[AN OUTBREAK OF PULMONARY TUBERCULOSIS DUE TO DEFINITE EXOGENOUS REINFECTION AMONG ELDERLY INDIVIDUALS IN WELFARE FACILITIES].

Purpose: We report an outbreak of 64 cases of tuberculosis (TB) that spread in a welfare facility for elderly individuals.

Objective and methods: First, 64 TB patients who had contact with the source patient were screened at our hospital. We examined the time course up to the discovery of symptoms and analyzed the results for variable numbers of tandem repeats (VNTR) and the drug susceptibility tests. Second, we performed chest computed tomography to examine lesions due to a previous TB infection.

Result: The source patient had recurrent aspiration pneumonia. The delay in doctor consultation was considered day 0, and the delay of diagnosis was 267 days. On examining the contacts, we found that 29 patients had TB while 35 had a latent TB infection. Results of the VNTR and the drug susceptibility tests showed that all the patients who developed TB had the same pattern as that of the source patient. Chest computed tomography showed lesions due to a previous TB infection in 8 patients.

Conclusion: Based on the results of the VNTR and drug susceptibility tests, we concluded that the outbreak was due to an exogenous infection from the same source. All 8 patients who showed lesions due to a previous TB infection were aged > 81 years, and TB in these patients was found to be due to exogenous re-infection.