MPB64 mycobacterial antigen: a new skin-test reagent through patch method for rapid diagnosis of active tuberculosis.

SETTING

A collaborative study between the Japan BCG Laboratory, Tokyo, Japan, and the Infectious Disease Section, Philippine General Hospital, Manila, the Philippines. Tuberculosis patients from four clinics in the vicinity of Manila, Our Lady of Grace Parish, Sto. Niño de Tondo Parish, the Canossa Health and Social Center, and the Health Care Development Center, were examined.

OBJECTIVE

To develop a new, simple and rapid diagnostic method for active tuberculosis. Subjects were tested for skin reaction to a special antigen, MPB64, by the patch test method instead of intradermal injection of purified protein derivative (PPD).

DESIGN

Fifty-three active tuberculosis patients and 43 healthy PPD-positive controls were tested to determine whether or not the reaction to MPB64 was positive only in active tuberculosis patients.

RESULTS

Fifty-two of the 53 active tuberculosis patients showed a positive reaction to MPB64, while none of the 43 PPD-positive controls did. The specificity of MPB64 to active tuberculosis was 100%, and the sensitivity was 98.1%. The efficacy of the test was 98.9%.

CONCLUSION

The patch test with MPB64 is a promising method for the diagnosis of active tuberculosis, distinguishing tuberculous patients from those who are infected but have not developed the disease, and also from BCG-vaccinated individuals. This new skin test is a subject for further evaluation and it is important to compare the results with PPD Mantoux.