Drug resistance in TB remains a man-made phenomenon. It emerges as a result of spontaneous gene mutations in M. tuberculosis that render the bacteria resistant to the most commonly used anti-TB drugs. Among the reasons for this, the non-compliance with the treatment regimens is signaled as the first cause.
Multidrug-resistant TB (MDR TB) is caused by an organism that is resistant to at least isoniazid and rifampin, the two most potent TB drugs. These drugs are used to treat all persons with TB disease.
Drug resistance is a formidable obstacle to TB care and prevention globally, making it harder and longer to treat, often with poorer outcomes for patients. People with drug-resistant TB face significant economic and social costs and only 1 in 3 access quality care.
Regimens for the treatment of TB disease must contain multiple drugs to which the bacteria are susceptible. The standard of care for initiating treatment of TB disease is four-drug therapy. Treatment with a single drug can lead to the development of a bacterial population resistant to that drug.
Table 3Pattern of Drug ResistanceSuggested RegimenMinimum Duration of Treatment (mo)Rifampin and ethambutol (±streptomycin)Isoniazid, pyrazinamide, fluoroquinolone, plus an injectable agent for at least the first 2–3 mo Or a fully oral MDR-TB regimen per WHO guidelines187 more rows
Resistance to anti-TB drugs is caused mainly by mutations in drug target genes [4], the impermeability of M. tuberculosis cell wall, and the activity of efflux pumps [5, 6]. The presence of mutations in the target genes of antibiotics is considered the most important resistance mechanism in this bacterium [7].May 2, 2019
β-lactam antibiotics bind and inhibit the activities of penicillin-binding proteins involved in cell wall biosynthesis, but mycobacteria possess β-lactamase enzymes that degrade these drugs. This is the main mechanism conferring resistance to β-lactam antibiotics.May 9, 2011
New evidence on the effectiveness and safety of all-oral shorter regimens for MDR/RR-TB treatment was made available to WHO during 2019, specifical...
The Rapid Communication was released by WHO in advance of the detailed updated policy guidelines to alert national TB programmes and other stakehol...
The most important changes signalled by the Rapid Communication are the following: Injectable medicines should be phased out as a matter of priorit...
In the evidence provided by South Africa that supported the decision by the GDG, treatment regimen contained bedaquiline for 6 months, plus levoflo...
All MDR/RR-TB patients in whom resistance to fluoroquinolones was ruled out and without: Confirmed resistance to or suspected ineffectiveness of a...
Yes. The data from South Africa used for the analysis included a high proportion of HIV co-infected patients (71%).
No. The shorter all-oral bedaquiline containing regimen was implemented as a standardized package under programmatic conditions in South Africa. Th...
Yes, in children older than six years, as no evidence is available for the use of bedaquiline in children under 6 years of age. Pediatric dosing of...
Yes. The use of bedaquiline as a part of an all-oral longer MDR-TB regimen was shown to be generally safe in pregnant women in a study in South Afr...
WHO consolidated guideline on drug-resistant tuberculosis treatment. (WHO/CDS/TB/2019.4). Geneva, World Health Organization, 2019
We would like to thank the colleagues from the Global Fund to Fight AIDS, Tuberculosis and Malaria, United States Agency for International Development and the Global Drug Facility of the Stop TB Partnership for their comments and contribution to the FAQs.
First-line essential anti-tuberculosis agents are the most effective, and are a necessary component of any short-course therapeutic regimen. The drugs in this category are isoniazid, rifampin, ethambutol, pyrazinamide and streptomycin. Second-line anti-tuberculosis drugs are clinically much less effective than first-line agents ...
Multidrug-resistant tuberculosis (MDR-TB), caused by tubercle bacilli that are resistant to at least isoniazid and rifampin, is among the most worrisome elements of the pandemic of antibiotic resistance because TB patients for whom treatment has failed have a high risk of death. Drugs used to treat tuberculosis are classified into first-line ...
New drugs, which are yet to be assigned to the above categories, include rifapentine, levofloxacin, gatifloxacin and moxifloxacin. Recently there has been much development in the molecular pharmacology of anti-tuberculosis drugs.
Molecular assays for identification of drug resistancecan hasten the time from weeks to 1-2 days to identify the presence of drug resistance. All molecular assays detect mutations in mycobacterial DNA that are known to cause resistance to a specific anti-TB drug.
The diagnosis of tuberculosis (TB) frequently requires a high index of suspicion, especially in low-prevalence areas. The index of suspicion should be based on consideration of clinical and epidemiological risk factors, symptoms, physical examination findings (e.g., enlarged lymph nodes or other findings suggestive of possible extra-pulmonary ...
In such instances, the resistant and susceptible pop- ulations are part of the same strain and therefore, have the same genotype. However, the drug-resistant bacteria will have acquired mutations that confer drug resistance. Reinfection with a resistant strain is likely to demonstrate a dif- ferent genotype. Summary.
Treatment can take up to two years, cure rates are lower and fatalities are higher. In poorer countries, it can be very difficult to treat MDR-TB. Treatment options are limited and expensive, the best medicines may not be available, and patients can experience many bad side effects from the drugs.
Drug-resistant forms of TB can develop if treatment is incorrect or incomplete. This can happen for several reasons. Because treatment for TB takes six months and can have difficult side effects, people may be tempted to stop taking their medication before they have completed treatment, particularly if they are starting to feel better. ...
Multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB) are major global health threats. WHO estimates that 480,000 people developed MDR-TB in 2015, but only 52% of cases were identified and treated appropriately.
They may be given the incorrect treatment or may fear the stigma of having TB. People with infectious drug-resistant TB can then also pass this drug-resistant strain on to others.