[Primary resistance of Mycobacterium tuberculosis in 10 hospitals of the community of Castille and Leon. Group of Microbiologists from Castille and Leon].

OBJECTIVE

To determine the primary drug resistance (PDR) of Mycobacterium tuberculosis in ten hospitals in the Castile-León Community for a five-year period (1991-1995), in a sanitary area with almost two millions of inhabitants.

MATERIAL AND

METHODS

The sensitivity of 825 strains of Mycobacterium tuberculosis to antituberculous drugs was studied using the proportion method; 773 strains were from HIV-negative patients and 52 from HIV-positive patients.

RESULTS

Thirty-four out of the 824 strains were resistant to one or more drugs: 31 (4%) from HIV-negative patients and 3 (5.7%) from HIV-positive patients. The resistance to the different drugs for strains from HIV-negative patients was: streptomycin, 2.4%; isoniazid, 1.8%; ethambutol, 0.6%, and rifampin, 0.2%. For HIV-positive patients, resistance to streptomycin was 5.7% and to isoniazid 1.9%. Resistance to a single agent was the resistance mode observed most commonly: 23 (2.9%) in HIV-negative patients and 2 (3.3%) in HIV-positive patients. There was not a single strain resistant to isoniazid and rifampin.

CONCLUSIONS

The incidence of PR in the surveyed area was low, including isoniazid. The group of HIV-positive patients did not show a significant increase in resistance (p = 0.4; OR, 1.44; 95% CI, 0.43-4.86). Regular surveillance of drug resistance is recommended to adjust therapeutic regimes.