[Outbreak of extensively drug-resistant pulmonary tuberculosis in a hemodialysis facility]

We experienced an outbreak of extensively drug-resistant pulmonary tuberculosis (XDR-TB) in a hemodialysis facility. The primary case involved a 51-year-old male hemodialysis patient, with a history of treatment for Mycobacterium tuberculosis infection seven years previously. There was no drug resistance, and the patient completely recovered after undergoing treatment with isoniazid (INH), rifampicin (RFP) and ethambutol (EB). He was admitted to another hospital due to a recurrence of pulmonary tuberculosis in June 2006. At first, he was treated with HRS [INH, RFP and streptomycin (SM)]; however, the drug regimen was changed to INH, EB, levofloxacin (LVFX) and kanamycin (KM) in August following the results of a drug susceptibility test. Although the patient was receiving outpatient tuberculous therapy, he was readmitted in June 2007 due to relapse and conversion of a sputum culture to positive status. Additionally, the XDR-TB organism was identified. Following these events, five staff members of the hemodialysis facility and a member of the patient's family were diagnosed with XDR-TB infection. The staffs who were infected with XDR-TB had worked in the same dialysis room, drug resistance was found in all cases and drug resistant gene mutations were found in three cases; therefore, we considered this to be an outbreak. As XDR-TB infection was suspected in all cases, no patients took drugs to treat latent tuberculosis infection (LTBI). Regarding the causes of the outbreak, the first is the delay of four months in making a diagnosis of re-exacerbation of tuberculosis. Second, in Case 2, the patient developed laryngeal and tracheobronchial tuberculosis after first being diagnosed with asthma, and the tuberculosis diagnosis was delayed. Third, the sputum smear of Case 2 was strongly positive. There is only one previously reported outbreak of XDR-TB in Japan; therefore, we consider this outbreak to be educational.