Sjh standardized diagnostic categories

Based on case definition, all TB patients (adults and children) fall into one of four diagnostic categories for treatment. Patients are categorized in order to match each diagnostic category with an effective treatment regimen.The table below shows the patients belonging to each category.

TB diagnostic category


Category I

° new sputum smear-positive PTB ° new sputum smear-negative PTB with extensive parenchymal involvement ° new cases of extrapulmonary TB (more severe forms)

° severely ill TB patients with concomitant HIV infection

Category II

° previously treated sputum smear-positive PTB: relapse, treatment after default, treatment after failure

Category III

° new sputum smear-negative PTB with limited parenchymal involvement and known HIV-negative

° extrapulmonary TB (less severe forms) and known HIV-negative

Category IV

° chronic and MDR-TB cases

The table below shows the severe and less severe forms of extrapulmonary TB.

Severe extrapulmonary TB

Less severe extrapulmonary TB


lymph node


pleural effusion (unilateral)


bone (excluding spine)


peripheral joint

bilateral or extensive pleural effusion

adrenal gland




Children often fall into Category III. PTB in children is almost always "smear-negative" (actually a smear is often not done, since children rarely cough up sputum).Young people infected during adolescence may develop primary TB. This usually presents as pleural effusion or small parenchymal lesions in the lungs. In one series of adolescents with pleural effusion, without treatment about 25% went on to develop PTB.

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