Outbreak of multiple drug-resistant tuberculosis in Lisbon: Detection by restriction fragment length polymorphism analysis

Isabel Portugal, M. J. Covas, L. Brum, M. Viveiros, P. Ferrinho, J. Moniz-Pereira, H. David

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SETTING: Multidrug-resistant tuberculosis (MDR-TB) mainly among human immunodeficiency virus (HIV) seropositive patients in Lisbon hospitals in 1996-1997. OBJECTIVE: Detection of transmission of MDR-TB strains and epidemic outbreaks in several hospital units in the city of Lisbon, including a prison hospital. DESIGN: Use of restriction fragment length polymorphism (RFLP) to fingerprint isolates of Mycobacterium tuberculosis resistant to isoniazid, rifampicin, and one other drug. RESULTS: A total of 43 MDR-TB strains were typed. Sixty-seven per cent of the patients were HIV positive, 12% were HIV negative, and the remainder had unknown HIV status. About 88% of the isolates were grouped in three genetically similar dusters, suggesting possible recent transmission. A predominant cluster (cluster A), corresponding to 72% of the cases, was found, 45% of which carne from the prison hospital. Strains from this cluster were resistant to isoniazid, rifampicin, streptomycin, and sometimes ethambutol. A retrospective epidemiological investigation was conducted with respect to all patients in cluster A, and epidemiological links were established between them. CONCLUSION: Our results suggest recent transmission of MDR-TB, mainly in HIV- positive patients, in Lisbon hospitals. Moreover, the predominant MDR-TB clustered strains were not confined tO HIV-infected individuals, as they were also isolated in some immunocompetent patients.

Original languageEnglish
Pages (from-to)207-213
Number of pages7
JournalInternational Journal of Tuberculosis and Lung Disease
Issue number3
Publication statusPublished - Mar 1999


  • Lisbon
  • Multi-drug resistance (MDR)
  • Outbreak
  • RFLP
  • Tuberculosis


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