MOLECULAR APPROACH TO IDENTIFYING ROUTE OF TRANSMISSION OF TUBERCULOSIS IN THE COMMUNITY

There is growing concern that tuberculosis is spread in Europe in the way that it is in the USA. We have used DNA ''fingerprinting'' in a sy stematic evaluation of tuberculosis cases notified in our community to uncover foci of transmission. An IS6110 probe was used to test all is olates from culture-confirmed tuberculosis cases (163 patients) notifi ed in 1991-92 in the Canton of Berne. In total, 45 patients (27.6%), p otentially linked on the basis of restriction fragment length polymorp hism, were investigated edepidemiologically. The largest group (n = 22 ) included members of a defined social group (drug addicts, homeless p ersons, alcoholics), from whom tuberculosis spread to the general popu lation. A key patient developed multidrug-resistant tuberculosis durin g the surveillance period. This population study showed that (i) exten sive transmission of Mycobacterium tuberculosis is now taking place in Europe in the same social setting as in the USA; (ii) there is defini te ''spillover'' to the general population; (iii) the dimensions of th e problem cannot be recognised easily by routine public health service activities because of the complexity of the transmission network; and (iv) multidrug-resistant tuberculosis develops in this setting.