[Evolution of drug-resistant Mycobacterium tuberculosis in the province of Castellón. 1992-1998]

To determine the frequency of resistant Mycobacterium tuberculosis and the risk factors associated with resistance in the province of Castellón (Spain).

This prospective study of M. tuberculosis sensitivity applied Canetti's method of proportions to all strains isolated in Castellón (n = 532) from January 1992 through December 1998 (7 years); 461 cases were new.

The overall frequency of resistant strains was 4.7% (25/532), of which 3.9% (18/461) were instances of primary resistance and 11.1% (7/63) were of secondary resistance. Three percent were resistant to isoniazid, 1.87% to rifampicin, 1.87% to streptomycin and 0.56% to ethambutol. Multiple drug resistance was found in 0.2% (1/461) of the new cases and 1.1% (6/532) overall. The presence of resistant M. tuberculosis was associated with a history of antituberculous treatment (OR = 3.14; p = 0.017) and the presence of one or more risk factors for tuberculosis (OR = 3.32; p = 0.066).

The overall rates of resistant M. tuberculosis and multiple drug resistance are low in the province of Castellón; however resistance is associated with higher mortality such that controlling some preventable risk factors might reduce the frequency of resistance.