Mycobacterium
tuberculosis is a very slow-growing organism that requires the use of
multiple drugs for several months for treatment. With the appropriate
antibiotics tuberculosis can be cured in most individuals. Treatment usually
combines several different antibiotic drugs that are given for at least 6
months and sometimes for as long as 12 months. However, many M. tuberculosis strains are resistant to
one or more of the standard TB drugs, which complicates treatment greatly.
Currently, there are 10 drugs approved by the U.S. Food and
Drug Administration for the treatment of TB. Of the approved drugs, isoniazid,
rifampin, ethambutol, and pyrazinamide are considered first-line
antituberculosis agents. These four drugs form the foundation of initial
courses of therapy.
Drug-resistant TB is major problem for the treatment of the disease.
Multidrug-resistant TB, is defined as disease caused by TB bacilli resistant to
at least isoniazid and rifampicin, the two most powerful anti-TB drugs. Mulitdrug-resistant
tuberculosis is resistant to drugs but its resistance can be intensified by
inconsistent or partial treatment. When patients do not take all their
medication regularly for the required time period, drug-resistant bacteria can
arise. While drug-resistant TB is generally treatable, it requires extensive
chemotherapy with second-line anti-TB drugs. These second line drugs produce
more severe adverse drug reactions more frequently than the preferred first
line drugs. There are six classes of second-line drugs used for the treatment
of TB including aminoglycosides, fluoroquinolones, polypeptides, thioamides, cycloserine,
and p-aminosalicylic acid.
Within the last few years a new form of TB has emerged,
extensively drug-resistant TB. Whereas regular TB and even multidrug-resistant TB
progress relatively slowly, extensively drug-resistant TB progresses much more
rapidly and can be fatal within months or even a few weeks. Extensively
drug-resistant TB is defined as TB that has developed resistance to at least
rifampin and isoniazid, as well as to any member of the fluoroquinolone family
and at least one of the aminoglycosides or polypeptides. The emergence of
extensively drug-resistant TB, particularly in settings where many TB patients
are also infected with HIV, poses a serious threat to TB control.
Currently, short course Direct Observation Therapy (DOTS) is
a key component of the World Health Organization's campaign to stop TB. DOTS
involves patient case management by trained health professionals who ensure that
the patient is taking their TB drugs. Because TB has such a long course of
treatment, many patients stop their medications prematurely. DOTS sends health
professionals to the patient to ensure they are taking the medication and may
also supply the medicine to the patient. In some areas, patients come to the
DOT clinic instead of the health worker traveling to them. Often, DOTS provides
enablers or incentives to ensure patients continue their treatment, such as
transportation or free meals.
This is very interesting I had no idea that there were different forms of TB with different levels of resistance. It's weird that the extensive drug resistant TB is so much worse than the other forms with a faster progression and higher fatality so what is it about the higher level of resistance that makes it so much worse on a the body. Are these resistances based off of its resistance to the drugs at a certain dosage and could it be beneficial to develop stronger doses of these drugs to possibly bypass the resistance or could this be dangerous in the possibility of it merely strengthening the already resistant strands.
ReplyDeleteThere was a recent report of a Subway employee in Tuscaloosa that had TB. The health department began to do an investigation. The ADPH says they are working closely with the restaurant to get employees screened. Only those people who were in close contact with the case needed to be tested. Patrons of the restaurant were not recommended to be tested because TB can not be trasmitted through the food or utensils. I personally never eat at this particular subway because there's one closer to my house. However I still would think that they would want the people who regularly eat there be tested for the simple fact that TB is spread through inhalation of air droplets from a cough or sneeze of an infected person. So anyone in and out of the Subway could have easily been exposed. I guess the Health Department didn't see this as a big issue.
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