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Tuberculosis (Mycobacterium tuberculosis)
1996 Case Definition
Clinical description
A chronic bacterial infection caused by Mycobacterium
tuberculosis, characterized pathologically by the formation
of granulomas. The most common site of infection is the lung,
but other organs may be involved.
Clinical case definition
A case that meets the following criteria:
- A positive tuberculin skin test
- Other signs and symptoms compatible with tuberculosis
(e.g., an abnormal, unstable [i.e., worsening or improving]
chest radiographs, or clinical evidence of current disease)
- Treatment with two or more antituberculosis
medications
- Completed diagnostic evaluation
Laboratory criteria for diagnosis
- Isolation of M. tuberculosis from
a clinical specimen* or
- Demonstration of M. tuberculosis from
a clinical specimen by nucleic acid amplification test,** or
- Demonstration of acid-fast bacilli in a clinical
specimen when a culture has not been or cannot be obtained
Case classification
Confirmed: a case
that meets the clinical case definition or is laboratory confirmed
Comment
A case should not be counted twice within any consecutive
12-month period. However, cases in which the patients had previously
had verified disease should be reported again if the patients
were discharged from treatment. Cases also should be reported
again if patients were lost to supervision for greater than 12
months and disease can be verified again. Mycobacterial diseases
other than those caused by M. tuberculosis complex should
not be counted in tuberculosis morbidity statistics unless there
is concurrent tuberculosis.
*Use of rapid identification techniques for M. tuberculosis
(e.g., DNA probes and mycolic acids high-pressure liquid chromatography
performed on a culture from a clinical specimen) are acceptable under
this criterion. **Nucleic acid amplification
(NAA) tests must be accompanied by culture for mycobacteria species.
However, for surveillance purposes, CDC will accept results obtained
from NAA tests approved by the Food and Drug Administration (FDA)
and used according to the approved product labeling on the package
insert. Current FDA-approved NAA tests are only approved for smear-positive
respiratory specimens.
See also:
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