Abstract:

Objective To analyze the epidemiological characteristics and control measures of a clustered outbreak of multidrug-resistant pulmonary tuberculosis in a school campus in Changsha City for reference in following management of such accident. Methods The information, including the school campus settings, the primary case of tuberculosis and clinical diagnosis, was collected, and then we conducted screening on the close and general contacts for suspicious symptoms of pulmonary tuberculosis by tuberculin skin test (TST) and chest X-ray examination according the procedures specified in the Guidelines for Prevention and Control of Tuberculosis in Schools in China (2020). Drug sensitivity testing was performed for the primary case, and for the pulmonary tuberculosis cases found in screening, multilocus sequence typing (MLST) analysis of Mycobacterium tuberculosis was further carried out to construct phylogenetic tree to determine epidemiological association between cases and effective treatment of the epidemic. Results After identification of the index case, 46 close contacts underwent first round of tuberculosis screening, which revealed that 5 subjects were moderate positive or above for TST, and 2 new active cases were found. No new cases were found after expanded screening of 51 general contacts living in the dormitory at the same floor as the index patient. Four cases were moderate positive or above for TST. Subsequent screening of the close and general contacts revealed 9 cases being moderate positive or above for TST. According to the drug sensitivity test results, all three cases were multidrug-resistant tuberculosis, and the MLST analysis results were used to draw an evolutionary tree. The analysis suggested that there was correlation among the 3 cases involved in this epidemic, and the index case was highly likely to be the patient zero. However, analysis results of the strain sequencing data before and after treatment of the same case showed heterogeneity. Conclusion This clustered outbreak is a multi-drug resistant tuberculosis cluster epidemic. MLST or combined it with drug sensitivity and epidemiological investigation results may provide reference and evidence for inferring the correlation between cases.

Key words: Multidrug-resistant pulmonary tuberculosis, School, Clustered epidemic, Changsha City