Conclusion NTM were present in at least 1.3% of all smear positive samples. It is important for public health programs to recognize the avoidable burden on logistics, infrastructure and finances caused by this. Detection and quantification of this burden would help design an appropriate strategy for optimal tuberculosis control.

Background & objectives:Mycobacterium tuberculosis complex may sometimes not be detected in sputum samples of suspected multidrug-resistant tuberculosis (MDR-TB) patients by line probe assay (LPA) even though they are smear positive for acid-fast bacilli (AFB). This retrospective analysis was attempted to understand and document our experience with LPA for detection of M. tuberculosis complex and diagnosis of MDR-TB under programmatic conditions.Methods:One thousand two hundred and ninety four sputum samples of MDR-TB suspects that were smear positive for AFB, and received from February to November 2013, were tested by LPA for the presence of M. tuberculosis complex and resistance to isoniazid (INH) and rifampicin as per the diagnostic mandate of an accredited reference laboratory. As per the mandate, those samples that were negative for M. tuberculosis complex were cultured, and the growth again tested by LPA. A retrospective analysis of the results was carried out.Results:M. tuberculosis complex could be detected in 1217 (94.04%) but not in 77 (5.9%) of smear-positive sputum samples. Of the 1217 positive samples, 232 (19.1%) were MDR, 130 (10.6%) were rifampicin monoresistant and 101 (8.3%) were INH monoresistant. Seven hundred and fifty four (61.9%) strains were found to be pansensitive. Overall, 5.1 per cent of the sputum samples were negative for M. tuberculosis complex by LPA and culture. In at least 10 (0.77%) sputum samples smear positive for AFB, M. tuberculosis complex could not be identified by LPA though M. tuberculosis was present, as evidenced by culture positivity.Interpretation & conclusions:LPA is a robust technique for diagnosis of drug-resistant TB that has provided the basis for rapid and effective control of drug-resistant TB in India. While the reasons for concomitantly negative LPA and culture results of smear-positive sputum samples from MDR-TB suspects may be many, the possible presence of non-tubercular mycobacteria in these samples and the likelihood of inappropriate therapy in these patients cannot be ruled out. Addition of culture to the diagnostic algorithm may enhance the diagnostic yield.

Results Mutations were identified in 269 (37.6%) samples, as follows: 55 (7.6%) samples had mutations conferring resistance to only isoniazid, 84 (11.6%) had mutations conferring resistance to only rifampicin and 130 (18%) isolates had mutations conferring resistance to both isoniazid and rifampicin.The most frequent mutation in the rpoB gene was at codon S531L, seen in 141 (19.5%) isolates. The most frequent mutation in the katG gene was at codon S315T1, seen in 151 (20.9%) isolates; and in the inhA gene at codon C15T, seen in 21 (2.9%) isolates. Some unidentified mutations were also observed. ConclusionThe patterns and the frequency of the mutations identified in this study indicate the most frequent mutations at S531L codon in the rpoB gene, S315T1 codon in the katG gene and C15T codon in the promoter region of the inhA gene. Controlling the emergence and spread of MDR TB requires an understanding of the evolution of these mutations.

Background Drug-resistant TB is a serious public health problem in India. Pre-existing resistance to fluoroquinolones (FQs) and second-line injectable drugs (SLIDs) in strains of Mycobacterium tuberculosis (MTB) resistant to rifampicin (RIF) and/or isoniazid (INH) contributes to treatment failures and consequent transmission of drug-resistant TB. A baseline assessment of resistance of MTB to FQs and SLIDs may help guide policies to further improve management of drug-resistant TB in India. This study aims to determine the prevalence of resistance to FQs and SLIDs among MTB strains having RIF and/or INH resistance in central India. Method A total of 1032 smear positive sputum samples were subjected to line probe assay (GenoType MTBDRsl version 2) to test for resistance to FQs and SLIDs, according to the integrated diagnostic algorithm of the revised national TB control programme. Results Of 1032 samples, 92 (8.91%) were not interpretable and hence excluded, 295 (31.38%) were resistant to FQs alone, 13 (1.38%) were resistant to SLIDs alone, 15 (1.59%) were resistant to both FQs as well as SLIDs and 617 (65.63%) were sensitive to both FQs and SLIDs. The most common mutations in gyrA and gyrB genes were observed at codons D94G and E540V, respectively. Mutations at codon A1401G in rrs genes and in the C-14 T region of eis genes were most frequently observed. Conclusion High levels of FQ resistance points towards indiscriminate use of this class of drugs. Regulation for judicial use of FQs is an urgent requirement.

Background & objectives: A combination of resistant and susceptible Mycobacterium tuberculosis (MTB) isolated from clinical specimens is referred to as heteroresistance. Heteroresistance leads to difficulties in drug resistance testing and may adversely affect treatment outcomes. The present study estimated the proportion of heteroresistance among MTB in clinical samples of presumptive drug-resistant tuberculosis (TB) patients in Central India. Methods: A retrospective analysis of data generated from line probe assay (LPA) at a tertiary care hospital in Central India between January 2013 and December 2018 was carried out. A heteroresistant MTB in a sample was indicated by the presence of both wild-type and mutant-type patterns on an LPA strip. Results: Data analysis was carried out on interpretable 11,788 LPA results. Heteroresistance in MTB was detected in 637 (5.4%) samples. Of these, heteroresistance in MTB was detected in 413 (64.8%), 163 (25.5%) and 61 (9.5%) samples with respect to rpoB , katG and inhA genes, respectively. Interpretation & conclusions: Heteroresistance is considered a preliminary step in the development of drug resistance. Delayed or suboptimal anti-tubercular therapy in patients with heteroresistance of MTB may elicit full clinical resistance and negatively impact the National TB Elimination Programme. Further studies are, however, needed to determine the impact of heteroresistance on treatment outcomes in individual patients.