What
is MDR tuberculosis?
Multidrug
resistance TB is caused by TB bacteria that are resistance to at least isoniazid
and rifampicin, the two most potent TB drugs.
Some
strains of the TB bacteria developed resistance to the standard drugs through
genetic changes. Currently the majority of the multidrug resistance cases of TB
are due to one strain of TB bacteria called the Beijing Lineage.
This process
accelerates if incorrect treatment are used, leading to the development and spread
of multidrug resistance.
Mechanism
of Drug resistance in TB patients
Resistance
to rifampicin in M. tuberculosis
have been found to be due to mutation in rpoB of RNA polymerase retarding
affinity for rifampicin. Most of the rifampicin resistant isolates, have a
missense mutation and substitution of nucleotide at codon 56 and 531 of rpoB,
was also able to identify resistant strains with a form of mutation at 69-bp
region and point mutation in rpoB alleles.
The mode
of action of Isoniazid resistance is complex and remains unclear, however,
most isoniazid MTB-resistance strains have been associated with mutation in KatG
and inhA. Mutations of the S315T KatG is more common in
isoniazid resistant strains.
Risk
factors
More common
in people who:
· Do
not take their TB medicine regularly
·
Do
not take all of their TB medicine as told by their doctor
·
Develop
TB disease again, after having taken TB medicine in the past
·
Come
from area of the world where drug resistance TB is common
· Contact with the MDR TB patient
How
many people have it?
There
were an estimated 484,000 incident cases in 2018. Half of these cases
were in India (27%), China (14%) and the Russian Federation (9%). There is
more about TB in India.
In 2018 an estimated 3.4% of new cases and 18%
of previously treated cases had MDR/RR-TB.
Can
MDR TB cause people to die?
In 2018
MDR TB and RR TB caused approximately 214,000 deaths.
MDR
TB prevention
The most
important thing a person can do to prevent the spread of NDR TB is to take all
of their medications exactly as prescribed by their health care provider. No
doses should be missed and treatment should be missed and treatment should not
be stopped early.
Health
care providers can help prevent MDR TB quickly diagnosis cases, following recommended
treatment guidelines, monitoring patients response to treatment, and making
sure therapy is completed.
Another
way to prevent getting MDR TB is to avoid exposure to known MDR TB patients in
closed such as hospitals, prisons, or homeless shelters.
Treatment
of MDR patient
Fluoroquinolones
are the drug of choice in case of MDR TB. Levofloxacin and Moxifloxacin are the
useful drugs.
WHO
drug resistance TB guidelines 2022: what is new?
The new
WHO 2022 guidelines evaluated the following new regimens:
1.
The
6 month regimen based on bedaquiline,
pretomanid and linezolid (BPaL) in combination with moxifloxacin (BPaLM),
evaluated in the TB-PRACTECAL randomized clinical trial:
2.
The
6 month regimens based on the BPaL combination with decreased exposure to
linezolid evaluated in the ZeNix study.
3.
The
modified all oral shorter regimens containing all three group A drugs evaluated
in the NeXT trial using programmatic use of all oral treatment shorter or
longer regimens.
