Objectives: To determine the prevalence of M. tuberculosis isolates resistant to drugs in a general hospital and to assess its association with HIV infection.
Materials and methods: Susceptibility analysis of all isolates of M. tuberculosis in a 4-year period (1990-1993). The proportion method was used to study the susceptibility to eight drugs. To assess the association of resistance with HIV infection a crossing was made of patients records who had M. tuberculosis recovered and that of patients with positive serology to HIV.
Results: Forty-two out of a total of 760 isolates (5.5%) were resistant to at least one drug, including isoniazid in 27 (3.3%), rifampin in 13 (1.6%), and pyrazinamide in 2 (0.2%). None of the isolates was resistant to ofloxacin. Twenty isolates (2.6%) were resistant to more than one drug and 9 (1.2%) were resistant to at least isoniazid and rifampin. Overall, 39% of resistance to one drug occurred in patients who had not received previous therapy with that drug. A greater incidence of resistant isolates was observed in HIV+ patients (7.3%) than in HIV- patients (4.6%), although this difference did not reach a statistical significance.
Conclusions: Drug resistance rate in M. tuberculosis isolates in our hospital is still low and apparently not associated with HIV infection.