Retrospective Analysis of Multi-Drug Resistant Tuberculosis (Mdr-Tb) Diagnosis among Contacts in East London: Insights and Implications

Abstract

Introduction Despite a decline in the incidence of multi-drug resistant tuberculosis (MDR-TB) in the last decade, East London continues to experience a significant burden of disease. MDR-TB poses concern for clinicians due to its poorer clinical outcomes and public health implications. Current guidelines do not differentiate between contact tracing for MDR-TB and fully sensitive TB, nor do they recommend preventative treatment for MDR-TB contacts. Methods We conducted a retrospective cohort study of all consecutive MDR-TB cases treated by our service in the past five years, using data from the National TB Registry and local electronic records. Results Between January 2019 and June 2024, our service treated 33 MDR-TB cases. Of these, six (18.1%) were contacts of an index case, distributed across three separate clusters. All contact cases were linked to smear-positive household index cases. Screening followed NICE guidelines, including symptom assessment, chest radiograph (CXR), and interferon gamma release assay (IGRA). One contact was symptomatic at screening, with a sputum culture confirming MDR-TB. Of the remaining five, four were IGRA positive at screening and one was IGRA negative. All five had normal CXRs at screening, and two of these also had a normal CT chest at the time. Four of the five contacts later developed symptoms with subsequent diagnosis of MDRTB, while one remained asymptomatic but had an abnormal interval CXR with subsequent CT chest and bronchoscopy leading to MDR-TB diagnosis. None of the contacts were smear-positive. The median time to contact diagnosis following MDR-TB confirmation in the index case was 25 weeks (IQR 11 weeks). Conclusion Our findings suggest current screening guidelines for MDR-TB contacts may be inadequate. Contacts of smearpositive MDR-TB index cases might benefit from closer radiological follow-up, with serial CXRs in the first six to twelve months or a baseline CT chest at screening. While the use of preventative levofloxacin in MDR-TB contacts has shown effectiveness in high incidence settings, randomised controlled trials evaluating preventative treatment of MDR-TB contacts in low incidence settings are urgently needed.