Is it necessary to add a fourth drug to the initial treatment of tuberculosis? (multiple letters)

1. Vidal, R.
2. Miravitlles, M.
3. Torres, L.
4. Pérez, J.B.
5. Leczano, M.A.
6. Revillo, M.J.
7. Casabona, N.M.
8. Caylà, J.A.