First outbreak of multidrug-resistant tuberculosis (MDR-TB) in Denmark involving six Danish-born cases

• Published in: International journal of infectious diseases 2022-04, Vol.117, p.258-263
• Main Authors: Suppli, Camilla Hiul, Norman, Anders, Folkvardsen, Dorte Bek, Gissel, Tina Nørregaard, Weinreich, Ulla Møller, Koch, Anders, Wejse, Christian, Lillebaek, Troels
• Format: Article
• Language: English
• Subjects: Antitubercular Agents - therapeutic use; contact tracing; Denmark; Denmark - epidemiology; Disease Outbreaks; Humans; MDR-TB; Mycobacterium tuberculosis - genetics; Tuberculosis; Tuberculosis, Multidrug-Resistant - drug therapy; Tuberculosis, Multidrug-Resistant - epidemiology; Tuberculosis, Multidrug-Resistant - microbiology; whole genome sequence WGS
• ISSN: 1201-9712; 1878-3511
• DOI: 10.1016/j.ijid.2022.02.017

•Elucidating the first Danish MDR-TB outbreak spanning 10 years.•Combining classic and molecular epidemiology with clinical information.•Molecular genotyping data reveals an unknown MDR-TB outbreak source.•MDR-TB can occur in a resource-rich TB low incidence setting. Denmark is a low-incidence country for tuberculosis (TB) and multidrug-resistant (MDR) TB at 5 and 0.05 cases per 100,000 population, respectively. Until 2018, the transmission of MDR-TB was nonexistent except for a few pairwise related family cases. In this study, we describe the first MDR-TB outbreak in Denmark. On the basis of genotyping of all Mycobacterium tuberculosis (Mtb) culture-positive cases in Denmark spanning 3 decades, 6 molecular- and epidemiologically linked Danish-born cases were identified as the first cluster of an MDR-TB in Denmark. The primary case was diagnosed posthumously in 2010 followed by 5 epidemiologically linked cases from 2018 to 2019. Through a combination of routine Mtb genotyping and clinical epidemiological surveillance data, we identified the first Danish MDR-TB outbreak spanning 10 years and were able to disclose the specific transmission pathways in detail, which helped guide the outbreak investigations. The occurrence of an MDR-TB outbreak in a resource-rich low TB incidence setting such as Denmark highlights the importance of a collaborative control system combining classic contact tracing; timely identification of drug-resistant TB through rapid diagnostics; and a close collaboration between clinicians and classical- and molecular epidemiologists for the benefit of TB control.