Multidrug resistant tuberculosis (MDR-TB) incidence in close contacts of pulmonary MDR-TB index cases in East London - a retrospective study

<bold>Introduction:</bold> Although the incidence of multidrug resistant tuberculosis (MDR- TB) in the UK has decreased over the past few years, the rates of MDR-TB in East London remain high. There are no existing guidelines for treating close contacts of newly diagnosed MDR-TB cases in low TB incidence countries. This study aims to analyze the rates of MDR-TB among close contacts of TB index cases with pulmonary MDR-TB in East London, the area with one of the highest rates of TB in the UK. <bold>Methods:</bold> This is a retrospective cohort study using data from the National Tuberculosis Registry of all consecutive TB cases with pulmonary MDR-TB diagnosed between 2013 and 2023 diagnosed at our institution in East London and their close contacts (those sharing a household or having prolonged close contact with the index case). <bold>Results:</bold> There were twenty index cases of MDR-TB registered from 2013 to 2023, sixteen were male, the median age was 40 years (IQR 8.25). The ethnic origin was 50% White, 20% Black, 25% South Asian and 5% Other. We identified 86 close contacts in these 20 index cases, 61 adults and 25 children, an average of 4.3 per index case. 62 contacts were assessed radiologically, clinically and with an interferon gamma assay (IGRA). A total of 15 (24.2% of those screened) contacts had latent TB infection. Five contacts (8.1%), all adults, were positive for active MDR-TB after screening and received treatment. <bold>Conclusion:</bold> Recent evidence in high TB incidence countries has shown that Levofloxacin reduced the risk of developing MDR-TB in contacts. We need urgent prospective studies in low incidence countries to guide on preventive treatment of contacts of MDR-TB.