Tuberculosis treatment therapy may be started before microbiological confirmation of TB for the following reasons:
The subjective and objective findings are fairly convincing.
Active TB is contagious.
The likelihood of drug resistance emerging is reduced when treatment is initiated early.
The ill effects of treatment if the diagnosis is wrong do not outweigh the benefits of treating an unconfirmed, but infected patient.
The Stages of TB Therapy and the Drugs Used During the Course of Tuberculosis Treatment
Mycobacteria are aerobic, gram negative, AFB, which occur in two forms, a slow growing (dividing) intracellular form, which can persist in macrophages or healed TB foci for years, and a fast growing (dividing) extracellular form.
The goal of treatment of active TB is to eradicate the mycobacteria with an initial phase of therapy (2 months) for rapid growing organisms (to make patient non-contagious), and a continuation phase (4 months) to eradicate the slow growing, persistent organisms.
A combination of first line drugs, isoniazid (INH), rifampin (RIF), pyrazinamide (PZA), and ethambutol (EMB), are used in patients with suspected drug-susceptible, non-resistant organisms. INH and RIF are given for 6 months (the initial phase for the first 2 months and then the continuation phase for the last 4 months). PZA and EMB are given for the first 2 months (the initial phase of treatment).
In a patient who has a cavity on chest x-ray taken from before treatment was begun and who has a positive TB culture after 2 months of therapy (the end of the initial phase of treatment), the usual 6 month therapy regimen should be extended for 2 more months for a total of 8 months in order to prevent a relapse of the patient’s TB.
When resistant TB organisms are present (as may be seen in HIV infected patients and in immigrants from Haiti, Mexico, sub-Saharan Africa, South Asia, and the developing nations of East Asia and the Pacific) treatment must be administered based on probable resistances until sensitivity studies are completed.
In patients with suspected drug-sensitive organisms, once treatment is begun, spread and contagion are very low as evidenced by the present treatment of these patients in an outpatient (home) setting if they are considered reliable and will cover their mouths when coughing. Once coughing ceases, spread of TB is very unlikely as evidenced by many years of this method of treatment in the United States with almost no incidence of TB in the household of these patients. The key to successful treatment of TB is that the patient takes the medication properly. Adherence is crucial to success.
Acid-fast (AFB) smears usually become negative before TB cultures become negative in patients receiving TB therapy. Finally, before TB medications are stopped, AFB smears and cultures should be negative and chest x-ray improvement must occur.
Surgical Therapy Used in Tuberculosis Treatment
At times the bacillary populations of TB are so large and so resistant that in order to treat the active TB effectively removal of part of the lung is necessary. This requires consultation with experts in the field of TB treatment and should not be undertaken arbitrarily.