DOTS (directly observed treatment, short-course), is the name given to the tuberculosis control strategy

recommended by the World Health Organization.[1] According to WHO, “The most cost-effective way to

stop the spread of TB in communities with a high incidence is by curing it. The best curative method for

TB is known as DOTS.”[2] DOTS has five main components:

Government commitment (including political will at all levels, and establishment of a centralized

and prioritized system of TB monitoring, recording and training).

Case detection by sputum smear microscopy.

Standardized treatment regimen directly of six to eight months observed by a healthcare worker

or community health worker for at least the first two months.

A drug supply.

A standardized recording and reporting system that allows assessment of treatment results.

Tuberculosis can affect many areas of the body, but it most commonly causes disease in the lungs. The American Thoracic Society, in conjunction with the Centers for Disease Control and Prevention and the Infectious Disease Society of America, has formulated a classification system for TB to help guide treatment of the disease and provide an operational framework for public health agencies. This system uses 6 categories of pulmonary TB -- 0 through 5. Class 0 indicates individuals who are not infected. People in this group have had no exposure to TB, and their tuberculin skin test results, if done, are negative.

Exposure but No Evidence of Infection People in class 1 have been exposed to TB, but their subsequent tuberculin skin test results are negative. The follow-up course of action for people in this category depends on several factors, including how recent and extensive the exposure was and the overall health of the individual. Significant exposure within the past 3 months warrants a follow-up skin test at about 10 weeks after exposure. Sometimes, treatment is started while waiting for the skin test results, particularly in individuals with HIV or young children.

Latent Infection but No Disease Class 2 identifies those people who have a positive reaction to the tuberculin skin test but no symptoms or other evidence of TB on a chest x-ray or additional testing. People in this category do not feel sick and cannot spread the disease at this stage, but if left untreated, latent TB has the potential to develop into active disease, or class 3 TB. Recommended treatment varies depending on a number of factors. For example, people with HIV and infants and children less than 5 have an increased risk of developing class 3 TB, so they may warrant additional or longer treatment regimens.

Active Tuberculosis Class 3 includes anyone with active TB based on the presence of symptoms or positive laboratory testing. Typical symptoms include a persistent cough that may produce blood or mucus, fever, chills, night sweats, pain in the chest, loss of appetite, weight loss and weakness. A diagnosis of active TB can be confirmed via a number of lab tests, the most important of which is identifying the presence of Mycobacterium tuberculosis -- the bacteria that causes TB -- in the body. The most common way to diagnose active pulmonary TB is by finding the bacteria in a sample of sputum.

Inactive or Suspected Tuberculosis Class 4 TB identifies people who had active TB in the past but no longer show any evidence of active disease. Their skin tests are positive and chest x-rays may be abnormal, but they have no symptoms and their lab tests are negative. Class 5 includes those individuals who are suspected of having TB but are still waiting for test results to confirm whether they have the disease. Some people in class 5 may already be receiving treatment while they wait for the final test results. Once all test results are completed, the individual will be moved to the most appropriate class.

TB drugs – the basic drugs The five basic or “first line” TB drugs are:2 Isoniazid Rifampicin Pyrazinamide

Ethambutol and Streptomycin These are the TB drugs that generally have the greatest activity against TB

bacteria and they are core to any TB drug treatment program. These TB drugs are particularly used for

someone with active TB disease who has not had TB drug treatment before.

All the other TB drugs are generally referred to as “second line” or reserve TB drugs.

TB drug treatment for new patients New patients are those who have either not had any TB treatment

before, or they have only had less than one month of anti TB drugs. New patients are presumed to have

drug susceptible TB (i.e. TB which is not resistant to any of the drugs) unless there is a high level of

isoniazid resistance in new patients in the area, or the patient has developed active TB disease after they

have had contact with a patient who is known to have drug resistant TB.

For these patients the World Health Organisation (WHO) recommends that they should have six months

of TB drug treatment. This should consist of a two month “intensive” treatment phase followed by a four

month “continuation” phase.

For the two month “intensive” TB drug treatment phase they should receive:

Isoniazid with rifampicin and pyrazinamide and ethambutol followed by

Isoniazid with rifampicin for the “continuation” TB drug treatment phase.

It is essential to take several TB drugs together. If only one TB drug is taken on its own, then the patient

will very quickly become resistant to that drug.

It is recommended that patients take the TB drugs every day for the six months, although taking them

three times a week is possible in some circumstances. It is extremely important that all the recommended

TB drugs are taken for the entire time.

If only one or two of the TB drugs are taken, or the treatment is interrupted or stopped early, then the

treatment probably won’t work, because the TB bacteria that a patient has develops resistance to the TB

drugs. Not only is the patient then still ill, but to be cured they then have to take drugs for the treatment of

drug resistant TB, and these drugs are more expensive and have more side effects.

TB drugs for the treatment of drug resistant TB For the treatment of drug resistant TB, the current TB

drugs are grouped according their effectiveness, experience of use, and drug class, as shown below.

All the first line TB drugs are in Group or class 1, apart from streptomycin which is with the other

injectable agents in Group 2. All the drugs in Groups 2 to 5, apart from streptomycin, are referred to as

“second line” or reserve TB drugs.3 The first four groups of TB drugs listed below, are those that are

mainly used for the treatment of drug resistant TB. The fifth group of TB drugs are some drugs that are

unknown in how effective they are in the treatment of TB, but they can be tried when there is no other

option, such as in the treatment of totally drug resistant TB.

TB drugs used to treat drug resistant TB according to group (class)

Group 1 TB drugs : First Line Oral Agents

pyrazinamide

ethambutol

rifabutin

Group 2 TB drugs : Injectable Agents

kanamycin

amikacin

capreomycin

streptomycin

Group 3 TB drugs : Fluoroquinolones

levofloxacin

moxifloxacin

ofloxacin

Group 4 TB drugs : Oral Bacteriostatic Second Line Agents

para–aminosalicylic acid

cycloserine

terizidone

thionamide

protionamide

Group 5 TB drugs: Agents with an unclear role in the treatment of drug resistant TB

clofazimine

linezolid

amoxicillin/clavulanate

thioacetazone

imipenem/cilastatin

high dose isoniazid

clarithromycin

Very few actual trials have been carried out of the drugs in Group 5 to see how effective they actually are

in the treatment of drug resistant TB. For example, the drug linezolid is an antibiotic usually used to treat

severe bacterial infections. The first trial has just been carried out of this drug looking at the use of it in

treating XDR-TB. It was a small trial but it did show that the drug was effective when added to patients

current treatments, although most of the patients experienced side effects.4