RT Journal Article SR Electronic T1 Extensively drug-resistant tuberculosis in South Africa: genomic evidence supporting transmission in communities JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP 1800246 DO 10.1183/13993003.00246-2018 VO 52 IS 4 A1 Sara C. Auld A1 N. Sarita Shah A1 Barun Mathema A1 Tyler S. Brown A1 Nazir Ismail A1 Shaheed Vally Omar A1 James C.M. Brust A1 Kristin N. Nelson A1 Salim Allana A1 Angela Campbell A1 Koleka Mlisana A1 Pravi Moodley A1 Neel R. Gandhi YR 2018 UL http://erj.ersjournals.com/content/52/4/1800246.abstract AB Despite evidence that transmission is driving an extensively drug-resistant TB (XDR-TB) epidemic, our understanding of where and between whom transmission occurs is limited. We sought to determine whether there was genomic evidence of transmission between individuals without an epidemiologic connection.We conducted a prospective study of XDR-TB patients in KwaZulu-Natal, South Africa, during the 2011–2014 period. We collected sociodemographic and clinical data, and identified epidemiologic links based on person-to-person or hospital-based connections. We performed whole-genome sequencing (WGS) on the Mycobacterium tuberculosis isolates and determined pairwise single nucleotide polymorphism (SNP) differences.Among 404 participants, 123 (30%) had person-to-person or hospital-based links, leaving 281 (70%) epidemiologically unlinked. The median SNP difference between participants with person-to-person and hospital-based links was 10 (interquartile range (IQR) 8–24) and 16 (IQR 10–23), respectively. The median SNP difference between unlinked participants and their closest genomic link was 5 (IQR 3–9) and half of unlinked participants were within 7 SNPs of at least five participants.The majority of epidemiologically-unlinked XDR-TB patients had low pairwise SNP differences with at least one other participant, consistent with transmission. These data suggest that much of transmission may result from casual contact in community settings between individuals not known to one another.Much of XDR-TB transmission may arise from casual contact between individuals not known to one another http://ow.ly/4Wqt30lnHtp