Donor Derived Pulmonary Tuberculosis (TB) in Lung Transplant Recipients: Lessons Learned from Investigation of Two Cases of TB following Lung Transplantation

Background:

Prevention of TB in solid organ transplant recipients (SOTRs) and transplant centers (TCs) is of paramount importance.  Between August 2008 and July 2009, 2 (5%) of 42 patients undergoing lung transplantation developed pulmonary TB within three months of transplant at a single TC where TB had not identified in over 2500 preceding SOTRs. 

Objective:

To identify sources and causes of TB in two lung transplant recipients by epidemiologic investigation and Mycobacterium tuberculosis (Mtb) strain genotyping.

Methods:

Donor and recipient medical records and reports to the United Network for Organ Sharing were reviewed.  Household and family contacts of the recipients were interviewed.  Contacts of the recipients at the TC were assessed for evidence of recent or active Mtb infection.  Genotyping of the Mtb isolates was completed and compared to state and national archives.  

Results:

Prior to transplant, the two case patient (CP) recipients were without evidence of Mtb infection by clinical evaluation and tuberculin skin testing (TST).  TB was identified, in the absence of new complaints, by culture of respiratory specimens recovered at protocol bronchoscopic evaluations 50 and 94 days following double lung transplantation of CP1 and CP2, respectively.  As of 12 months and 10 months following transplantation of CP1 and CP2, respectively, 1 of 9 other recipients of organs from the 2 donors had died without evidence of TB and 8 were alive without evidence of TB (1 given anti-TB chemoprophylaxis).  Review of donor medical records did not identify evidence of active TB; no record of TST was recovered for either.  Donor for CP2 however expired within months of returning from a year’s residence in the Phillipines.  No evidence of new or active TB in healthcare worker contacts of CP1 and CP2 at the transplant center was identified.  Genotyping of the Mtb isolate recovered from CP1 identified a strain very similar to an epidemic strain with which a possible epidemiologic link was established for CP1’s donor.  Genotyping of the isolate recovered from CP2 identified a strain that was not related to other strains recovered at the transplant center or to other known outbreak strains.

Conclusions:

Unrecognized donor Mtb infection appears to have been responsible for one and possibly two cases of post-lung transplant pulmonary TB at a single TC.  Surveillance Mtb culture of bronchoscopic specimens obtained early after lung transplantation can identify Mtb infection in the absence of associated disease.  Genotyping of Mtb isolates can critically assist identification of sources of infection.  Investigation of interferon gamma release assay testing of lung transplant donors to prevent TB in transplant recipients and Mtb transmission in transplant centers is warranted.