Investigation of Healthcare-associated Transmission of Mycobacterium Tuberculosis Among Patients with Malignancies at Three Hospitals and at a Residential Facility

Background: Immunocompromised patients have an increased risk of experiencing progression of latent Mycobacterium tuberculosis infection (LTBI) to active tuberculosis (TB) disease. In January 2002, 2 patients with leukemia (Patients 1 and 2) developed pulmonary TB after recent exposure at 3 hospitals (Hospital A, Hospital B, and Hospital C) and at a residential facility for patients with cancer. Neither was known to have LTBI. Within 1 year, 3 other patients with malignancy and TB disease had been identified at these facilities, prompting an investigation of healthcare facility-associated transmission of M. tuberculosis.

Methods: The authors performed genotypic analysis of the five available M. tuberculosis isolates from patients with malignancies at these facilities, reviewed medical records, interviewed individuals who had identical M. tuberculosis genotypic patterns, and performed tuberculin skin testing (TST) and case finding for possible exposed contacts.

Results: Only Patients 1 and 2 had identical genotypic patterns. Neither patient had baseline TST results available. Patient 1 had clinical evidence of infectiousness 3 months before the diagnosis of TB was ascertained. Among employee contacts of Patient 1, TST conversions occurred in 1 of 59 (2%), 2 of 34 (6%), 2 of 32 (6%), and 0 of 8 who were tested at Hospitals A, B, and C and at the residential facility, respectively. Among the others who were exposed to Patient 1, 1 of 31 (3%), 1 of 30 (3%), 0 of 40 (0%), and 12 of 136 (9%) who were tested had positive TSTs at Hospitals A, B, and C and at the residential facility, respectively.

Conclusions: Delayed TB diagnosis in 2 patients with leukemia resulted in the transmission of M. tuberculosis to 19 patients and staff at 3 hospitals and a residential facility. Baseline TB screening and earlier clinical recognition of active disease could reduce healthcare facility-associated transmission of M. tuberculosis among patients with malignancy.