Study of the resistance of Mycobacterium tuberculosis to the principal tuberculostatics (Hospital of Navarra 1996-2003)

Abstract

Introduction. The aim of this study was to evaluate the sensitivity to the principal tuberculostatics of the M. tuberculosis stocks isolated in our laboratory and to study the factors related to resistance. Methods. Study of 475 stocks of M. tuberculosis corresponding to all cases diagnosed in the eight year period between 1996 and 2003. We employed the BACTEC 460TB system, together with Lowenstein solid medium, in the cultivation of the samples. The sensitivity studies were carried out using the BACTEC 460TB system. Results and conclusions. Both the incidence and the number of cases of resistant tuberculosis showed oscillations over the eight years of the study. The fact that there is no homogeneous tendency makes it necessary to maintain active surveillance of this process. Global resistance to isoniacide was 8%, making it is convenient to carry out sensitivity studies in all the diagnosed cases. The cases of multiresistant tuberculosis (resistant to at least isoniacide and rifampicin), did not exceed 3%. The prognosis of the patients with resistant tuberculosis was bleak in cases of coinfection with HIV; however, when the immunological defences were conserved, and guidelines for treatment with active drugs were provided, the recovery of the majority of the patients was achieved. At present, sensitive and rapid procedures are available to us, making it recommendable to study the sensitivity of all the stocks of M. tuberculosis that are isolated; this is essential in the case of HIV positive or immigrant patients.