Background: A network for the Surveillance of Antituberculosis Drug Resistance (VigLab-Tuberculose), including all the mycobacterial laboratories where drug susceptibility test on isolates of Mycobacterium tuberculosis complex are carried out, was established in Portugal in April 2000. VigLab-Tuberculose aims to maintain a laboratory-based surveillance system for antibiotic susceptibilities of Mycobacterium tuberculosis complex isolates in order to monitor trends in drug resistance in Portugal.
Objective: To describe the first line antituberculosis drug resistance patterns of tuberculosis cases diagnosed and reported to VigLab-Tuberculose in 2000-2001.
Methods: Collaborating laboratories collect and report data on individuals from whom a drug susceptibility test on Mycobacterium tuberculosis complex isolates has been performed in 2000-2001. Data collected included demographic, geographic, clinical and first line antibiotics susceptibility information. Data were analysed using Epi-Info version 6.04c software.
Results: There were 4170 reports of drug susceptibility test results on tuberculosis patients diagnosed from 1st April 2000 to 31st December 2001. Drug susceptibility results for all five first line antituberculosis drugs shows that 23% (541/2358) were resistant at least to one of them. The proportion of mono-resistance to streptomycin was 7,6% (179/2358), to isoniazid 2,6% (62/2358), to rifampicin 0,6% (15/2358) and to pyrazinamide 1,3% (30/2358). From the 4164 patients tested both to isoniazid and rifampicina, 244 (5,9%) were multidrug resistant. From patients with no history of previous tuberculosis treatment, 1,8% (28/1557) were mono-resistant to isoniazid, 0,4% (7/1557) to rifampicina, 4,2% (66/1557) to streptomycin and 1,7% (27/1557) to pyrazinamide. The proportion of primary multidrug resistance was 2,8% (43/1557) and acquired resistance was 13,3% (41/309).
Conclusion: The laboratory participation rate was 80%, which is very encouraging for the first two years of VigLab-Tuberculose activities. The proportion of primary multidrug resistance was higher than the reported resistance from central and west Europe (less 1%), which reinforce the need and importance of maintaining and strengthening the laboratory-based surveillance in order to minimise the emergence of drug resistance.