were resistant. We noted that the prevalence of MDR-TB among EPTB was 22 (13.4%). The prevalence of MDR-TB was 11.4% in new cases and 19.1% in previously treated cases (p<0.05). Ser531Leu mutation was the predominant mutation noted, and Ser315Thr mutation was more prevalent among the MDR-TB isolates (p<0.05). The proportion of Beijing strains was significantly higher among MDR-TB strains (72.7%, p<0.05). ConclusionThe prevalence (13.4%) of MDR-TB among EPTB was high, and the most prominent mutations in rpoB, katG, and inhA genes were S531L (67.3%), S315T1 (94.5%), and C15T (20%), respectively. Beijing stains are significantly associated with MDR-TB among EPTB in this region. We found that the transmission of prominent mutations contributes to an unexpected increase in primary resistance, including MDR-TB cases in Northern India.