Transmission of multidrug-resistant tuberculosis

Aim. To compare the Mycobacterium tuberculosis isolates of adult index case s with multidrug-resistant (MDR) tuberculosis to the isolates obtained from their child contacts. Patients and methods, A 4-year prospective study in the Western Cape Provin ce of South Africa. We evaluated 149 child contacts of 80 adult MDR pulmona ry tuberculosis cases. This report includes those cases where a culture for M, tuberculosis was obtained from both the adult source case and the child contact, Isolates were compared by drug susceptibility pattern and restric tion fragment length polymorphism analysis. Results. Six adult-child pairs with cultures for M, tuberculosis were ident ified. Two children had contact with more than one adult tuberculosis case, One child received previous isoniazid prophylaxis. Drug susceptibility pat tern and re striction fragment length polymorphism analysis were identical for five adult-child pairs. One child, with no other known source case, had a strain different from that of the identified source case, but the MDR M, tuberculosis strain with which he was infected was prevalent in the commun ity in which he resided, Al children responded well to treatment. Conclusion, This study confirms that most of the childhood contacts of adul ts with MDR tuberculosis are likely to be infected by these MDR source case s despite their exposure to other drug-susceptible adults with tuberculosis in some instances. Child contacts of adults with MDR tuberculosis should b e treated according to the drug susceptibility patterns of the likely sourc e cases' M. tuberculosis strains unless their own strain's susceptibility t esting indicates otherwise. Contact tracing remains of fundamental importan ce in identifying children at risk.