Significance and Impact of the Study: The Xpert MTB/RIF Ultra is one of the most recent advancements in molecular diagnostics with higher reported sensitivity compared to its predecessor, the Xpert MTB/ RIF assay. Studies evaluating the diagnostic performance of Xpert MTB/RIF Ultra in children with suspected tuberculosis (TB) are sparse. Additionally, all available studies have been conducted retrospectively on banked/frozen samples which may affect the results. The present study, to the best of our knowledge, is the first to perform prospective evaluation of Xpert MTB/RIF Ultra in comparison with the Xpert MTB/RIF assay in pediatric population. Its translational impact lies in the potential use of Xpert MTB/RIF Ultra as an ancillary test for diagnosis of TB in this patient group.

The TB-LAMP assay showed high sensitivity and specificity with limited requirement of testing infrastructure, and is thus a promising diagnostic tool for TB diagnosis in resource-poor settings.

Tuberculosis (TB) remains a main hurdle for national programs due to increase in drug resistance to antitubercular drugs. World Health Organization (WHO)-endorsed Line Probe Assay, Genotype MTBDRsl Ver 2.0, gives opportunity for rapid diagnosis and molecular characterization of different mutations in drug targets of fluoroquinolone (FQ) and second-line injectable drugs (SLID). We, retrospectively, analyzed the data of Genotype MTBDRsl Ver 2.0 from January 2018 to June 2018. A total of 863 isolates of Mycobacterium tuberculosis, 687 rifampicin resistant and 176 isoniazid resistant only, were screened for drug resistance in FQ and SLID. All the isolates were tested for Genotype MTBDRsl Ver 2.0 according to the manufacturer's instructions. The FQ and SLID resistance were detected in 295 (34.2%) and 70 (8.1%) isolates, respectively. Among newly diagnosed and followup rifampicin-resistant TB (RR TB) patients, the FQ resistance was 25.8% and 44.5%, respectively. The most common mutation (42.7%) in FQ-resistant isolates was MUT3C in gyrA gene. Both SLID and FQ resistance were detected in 59 (6.8%) RR TB isolates. The mono SLID resistance was detected in 12 (1.7%) isolates of RR TB. Genotype MTBDRsl Ver 2.0 assay is a rapid and important tool for the diagnosis and molecular characterization of second-line drug resistance under programmatic conditions.

A B S T R A C TRapid detection of drug resistance in Mycobacterium tuberculosis is important for the successful treatment of tuberculosis. Fluoroquinolone and aminoglycoside resistance detection by molecular methods becomes more complex due to cross resistance among them. Thus, we aimed to determine cross-resistance and mutations in resistance genes for these drugs. A total of 336 multidrug-resistant tuberculosis (MDR-TB) cases received in Mycobacteriology laboratory were screened for phenotypic drug sensitivity testing for second-line drugs, i.e., ofloxacin, amikacin, kanamycin, and capreomycin. Molecular characterization of resistance was done by DNA sequencing of gyrA gene for fluoroquinolones (FQ), and multiplex allele-specific polymerase chain reaction (PCR) and PCR restriction fragment length polymorphism (RFLP) of rrs gene for aminoglycosides. Of 336 MDR-TB isolates, 12 were extensively drug-resistant tuberculosis and 219 were sensitive to all the drugs tested. Ofloxacin, amikacin, kanamycin, and capreomycin resistance was detected in 101 (30.1%), 23 (6.8%), 27 (8.1%), and 19 (5.6%) cases, respectively. Eight different mutations were detected in gyrA gene in ofloxacin-resistant isolates and A1401G nucleotide change in rrs gene were seen in 55.6% (15/27), 65.2% (15/23), and 68.4% (13/29) for kanamycin-, amikacin-, and capreomycin-resistant isolates, respectively. Information on second-line drug resistance-associated mutations could potentially be used for development of newer rapid diagnostic tests.

Tuberculosis (TB) diagnosis in children still remains a challenge in developing countries. We analyze the performance of Xpert MTB/RIF assay for the diagnosis of pediatric TB under programmatic conditions. We retrospectively analyzed the performance of Xpert MTB/RIF assay from February 2016 to March 2018. A total 2678 samples from TB suspects below 14 years were received in the laboratory and were frontline tested by Xpert MTB/RIF assay according to the manufacturer's instructions. If sample was sufficient, the smear microscopy and culture were performed as per standard World Health Organization's guidelines. The smears and cultures were performed in 2178 and 588 samples, respectively. Among 2678 samples, 68 were rejected, Xpert MTB/RIF assay was positive in 357/2610 (13.6%) cases, while the smear was positive in 81/2178 (3.3%) cases. The sensitivity of smear and Xpert MTB/RIF when compared with culture was 24.6% (14.1-37.8%) and 81% (68.6-90.1%), respectively. The diagnostic accuracy of Xpert MTB/RIF and smear was 97.1% and 92.2%, respectively. Thirty samples (8.5%) were detected as rifampicin resistance by Xpert MTB/RIF assay. The Xpert MTB/RIF increased the detection rate up to fourfold when compared with smear microscopy. Xpert MTB/RIF assay is the most rapid, sensitive, and specific method for microbiological confirmation and rifampicin resistance detection in pediatric tuberculosis.