A study on pre-XDR & XDR tuberculosis & their prevalent genotypes in clinical isolates of Mycobacterium tuberculosis in north India

Abstract

Background & objectives:Pre-extensively drug resistant (pre-XDR) and extensively drug resistant tuberculosis (XDR-TB) have been areas of growing concern, and are posing threat to global efforts of TB control. The present study was planned to study the presence of pre-XDR and XDR Mycobacterium tuberculosis and their genotypes in clinical isolates obtained from previously treated cases of pulmonary TB.Methods:A total of 219 isolates obtained from previously treated cases of pulmonary TB were subjected to first-line (streptomycin, isoniazid, rifampicin and ethambutol) and second-line (ofloxacin, kanamycin, capreomycin and amikacin) drug susceptibility testing on solid Lowenstein-Jensen medium by proportion method. Genotyping was done for pre-XDR and XDR-TB isolates using 12 loci Mycobacterial Interspersed Repetitive Units-Variable Number Tandem Repeats (MIRU-VNTR).Results:Multi-drug resistance was observed in 39.7 per cent (87/219) isolates. Pre-XDR and XDR M. tuberculosis isolates amongst 87 multi-drug resistant (MDR) TB isolates were 43 (49.4%) and 10 (11.4%), respectively. Two most dominant genotypes among pre-XDR and XDR M. tuberculosis isolates were Beijing and Delhi/CAS types.Interpretation & conclusions:Resistance to second-line anti-tubercular drugs should be routinely assessed in areas endemic for TB. Similar genotype patterns were seen in pre-XDR and XDR-TB isolates. Beijing and Delhi/CAS were predominant genotypes.

Genotype analysis of ofloxacin-resistant multidrug-resistant Mycobacterium tuberculosis isolates in a multicentered study from India

“…The reason for this was not clear from the data we had and a study with a significantly higher number of isolates would be able to explain the causality of this. In all, OFX resistance was higher in all regions studied, which was in line with previous studies 5 25 26 .…”

“…Our study showed a predominance of Beijing/CAS and EAI genotypes and an association between MDR and OFX resistance-conferring mutations and the Beijing genotype. A study from north India also observed Beijing as dominant genotype along with CAS_Delhi among OFX-resistant MDR-TB isolates 5 . While correlating the association of gyrA mutations in various lineages another study from north India found that the association of Beijing isolates was significantly high ( P =0.0006) with gyrA gene mutations 27 .…”

“…XDR-TB is defined as MDR-TB with additional resistance to any FQs and a second-line injectable drug such as kanamycin, amikacin, or capreomycin 1 . Dispersed but scanty reports are available from India about XDR-TB 2 3 4 5 , but are not enough to estimate the extent and magnitude of XDR-TB. Reasons primarily include the lack of facilities for second-line drug susceptibility determination, availability of standardized protocols with desired facilities and our focus on primary care of TB patients.…”

The study on the association between Beijing genotype family and drug susceptibility phenotypes of Mycobacterium tuberculosis in Beijing

“…The molecular epidemiology methods has been proven playing an important role in TB control and study 4 , 5 . Among these, spoligotyping has been considered as a powerful tool to differentiate M .…”

Pre-extensively drug-resistant tuberculosis spondylodiscitis in an immunocompetent patient: a case report

“…PreXDR-TB is defined as MDR-TB with resistance to either an FQ or a second line injectable (SLI), but not both [ 3 ]. The burden of pre-XDR-TB is considerable and represents a threat to MDR-TB control [ 4 , 5 ]. The World Health Organization (WHO) estimated 484 000 incident cases of MDR/RR-TB (MDR or rifampicin-resistant TB) in 2018 [ 1 ].…”