Overview of Drug Resistant Mycobacterium tuberculosis

Abstract

MDR-TB is a global occurrence that poses a serious threat. Tuberculosis (TB) is still the leading cause of death from a single and curable infectious disease. It is the second-most common cause of death from infectious disease (after those due to HIV/AIDS). Its situation is worsened by the presence of multidrug-resistant (MDR) strains of M. tuberculosis. In ancient time, it was considered a curse. Tuberculosis started to reemerge in the early 1990s. The completion of the first whole genome sequence of M. tuberculosis was in 1998. Multi drug resistant (MDR)-TB is caused by strains of M. tuberculosis that resistant to at least rifampicin and isoniazid. Worldwide India is the country with the highest-burden of both TB and MDR-TB. Isolation of MTB on solid media followed by subsequent DST on solid media is easy to perform in the lab. They are time-consuming classical laboratory tests methods. So the molecular method is preferable to detect MTB. Different types of tool are available to detect MDR-TB, XDR-TB. Now-a-days, there are three major commercial alternatives available and they are: GeneXpert, line probe assays (LPA) and Nucleic acid amplification tests (NAAT). The treatment takes too long, many patients are unable to tolerate the combination, and there is a growing threat from multidrug-resistant (MDR) and extremely drug-resistant (XDR)-TB. Reliable and timely detection of drugresistant TB is needed. Key-words: Tuberculosis (TB), Mycobacterium tuberculosis (MTB), Mycobacterium tuberculosis complex (MTBC), Multidrug resistant (MDR), Extensively drug resistant (XDR), Extra pulmonary tuberculosis (EPTB), Nucleic acid amplification tests (NAAT) INTRODUCTION M. tuberculosis is the etiologic agent of tuberculosis (TB), a potentially fatal illness which results in approximately 2 million deaths worldwide each year . Tuberculosis is the second-most common cause of death from infectious disease (after those due to HIV/AIDS) . Tuberculosis (TB) is still the leading cause of death from a single and curable infectious disease. In 2012, 8.6 million incident new and relapse cases of active TB disease occurred with an estimated 1.1 million (13%) of incident TB-HIV co-infected patients. The majority of TB cases worldwide were in the South-East Asia (29%), African (27%) and Western Pacific (19%) regions. India and China alone accounted for 26% and 12% of total cases, respectively . According to WHO, in 2016 an estimated 28 lakh cases occurred and 4.5 lakh people died due to TB disease . How to cite this article Rai A, Khan T. Overview of Drug Resistant Mycobacterium tuberculosis. Int. J. Life Sci. Scienti. Res., 2018; 4(3): 1795-1800 Access this article online www.ijlssr.com MDR-TB is a global occurrence that poses a serious threat to ongoing national TB control programmes. Multidrug-resistant tuberculosis (MDR-TB) is caused by a strain of M. tuberculosis that is resistant to at both isoniazid (INH, H) and rifampicin (RMP, R) that are two most powerful 1 line anti TB drugs. According to the 2017 World Health Organization global report, approximately 490000 people were infected by MDR-TB. In addition, there were an estimated 110,000 people who had rifampicin resistant TB (RR-TB). So the number of people estimated to have had MDR-TB or RR-TB in 2016 was 600,000 with approximately 240,000 deaths. [5] Generally TB affects the lungs, but other parts of the body can also be affected . The true sign of active TB is a long term cough with blood-containing sputum, night sweats, and weight loss . There are two types of clinical manifestation of tuberculosis (TB) includes pulmonary TB (PTB) and extra-pulmonary TB (EPTB). EPTB is the TB involving organs other than the lungs (e.g., pleura, lymph nodes, abdomen, genitourinary tract, skin, joints and bones, or meninges). Involvement of Extra pulmonary can occur in isolation or along with a pulmonary focus as in the case of patients with disseminated tuberculosis Review Article Copyright © 2015 2018| IJLSSR by Society for Scientific Research under a CC BY-NC 4.0 International License Volume 04 | Issue 03 | Page 1795 Int. J. Life Sci. Scienti. Res. eISSN: 2455-1716 Rai and Khan, 2018 DOI:10.21276/ijlssr.2018.4.3.9 (TB). The recent human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) pandemic has resulted in changing epidemiology and has once again brought extra pulmonary tuberculosis (EPTB) into focus . Here, I reviewed some of the insights into the evolutionary history of the tuberculosis disease. HistoryPrior to the twentieth century, tuberculosis as a disease was considered to be of little importance to the general population in India . In ancient time, it was considered as curse. TB in India is an ancient disease, and in Indian literature there are passages from around 1500 BCE in which consumption is mentioned, and the disease is attributed to excessive fatigue, worries, hunger, pregnancy and chest wounds . TB started to reemerge in