Core Curriculum on Tuberculosis, 2000
Treatment of TB Disease
Response to Treatment
For patients whose sputum cultures are positive
before treatment, the best way to measure the effectiveness of therapy
is to obtain specimens for culture at least monthly until the cultures
convert to negative. Patients whose sputum no longer contains M.
tuberculosis after 2 months of treatment should have at least
one further sputum smear and culture performed at the completion
of therapy. Patients with multidrug-resistant TB should have cultures
performed monthly for the entire course of treatment. Radiographic
evaluations during treatment are of less importance than sputum
evaluation. However, a chest film at completion of treatment provides
a baseline for comparison with any future films.
Patients whose cultures have not become negative or whose symptoms
do not resolve despite 3 months of therapy should be reevaluated
for potential drug-resistant disease, as well as for potential failure
to adhere to the regimen. If the patient is receiving self-administered
therapy, the remainder of treatment should be directly observed.
While the results of drug susceptibility testing are pending, the
original drug regimen may be continued or may be augmented by at
least two drugs not given previously. Never add one drug at a
time to a failing regimen; this may cause further drug resistance.
If drug susceptibility results show resistance to any of the first-line
drugs or if the patient remains symptomatic or smear or culture
positive after 3 months, a TB medical expert should be consulted.
In patients with negative sputum cultures before treatment, the
major indicators of response to therapy are the chest radiograph
and the clinical evaluation. The intervals at which chest radiography
should be repeated depend on the clinical circumstances and the
differential diagnosis that is being considered, but usually no
more than every 3 months. If the radiograph does not improve after
the patient has received 3 months of treatment, the abnormality
may be the result of either previous (not current) TB or another
Routine follow-up after therapy is not necessary for patients who
have had a satisfactory and prompt bacteriologic response to 6-
or 9-month therapy with both isoniazid and rifampin. Patients whose
organisms were fully susceptible to the drugs being used should
be instructed to promptly report the development of any symptoms,
particularly prolonged cough, fever, or weight loss. For patients
with organisms resistant to isoniazid or rifampin or both, follow-up
evaluation must be individualized.