[Resistant tuberculosis is spreading in Sweden. Molecular epidemiological strain identification by "fingerprinting" can make the infection tracing easier].

Resistance of Mycobacterium tuberculosis to antibiotics is a world wide problem. A study is reported with the aim to analyse the spread of resistant isolates of M tuberculosis complex from patients with tuberculosis in Sweden. The study is based on a sample of 192 M tuberculosis complex isolates from patients with drug resistant tuberculosis during 1994-2000. All isolates resistant to at least one of the drugs streptomycin, isoniazid, ethambutol and rifampicin were included in the study. Restriction fragment length polymorphism (RFLP) was performed, using IS6110 as a probe for hybridisation. Visualised bands were analysed by Gel Compar software. The majority of the isolates were from patients born in high TB prevalence countries. During the years 1996-2000 there was one major cluster generated from 34 isolates. In 1996-1998 there were two isolates per year, in 1999 it increased to 20 isolates, and eight cases in 2000. All strains were resistant to isoniazid. All patients in this cluster were found to be from Africa. In comparing the pattern in the T-base the strains matched with strain BEA-000007341 isolated from a patient in Rwanda. The majority of patients with drug resistant tuberculosis in Sweden are immigrants from countries with high incidence of tuberculosis. Spread of disease to the Swedish born population is uncommon. However, an increasingly prevalent clone of isoniazid resistant tuberculosis was found among African immigrants, mainly living in the Stockholm area.