the early 1990s, fuelled by the growing pandemic of HIV/AIDS . According to other dogmas, TB was mainly a consequence of reactivation of latent infections rather than ongoing disease transmission, and that mixed infections and exogenous reinfections with different strains were very unlikely. TB is caused by several species of gram-positive bacteria known as tubercle bacilli or M. tuberculosis complex (MTBC). MTBC includes obligate human pathogens such as M. tuberculosis and M. africanum as well as organisms adapted to various other species of mammal. In the developed world, TB incidence declined steadily during the second half of the 20 century and so funds available for research and control of TB decreased substantially during that time . Robert Koch discovered the causal agent M. tuberculosis, and was awarded by Nobel Prize in physiology/medicine in 1905 . Over a long period of time multiple antibiotics required for TB treatment. After the Second World War the first anti-tuberculosis drugs were introduced and then more effective drugs following in early 1950 . The completion of the first whole genome sequence of M. tuberculosis was in 1998 . Studies have shown that humans did not, as previously believed, acquire MTBC from animals during the initiation of animal domestication, rather the human and animal-adapted members of MTBC share a common ancestor, which might have infected humans even before the Neolithic transition . Drug Resistant TuberculosisTuberculosis (TB) is a serious public health problem worldwide. Its situation is worsened by the presence of multidrug resistant (MDR) strains of M. tuberculosis. In recent years, even more serious forms of drug resistance have been reported. Multi drug resistant (MDR)-TB is caused by strains of M. tuberculosis that are resistant to at least rifampicin and isoniazid two key drugs in the treatment of the disease. It has been recognized the presence of even more resistant strains of M. tuberculosis labeled as extensively drug resistant (XDR)-TB. These strains in addition to being MDR are also resistant to any fluoroquinolone and to at least one of the injectable second-line drugs: kanamycin, capreomycin or amikacin. More recently, a more worrying situation has emerged with the description of M. tuberculosis strains that have been found resistant to all antibiotics that were available for testing, a situation labeled as totally drug resistant (TDR)-TB. MDR tuberculosis among household contacts is also reported from several studies. In a study, which was done in northern India and reported 11(2.57%) contacts developed MDR-TB while 4(0.93%) cases developed drug susceptible TB subsequent out of total 428 contacts of the index patient. The Overall rate of disease in the present study was 3.50 % . According to Global tuberculosis controlsurveillance, planning, financing in 2008 “Tuberculosis continues to be a leading cause of mortality and morbidity worldwide .” According to WHO/IUATLD Global Project on Antituberculosis Drug Resistance Surveillance “The emergence and spread of MDR-TB is threatening to destabilize global tuberculosis control. The prevalence of MDR-TB is increasing throughout the world both among new tuberculosis cases as well as among previously treated ones .” WHO reported in 2016 that India has a high burden of MDR-TB and also mentioned that the MDR-TB amongst notified new pulmonary TB patients was 2.8%, whereas amongst notified re-treatment pulmonary TB patients, it was 12% . According to "Global Tuberculosis Control 2016", rates per 100,000 people in different areas of the world are: globally 140, Africa 254, the Americas 27, Eastern Mediterranean 114, Europe 32, Southeast Asia 240, and Western Pacific 95 in 2015. According to the latest World Health Organization (WHO) report, there were an estimated 10.4 million incident cases of TB in 2016 and 1.7 million deaths were attributed to the disease. 250,000 cases occurred in children and 0.4 million deaths were reported among HIV-infected persons. Copyright © 2015 2018| IJLSSR by Society for Scientific Research under a CC BY-NC 4.0 International License Volume 04 | Issue 03 | Page 1796 Int. J. Life Sci. Scienti. Res. eISSN: 2455-1716 Rai and Khan, 2018 DOI:10.21276/ijlssr.2018.4.3.9 The latest Global Tuberculosis Report estimates that 4.1% of new and 19% of previously treated tuberculosis (TB) cases diagnosed in 2015 were multidrug-resistant (MDR). India accounts for one-fourth of the global TB burden. In 2015, an estimated 28 lakh cases occurred and 4.8 lakh people died due to TB. India has the highest burden of both TB and MDR TB based on estimates reported in Global TB Report 2016. An estimated 1.3 lakh incident multi-drug resistant TB patients emerge annually in India which includes 79000 MDR-TB Patients estimates among notified pulmonary cases. The incidence of TB is 217 per lakh per year in 2015 and the mortality due to TB is 36 per lac per year in 2015 . Worldwide India is the country with the highest burden of both TB