Abstract
Tuberculosis (TB) remains as one of the deadliest diseases after HIV globally with 95 % of deaths confined to low-and-middle income countries. Pakistan is fifth among the 22 high-burden TB countries with the incidence rate of 230/100,000 persons, however, studies related to prevalent Mycobacterium tuberculosis strains and their spread, drug resistance pattern and evolutionary genetics are inadequate. The present study was undertaken to highlight the circulation of M. tuberculosis strains causing drug resistant TB in our community by targeting the molecular marker IS6110 and then characterization of these strains as Beijing and Non-Beijing genotypes. Sputum samples from 102 MDR TB suspects from different cities of Punjab were collected and their record was stored in a database. Sputum samples were evaluated by Ziehl Neelson staining and cultured on Lownstein Jensen medium by Modified Petroff’s method. DST was performed for first-line anti-mycobacterial drugs by indirect proportion method. Mycobacterium tuberculosis isolates were investigated for the presence of IS6110 and further identification as Beijing, Non-Beijing or mixed genotype. Percentage of male and female patients was found to be 58.8 and 41.2 % respectively. DST showed resistance of 93 % of isolates to isoniazid and rifampicin. All of the isolates showed positive results for IS6110 amplification. Based on PCR amplification of Beijing and non-Beijing primer sets 4.9 % of the patients showed infection with pure Beijing isolates, 14.7 % with both Beijing and non-Beijing isolates and 80.3 % with pure non-Beijing isolates. Analysis of IS6110 and Beijing sequences showed the presence of putative transposase conserved domain while non-Beijing sequences were epitomized with RAMP_I_III superfamily domain (CRISPR-associated protein family). TB in Pakistan is predominantly caused by Non-Beijing genotypes, but Beijing strains showed incessant circulation in our community as both single and mixed (co-infecting Non-Beijing and Beijing) strains.
Highlights
Tuberculosis (TB) continues as one of the deadliest contagious diseases across the globe
Pakistan is fifth among the 22 high-burden TB countries with the incidence rate of 230/100,000 persons, studies related to prevalent Mycobacterium tuberculosis strains and their spread, drug resistance pattern and evolutionary genetics are inadequate
As mixed infection may be common in high burden drug resistant TB countries, so the aim of the present study was to elucidate the drug resistant pattern of multi-drug resistant MTB strains in our community, genotypic identification and detection of mixed infection of Beijing and non-Beijing strains in Pakistan and its prevalence in new and retreatment cases on the basis of deleted and intact genetic regions in Beijing and Non-Beijing strains of M. tuberculosis respectively
Summary
Tuberculosis (TB) continues as one of the deadliest contagious diseases across the globe. 9 million people developed TB in 2013 and the year ended with the demise of 1.5 million people due to TB. Of the total TB cases and deaths, around 56.25 % are men but the burden of the disease is eminent in women as well. Out of the total TB cases occurred in 2014, 58 % belonged to the South-east Asian and Western Pacific regions (WHO 2015). 420,000 cases occur each year out of 9000 cases are of DRTB. Socio-economic conditions are greatly influenced by TB as 75 % of cases are among the dynamic (15–45) age group (Programme NTC 2012). TB is closely associated to poverty and social deprivation (Lonnroth et al 2009). Poor living conditions like overcrowding, poor ventilation, close proximity and malnutrition are the major risk factors for
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