Anti-tuberculosis drug resistance in Portugal

A survey based upon a representative sample of smear-positive pulmonary tuberculosis patients was undertaken in Portugal, as part of the World Health Organization's Global Project on Anti-Tuberculosis Drug Resistance Surveillance.

To determine the level of primary antituberculosis drug resistance at both national and regional levels, and to assess its relative weight within the performance of the National Tuberculosis Programme (NTP).

Mycobacterium tuberculosis isolates from 1,105 patients with smear-positive pulmonary tuberculosis admitted to 46 randomly stratified treatment centres all over mainland Portugal were submitted to susceptibility testing with four drugs. Human immunodeficiency virus (HIV) testing was included in the patients' evaluation scheme.

Of the strains isolated, 197 (17.8%) were resistant to at least one drug. Primary resistance to isoniazid was 7.7% and to rifampicin 1.9%. Acquired drug resistance was 39.2% in total, any acquired resistance to isoniazid 31.1% and to rifampicin 20.9%. Primary multidrug resistance (MDR) was 1.8% and acquired MDR was 20.9%. HIV testing was positive in 29.2% of MDR-TB cases.

Drug resistance in Portugal is high. Primary MDR and particularly acquired MDR occur in a high proportion of cases, indicating a need for improvement in NTP performance.