Transmission of multidrug-resistant tuberculosis in the UK: a cross-sectional molecular and epidemiological study of clustering and contact tracing.

Background: Between 2000 and 2012 the number of multidrug-resistant (MDR) tuberculosis cases in the UK increased from 28 per year to 81 per year. We investigated the proportion of MDR tuberculosis cases arising from transmission in the UK and associated risk factors.

Method: We identified patients with MDR tuberculosis notified in England, Wales, and Northern Ireland between Jan 1, 2004, and Dec 31, 2007, by linking national laboratory and surveillance data.